WHAT IS DIABETES? | Added: 12, August 2017

What is a general definition of diabetes?

Diabetes is considered a complex group of diseases with a variety of causes. It is also often called a syndrome, or a combination of associated conditions. In most cases, people with diabetes have a high amount of glucose (a sugar) in their blood, also referred to as high blood glucose (or sugar) levels or, in the case of extremely high glucose levels, hyperglycemia. It is a disease that occurs when for various reasons the body’s cells are unable to absorb excess glucose from the blood, which causes an overabundance of the sugar in the body. This is a very basic definition, as there are several types of diabetes, including type 1, type 2, and gestational diabetes.

For simplicity, and because most media mentions that diabetes is a disease (after all, it does include a collection of diseases with various causes), the remainder of this text will mention diabetes as a “disease” not a “syndrome.”

What is the medical term for the condition caused by the body’s inability to produce or use insulin?

Diabetes mellitus is the medical term for the disease associated with the body’s inability to naturally produce or use insulin. There are two major types-one is considered an autoimmune disease (type 1), and the other is a disorder of the body’s metabolism, or the way the body processes food for energy (type 2). In general, diabetes occurs when the pancreas either produces little or no insulin, or when the cells do not respond appropriately to the insulin that is produced. Because of either of these conditions, glucose (sugar) builds up in the bloodstream (causing high blood glucose levels) and overflows into the urine. This excess amount of glucose is why a health care professional will tell patients newly diagnosed with diabetes that they have “high blood glucose levels.”

What is insulin?

Insulin is a hormone produced by the beta cells in the pancreas, an approximately six-inch-long organ found behind the stomach and below the liver. After a meal is eaten, insulin is released from the pancreas in response to rising blood glucose levels (most foods cause a person’s blood glucose level to rise). The insulin then helps the passage of the glucose, along with amino acids and fatty acids, into the body’s cells, which helps facilitate storage for future energy needs and cellular growth. (For more about insulin and the pancreas, see the chapter “How Diabetes Affects the Endocrine System”; for more details about insulin, see the chapter “Taking Charge of Diabetes.”)

What is insulin resistance?

Insulin resistance is a condition most associated with type 2 diabetes. It occurs when the body’s natural hormone insulin is less effective in reducing a person’s blood glucose levels. This is caused by the body’s cells being resistant to insulin’s action, and/or not enough insulin is made in the pancreas. Either situation makes the glucose levels rise and, if severe enough, can lead to type 2 diabetes and other health problems. (For more about insulin resistance, see the chapter “Prediabetes and Type 2 Diabetes.”)

Insulin is the hormone that allows cells in our bodies to absorb sugar.

What is glucose?

During digestion, the fats, carbohydrates, and proteins consumed are eventually broken down into smaller components that can be used by the body’s cells. One of the components is glucose, a six-carbon sugar that is a fuel providing energy the body’s cells need. It is the imbalance of this glucose in the body-mainly too much glucose-that can lead to diabetes. (For more about glucose and the digestive tract, see the chapter “How Diabetes Affects the Digestive System.”)

What is the difference between “sugar” and “glucose” in discussing diabetes?

The terms “sugar” and “glucose” are often used interchangeably in relation to diabetes. Both terms are actually correct, as glucose is a form of sugar. But the term “sugar” is more commonly used by the public, which is why many people will say they “have sugar” when they are diagnosed with any type of diabetes.

What is glucagon?

Glucagon is a hormone produced by the pancreas’s alpha cells. This hormone is responsible for increasing the concentration of glucose in the blood. It is secreted from the pancreas when the blood glucose levels fall below normal. Glucagon actually stimulates the liver to convert glycogen to glucose, which causes the person’s blood glucose level to rise. It does this by stimulating the production of glucose from amino acids and lactic acid in the liver and stimulates the release of fatty acids from fat (also called adipose) tissues. And when blood glucose levels sufficiently rise in the blood, the secretion of glucagon decreases as part of what is called a negative feedback system. (For more about glucagon and the pancreas, see the chapter “How Diabetes Affects the Endocrine System.”) Glucagon can also be made synthetically and often comes in what is called a “glucagon kit,” which is often used when a person with diabetes experiences a severe hypoglycemic episode, which is when blood sugar gets too low. (For more about glucagon kits, see the chapter “Taking Charge of Diabetes.”)

What does “plasma-glucose level” mean?

Plasma-glucose level is what is referred to by most people-and throughout this book-as blood glucose level. The term plasma refers to the liquid part of the blood that remains after the blood cells have been removed. This is the part of the blood, too, that is analyzed when a person has his or her blood glucose levels checked in a laboratory or doctor’s office. All blood glucose meters are calibrated to measure the plasma-glucose level within a blood sample, although most people still say “blood glucose level.”

Is blood the only part of the body that contains glucose?

No, there are many “liquids” associated with the human body that contain glucose, not just the blood. For example, saliva, sweat, and tears contain glucose, as was known as far back as the 1930s. And of course, all the body’s cells contain glucose because they need that component for energy.

What are the most common types of diabetes?

Diabetes is commonly divided into several categories, depending on the severity, initial occurrence of the disease, and the cause of the diabetes. The most common types are prediabetes, type 1 and type 2, and gestational diabetes. (For more details about prediabetes, types 1 and 2 diabetes, gestational, and the many other forms of diabetes, see their respective chapters.) The following lists the general conditions for these forms of diabetes:

Prediabetes (also called impaired glucose tolerance [IGT] or impaired fasting glucose [IFG], depending on the test used): When a person has blood glucose (sugar) levels above the normal range but not high enough to be diagnosable as diabetes, he or she is considered prediabetic.

Type 1 (also seen as type I, type 1, or T1D): Also referred to as immune-mediated diabetes mellitus-formerly called insulin-dependent diabetes mellitus or juvenile diabetes. People with type 1 diabetes do not make enough insulin, the protein hormone made by the pancreas that helps the body use (and store) glucose from food.

Does eating sugar cause type 1 or type 2 diabetes?

No, eating sugar does not cause type 1 or type 2 diabetes. Neither does eating fruit or vegetables that contain various types of sugars. In fact, if a person has a healthy pancreas, eating a modest amount of sugar in its various forms can help that organ produce more insulin for the body to use.

That being said, it is thought that there are several reasons that a person develops type 2 diabetes, and many are connected to sugar. Indirectly, the disease can often be “helped along” by the ingestion of the various types of sugar. For example, if the person’s pancreas is diseased or does not function well, it can cause the body to process sugars incorrectly, which can lead to diabetes. If a person eats too many sweets, the pancreas can eventually have a difficult time handling the excess sugar, and a person can develop type 2 diabetes. If a person has a genetic predisposition to type 2 diabetes and/or overeats (often by eating too many sweets), becoming obese, this can lead to diabetes. Thus, sugar has been known to affect a person and can help lead to diabetes, but it is not the cause of the disease. (For more about sugar and diabetes, see the chapter “Diabetes and Eating.”)

Type 2 (also seen as type II, type 2, or T2D): Also called insulin-resistant diabetes mellitus or adult-onset diabetes by some (although many do not use these terms anymore), type 2 diabetes usually occurs for two reasons. A person can develop type 2 diabetes when the body becomes less responsive to insulin, also known as insulin resistance. Or it can occur when the pancreas supplies too little insulin to keep up with the increased demand when a person has insulin resistance.

Gestational diabetes: Also called gestational diabetes mellitus, it occurs during some pregnancies, but not all. It is a form of diabetes that affects between 5 and 9 percent of pregnant women (depending on the study) in the United States. There are usually no symptoms or the symptoms are mild, and it is usually found during a fasting blood glucose test.

Why are there so many misconceptions when it comes to understanding diabetes?

One of the main reasons for misconceptions concerning diabetes is that it comes in several different but related forms. Someone who has type 1 diabetes develops the disease differently from a person with type 2 diabetes. But because many of the symptoms of the disease are similar and often overlap, many people confuse the true causes behind the two types.

Many other misconceptions about diabetes originated from how the disease was treated over the past century. For example, even the common phrase “I have sugar”-usually meant to indicate that a person has diabetes-is why most people think eating too much sugar will cause the disease, but this is definitely a myth (see sidebar).

If a person is overweight or obese, will he or she always develop type 2 diabetes?

No, not everyone who is overweight or obese will develop type 2 diabetes. In fact, some people who are normal weight or even moderately overweight can develop the disease. But having such extra weight often means the person has a higher risk for the disease. There also are other factors, such as family history (genetics), age (older people are more at risk to develop the disease), and ethnicity, that can also mean a higher risk of developing type 2 diabetes. (For more about diabetes and obesity, see the chapter “Diabetes and Obesity.”)

Eating sugar doesn’t cause diabetes, but there are indirect links between sugar and the disease, such as how it affects the health of the pancreas.

In general, what is the difference between the causes of type 1 (or type I) and type 2 (or type II) diabetes?

Type 1, once (and still often) called insulin-dependent diabetes mellitus (IDDM), and type 2, once (and still often) called non-insulin-dependent diabetes mellitus (NIDDM), are the two most well-known types of diabetes. In general, insulin is deficient in a person with type 1 diabetes. With type 2 diabetes, a person’s insulin secretion may be normal, but the target cells for insulin are less responsive than normal, or the insulin secretion may become abnormal. (For more details about type 1, see the chapter “Type 1 Diabetes,” and for type 2 diabetes, see the chapter “Prediabetes and Type 2 Diabetes.”)

Are there divisions within divisions of type 1 and type 2 diabetes?

Yes, research has shown that both type 1 and type 2 diabetes-especially in the past decade-are truly not specific diseases but syndromes (although most health care professionals, researchers, and media still refer to diabetes as a disease). This means that within type 1 and type 2 diabetes profiles there are many subtypes and subdivisions. In fact, it is hoped that in the near future, health care professionals will be offering their patients with diabetes a wider range of therapy plans to treat-and in some cases, possibly mitigate-the effects of this syndrome. It may also mean that everyone who has diabetes will have a more personalized treatment to help cope with their specific type of diabetes.

What are some “hidden” signs of diabetes?

Not all signs of the major types of diabetes are evident. They also may mimic other health problems and are often misinterpreted. Some of the more “hidden” signs of type 1 diabetes-and to a lesser extent type 2 diabetes-include red, tender, or swollen gums and tooth decay; high blood pressure; digestive problems; excessive thirst; mental confusion and fatigue; wounds that heal slowly; and numbness, burning pain, or tingling in the hands and feet. Because some of these symptoms are also signs of other major diseases, it is important to see a health care professional to test for diabetes or other health problems if these symptoms become apparent.

What are some ways to diagnose early signs of diabetes?

Two of the best-known ways to detect early signs of any type of diabetes is to check for glucose in the urine (an “older” way of detecting glucose) and/or test for high blood glucose levels (a “newer” way of detecting glucose). Normally, the hormone insulin is produced by the pancreas, allowing the body to remove glucose from the blood and use it as fuel for cells. If a person has diabetes, the blood glucose in the body rises to unhealthy levels because the glucose is not removed at all or is not removed quickly enough.

When there is too much glucose-or when it reaches a certain level in a person’s body-the glucose essentially spills over into the urine. Although not used as much, and usually only if a test for blood glucose is not available, a special test strip exposed to a person’s urine can detect if blood sugar is high (but it cannot measure if the level is too low). The second, more reliable way (and one used by most health care professionals today) is to measure a person’s blood sugar with a blood glucose test, such as the fasting blood glucose test. (For more about blood glucose tests, see the chapter “Taking Charge of Diabetes.”)

What is the effect of diabetes on the kidneys?

There is often a connection between diabetes and kidneys for a person with diabetes. Called diabetic kidney disease, or diabetic nephropathy, it is the most common kidney disease caused by diabetes. Even when it is controlled, diabetes can lead to chronic kidney disease (CKD) and eventual kidney failure. In fact, it is estimated that more than 40 percent of people who have diabetes can expect to develop CKD. Because of this statistic, in the United States it is often said that diabetes is the most common cause of kidney failure. (For more about kidneys and diabetes, see the chapter “How Diabetes Affects the Urinary System.”)

What is the major effect of diabetes on the heart?

Diabetes and heart problems are often said to go hand in hand. After all, according to Harvard Medical School, once a person has diabetes the risk for heart disease is four to five times greater. Furthermore, it is estimated that about 65 percent of people with diabetes will die from heart disease or stroke. (For more about the heart and diabetes, see the chapter “How Diabetes Affects the Circulatory System.”)

Does diabetes run in families?

Although most people believe diabetes runs in families, whether it does or not actually depends on the type of diabetes. In general, about 80 to 90 percent of people with type 1 diabetes have no family history of the disease, while the majority of people with type 2 diabetes do have a family history of the disease.

Can aspirin affect a person with diabetes?

Yes, an aspirin can affect a person with diabetes-especially by lowering their blood glucose levels below a healthy range, but only with prolonged use and if taken in large amounts (eight or more 325-milligram [mg] tablets per day). Therefore, most doctors believe the occasional aspirin is generally safe for most people with diabetes. (But, as always, patients should check with their doctor to determine whether there is any problem with taking an aspirin and for the correct dosage of aspirin for their condition.) Most doctors usually suggest that people with diabetes check their blood glucose levels while taking the drug. Doctors should also inform patients if they need to be monitored while taking aspirin for any extended period.

Can the weather affect a person with diabetes more than a person without diabetes?

Yes, weather can affect a person with diabetes more than a person without diabetes. For example, in extreme humidity, there is always a risk of heat exhaustion. If a person with diabetes has poor glucose management-which can affect that person’s ability to sweat in the first place-he or she may have more of a tendency to overheat. And because higher blood glucose levels make people urinate more, they can also become dehydrated faster in hot, humid weather. (For more about diabetes and extreme temperatures, see the chapter “Coping with Diabetes.”)


How long has diabetes been known as a disease?

Symptoms of diabetes (though it was not called diabetes) were known around 3,500 years ago and were first recorded by the Egyptians. By the mid-seventh century, the Chinese physician Chen Ch’üan (c. 640 C.E.) also noted the symptoms of diabetes, including excessive thirst and sweet urine. In the first century, the celebrated Greek physician Aretaeus of Cappadocia (81–138 C.E.) called it diabainein, from the Greek dia (“to pass through”) and bainein (“to go”), referring to the excessive urination associated with the disease. He further noted the horrible way in which the patients with the disease met their demise, writing that, as far as he could tell, it was the “melting down of the flesh and limbs into urine.” And around the early eleventh century, the Persian physician Avicenna (980–1037) supposedly described the disease and its many consequences.

Where does the term “diabetes” come from?

The term as “diabetes” was first mentioned in 1425 (as diabete), from the Latin. This, in turn, comes from the ancient Greek words dia meaning “to pass through” and betes meaning a “water tube,” thus the loose translation that is often seen as “water siphon.” The word mellitus was added probably around 1670 (see below), from the Latin for “like honey” or “sweetened with honey” to reflect the sweet smell (and taste) of the patient’s urine.

Who was Thomas Willis?

Thomas Willis (1621–1675) was an English physician who is most remembered for his rationalist approach to the human brain and nervous system. Although many historians consider his contributions to diabetes minor (others centuries before had noted the symptoms; see above), he did rediscover that urine from people with diabetes tasted sweet and is credited with referring to the condition as diabetes mellitus, or “honey diabetes,” around 1670. (There is some disagreement as to this date, with some references suggesting that the scientific term diabetes mellitus was first used in 1860.) He is often called the “first modern Western physician” to rediscover the sweet urine–diabetes connection. But instead of sugar, he attributed the sweetness of urine to salts and acids. He also thought this disease was a rare condition before his time and believed diabetes in his time was from excessive living. He also associated the disease with depression, stating that “diabetes is caused by melancholy.”

English physician Thomas Willis was the first Western doctor to figure out the connection between diabetes and sugar in the urine.

How did early doctors “test” for diabetes in patients?

Around 1670, Thomas Willis announced the rediscovery of the connection between diabetes and the sweetness of the patient’s urine, although the symptoms of the disease had already been noted earlier by the Egyptians, Chinese, Greeks, and Indians. Doctors who knew about the disease-it had yet to be understood-would then diagnose the disease by tasting a patient’s urine. This is because when the blood glucose levels in a person rise, the body takes out water from the cells’ tissues and eliminates the sugar through the urine. As time went on, not all doctors used the modern tests, often discovering the disease in a patient through tasting the urine. It was even, as some reports mentioned, noticed by observation. For example, one report stated that in the 1800s, an incontinent person with diabetes and on his or her deathbed would often attract black ants.

Who was Matthew Dobson?

English physician and experimental physiologist Matthew Dobson (1732–1784) was the first to discover, in 1775, that sugar was the sweet substance in the patients with diabetes (caused by hyperglycemia). His work, Experiments and Observations on the Urine in Diabetics (1776), did not have a great impact on the medical community. He also noted that diabetes was not associated with the kidneys, as many physicians believed at that time.

What is polyuria?

Polyuria is when a patient urinates excessively, usually producing dilute urine. This excessive urination is often one of the first symptoms of uncontrolled diabetes, especially of type 1 and type 2 diabetes, in both children and adults. This symptom was known by many early physicians before the main reasons for diabetes were understood.

Who was Michel Chevreul?

In 1815, Michel Eugène Chevreul (1786–1889), a French chemist, showed that the sugar or sweetness in the urine of a person with diabetes came from what he termed “grape sugar.” It is what is now known as glucose. In Chevreul’s time, the finding was an important step toward understanding diabetes.

What did early doctors think caused diabetes?

Diabetes was not well understood until the early 1900s. Before then, there were many suggestions as to the cause. For example, many doctors believed the disease was just an imbalance in the body. They believed the reason for a patient’s experiencing excessive urination, profuse sweating, and often vomiting was that the body was trying to get back into balance again.

What were some early common treatments for patients with diabetes?

Because diabetes was so misunderstood, there were many treatments that seem bizarre and even dangerous by today’s standards. One of the most popular treatments was commonly used for almost all diseases in the 1800s-the practice of bleeding the patient. Others included having the person fast (many times to near starvation), having him or her eat excessive amounts of sugar, giving the person only the meat and fat of animals to eat, or feeding him or her specific herbs that were thought to cleanse the body of diabetes.

Who were Jean De Meyer and Edward Sharpey-Schäfer?

English physiologist Edward Albert Sharpey-Schäfer (1850–1935) was the first scientist to suggest that the pancreas was connected to blood sugar levels in the body. He was also the first person to discover adrenaline and inferred the existence of “insuline,” the term he used for what is now called insulin. Several years before, Belgian clinician and physiologist Jean-Egide-Camille-Philippe-Hubert De Meyer (1878–1934) worked on pancreatic secretions and also suggested the name “insuline”-the original French-13 years before the hormone was isolated. Sharpey-Schäfer was apparently unaware of De Meyer’s work.

As early as 1895, Sharpey-Schäfer theorized that glucose came from the pancreas and originated in the islets of Langerhans. He also suggested several ideas about the nature of insuline, including that it may be an enzyme that the body uses to metabolize glucose. The theory he preferred was that insuline may inhibit the breakdown of glycogen, and if the liver did not have this “inhibitor,” it would no longer store glucose, causing it to spill into the body’s circulation.

Who discovered the connection between the islets of Langerhans and diabetes?

American physician and pathologist Eugene Lindsay Opie (1873–1971) was the first to discover the relationship between the islets of Langerhans (found in the pancreas) and diabetes. After examining postmortem patients who had developed diabetes, he correctly assumed that degenerative changes in the tissues of the pancreas (or islets of Langerhans) caused the diabetes. Along with his diabetes-and-pancreas discoveries, Opie was also known for his research on the causes, transmission, and diagnosis of tuberculosis (TB) and worked on immunization against the disease. He was also the first to suggest that an obstruction at the junction of the bile and pancreatic ducts was responsible for acute pancreatitis.

Which researchers are credited with discovering insulin?

The credit for the discovery of insulin most often goes to Canadian physician Frederick Grant Banting (1891–1941), Scottish biochemist and physiologist John James R. Macleod (1876–1935), and Canadian medical scientist Charles Best (1899–1978). Although earlier researchers had suggested that the pancreas secreted a substance that controlled the metabolism of the body’s blood sugar, it was not proven until 1922, when Banting, Macleod, and Best announced their discovery. In 1921, they had begun experimenting on dogs, removing the animals’ pancreases, essentially making the dogs diabetic. They would then grind down the animals’ organs and extract a solution they called isletin. Injecting the solution into other animals resulted in a drop in blood sugar levels. By January 1922, they formulated an extract-this time from cattle pancreases-to try on humans with type 1 diabetes (see Leonard Thompson, below). When Thompson had an allergic reaction, Canadian biochemist James Bertram Collip (1892–1965) worked for about 11 straight days, making the injection more “pure” for humans. The new solution worked, and after several more patients were treated successfully, insulin eventually became one of the best treatments for people with diabetes.

Did any other researchers come close to discovering insulin?

Yes, several other researchers came close to discovering, extracting, and developing insulin. The list is long and often confusing. Some people claim that certain researchers came close but did not understand what they were witnessing. Other historians believe certain researchers should have been given more credit for their discoveries. And there is also a political, social, and infighting aspect of science in the early days before, during, and even after the first insulin trials. The following lists some of the more well-known cases in the history of insulin (and some of these events are often highly debated by historians):

Canadian physician and Nobel laureate Frederick Banting was co-discoverer of insulin.

In 1889, two European researchers, German physiologist and pathologist Oskar Minkowski (1858–1931) and German physician Joseph Freiherr von Mering (1849– 1908), working at an institute in Strasbourg headed by an authority on diabetes, German pathologist Bernhard Naunyn (1839–1925), discovered that when the pancreas was removed from dogs, the animals would develop symptoms of diabetes. The researchers suggested that the pancreas was crucial to the body’s sugar regulation and metabolism.

American physiologist Ernest Lyman Scott (1877–1966) conducted blood-sugar experiments on dogs. If a dog’s pancreas was removed, he noticed the animal’s blood sugar would rise. He then isolated secretions from the pancreas (what is now known as insulin) and injected the dog, causing its blood sugar level to lower. Thus, he is often credited as the first person actually to extract insulin (in 1911; insulin for medical use was introduced in 1923). In addition, he is most well known for developing the standard blood test for diabetes in 1914.

Romanian physiologist and professor of medicine Nicolas Constantin Paulescu (also seen as Paulesco; 1869–1931) worked to identify the active pancreatic substance that Minkowski and von Mering suggested could be used to treat diabetes. In 1916, he isolated the substance and called it “pancrein,” or what is now called insulin. Thus, Paulescu is often suggested as the discoverer of insulin (and why some researchers believe Paulesco and Scott should have been credited with discovering insulin).

But in the end, the Nobel Prize in Physiology or Medicine in 1923 was awarded to Banting and Macleod, as they were the first known actually to develop insulin for human use. (Banting shared his half of the prize with Best, while Macleod shared his half of the prize with Collip.)

Who was Elizabeth Evans Hughes?

Elizabeth Evans Hughes (later Gossett; 1907–1981) developed type 1 diabetes at age 11. She was the daughter of Charles Evans Hughes (1862–1948), a former governor of New York, an associate justice of the Supreme Court of the United States, and a presidential candidate (he was defeated by Woodrow Wilson), among other political accomplishments. At the time Elizabeth was diagnosed, most people who had untreated type 1 diabetes only lived about a year after diagnosis. In addition, most treatments included a starvation diet. Elizabeth was put on such a diet, going from around 75 pounds (34 kilograms) to 45 (20.4 kilograms) in three years. Eventually, Frederick Banting agreed to take Elizabeth on as a private patient. Determined to get well even though the disease was destroying her health, she became one of the first patients treated with the “new” medication for diabetes-insulin. She recovered quickly and was eating a normal diet within two weeks. (For more about Banting and insulin, see above.)

Who was Leonard Thompson?

In January 1921, Leonard Thompson (1908–1935) was the first person with type 1 diabetes to receive an injection of insulin. He was 14 years old at the time and weighed a mere 65 pounds (27 kilograms). The insulin was created by Macleod, Banting, and Best (see above) and was reported to be “a murky, light brown liquid containing much sediment,” a far cry from what insulin is like today. Thompson had an allergic reaction to the first shot. But after James Collip (1892–1965) removed many of the contaminants, the cattle-extracted solution was successful, resulting in Thompson’s sugar levels returning to “normal.” Thompson would continue taking insulin for the rest of his life. He died at age 27 of pneumonia, thought to be a complication from his diabetes.

Why was it so difficult to make insulin long ago?

Overall, insulin was difficult to manufacture in large quantities, and there was also a problem with contamination of the insulin. In addition, at that time, there were about one million Americans with type 1 diabetes. Not only was there a low quantity and quality of insulin, there were also problems matching a correct dosage to a person.

Which company made the first commercial insulin?

The company responsible for making the first commercial insulin was Eli Lilly. In 1922, in collaboration with MacLeod, Banting, Best, and Collip (who realized they could not commercially produce their insulin in large quantities), the company put the new drug through more than 100,000 tests. By April 1923, the company was producing more than 180,000 units of insulin per week, although the overall preparations were difficult (they used cattle and porcine pancreas glands).

Who was the first person to crystallize (purify) insulin?

Because the first human insulin preparations were so impure, there was a need to isolate a pure form of the hormone. The first person to develop such a pure insulin-also called crystallized insulin-was American biochemist John Jacob Abel (1857–1938) in 1926. Abel was also the first person to purify adrenaline (originally discovered by Edward Sharpey-Schäfer; see above), a substance he called epinephrine, and first to invent a primitive artificial kidney.

Who was Sir Harold Himsworth?

Sir Harold Percival Himsworth (1905– 1993) is thought by many historians to be the first to describe diabetes as a syndrome. Other earlier physicians had mentioned the possible connection between late-onset diabetes and obesity, hypertension, and arterial diseases. But Himsworth was the first to mention the syndrome in his 1949 Lancet paper “The syndrome of diabetes mellitus and its causes.”

American pharmacologist John Jacob Abel was the first scientist to purify insulin.

Who was Elliot Joslin?

Elliot Joslin (1869–1962) is credited as one of the first diabetes researchers to uncover the association between obesity and diabetes and one of the first physicians to specialize in diabetes. In addition, in the 1930s, he was the first to note the association between diabetes, hypertension, and arterial disease. He was the founder of the Joslin Institute, a premier research institute specializing in diabetes. (For more about the Joslin Institute, see the chapter “Resources, Websites, and Apps.”)

When was the true structure of insulin determined?

The full structure of insulin, called a peptide hormone, was discovered in 1955 by British biochemist Frederick Sanger (1918–2013). It was the first protein to be fully sequenced (or determining DNA bases in a genome; for more about genomes and DNA, see the chapter “Other Types of Diabetes”). Sanger won the Nobel Prize in Chemistry in 1958 for his research on insulin (he also won a Nobel Prize in Chemistry in 1980, one of only two people ever to have done so in the same category).

What were the steps to developing synthetic insulin?

Research shows that once a protein’s sequence is known, it is possible (in theory) to make the same thing synthetically. Thus, in 1963, insulin was the first protein to be chemically synthesized in the laboratory. But it was still difficult to produce enough of the insulin for the million or more people with diabetes. By 1978, insulin became the first human protein to be manufactured through biotechnology. It was first synthesized by American geneticist Arthur Riggs (1939–) and Japanese molecular biologist and chemist Keiichi Itakura (1942–) using E. coli bacteria with recombinant DNA technology. The City of Hope National Medical Center (to date, Keiichi Itakura still works at the center), along with the biotechnology company Genentech, synthesized the first human insulin in a process that could produce insulin in large amounts. In order to do this, the researchers inserted a gene for human insulin into bacterial DNA and used the bacteria as minifactories to make the A and B chains of the protein separately. Then a chemical process combined them. This procedure created a more “human-userfriendly” type of insulin, which was much more stable than animal insulin. Most insulin-dependent people with diabetes now use recombinant human insulin instead of animal insulin.

Why did so many people hide their diabetes diagnosis long ago?

It is hard to say why so many people once hid their diagnosis of diabetes. In fact, it was often called an “invisible” disease because most people showed no symptoms, and many chose to hide their condition. Some of the reason was no doubt cultural (often called the “stiff upper lip” syndrome), and many people with the disease did not want others to know they were not healthy. Before the availability of insulin, having the disease often meant a quick death. Other times, because the disease was not well understood, many people did not know whether the disease would spread. All this, and no doubt more, led people to hide their diagnosis of diabetes. Through research and education in the last half century, the disease-although still not fully understood-does not have the same stigma as in earlier times.

Before synthetic insulin was invented, pigs like this one had been used to produce insulin for humans with diabetes, since their insulin is quite similar to a person’s.

Which animals were used for insulin in the past?

Long before synthetic insulin was available, insulin for human use was usually derived from animals, especially pigs and cattle. For example, the amino-acid sequence of pig and human insulin are almost identical, but not exact: pigs’ insulin differs from humans’ by one amino acid, and cattle (bovine) insulin differs by three amino acids. But in the 1920s, no one knew the details of genetic sequencing. Thus, the researchers were fortunate that the various animal species’ insulin used were almost the same as in humans (although sometimes there were adverse reactions to the animal-extracted insulin, such as skin rashes).

What is Humalog®?

Humalog® is a commercially available-by prescription-modified human insulin. It was approved by the Food and Drug Administration in 1996 and was specifically developed to be active quickly after injection by quickly lowering levels of blood glucose (thus it is called a rapid-acting insulin). It is mostly used to treat type 1 diabetes in adults and usually given with long-acting insulin. Humalog® (also referred to as “insulin lispro injection”) is manufactured much like Humulin®, as it is produced by recombinant DNA technology (using a strain of E. coli or Escherichia coli).

When was the first synthesized human insulin available?

The first human insulin to be synthesized was called Humulin®, manufactured by a technique known as recombinant DNA (or the inserting of human genetic instructions into a bacterium that then produces the drug). It was approved by the Food and Drug Administration in 1982 but was not marketed-and thus was not widely available-until 1983. It is almost, but not exactly, identical to the insulin produced by the human pancreas, and for the most part, it acts in the same way as the body’s own natural insulin. Humulin® is also considered a rapid-acting insulin (it takes a relatively short time to become active in a person’s bloodstream after taking it, compared to some other types of insulin; for more about the various types of insulin, see the chapter “Taking Charge of Diabetes”).

Why was insulin considered “the cure” for so long-and why has thinking it was a “cure” been somewhat detrimental to diabetes research?

When insulin was finally discovered and commercially available, it seemed to most people-especially those who did not have diabetes-to be “the cure” for the disease. But as many people now know, while insulin has helped many people for years, it is not the only solution to diabetes (type 1, type 2, and all other types) problems. As one researcher mentioned after insulin was discovered, it appeared that diabetes research was almost forgotten. But there are so many other aspects of the disease (such as the many complications, including kidney disease) and other treatments that should be investigated (such as islet transplantation or development of an artificial pancreas). Thus, many researchers say that the “cure” should never have been about insulin alone.


What are the ten leading causes of death in the United States?

According to the U.S. Centers for Disease Control and Prevention (CDC), the top leading causes of death in the United States were as follows as of 2014 (listed in a report in 2015)-and included diabetes:

1. Heart disease (also called ischemic heart disease)

2. Cancer (malignant neoplasms)

3. Chronic lower respiratory disease

4. Accidents (unintentional injuries)

5. Stroke (cerebrovascular diseases)

6. Alzheimer’s disease

7. Diabetes (diabetes mellitus)

8. Influenza and pneumonia

9. Kidney disease (nephritis, nephritic syndrome, and nephrosis)

10. Suicide (intentional self-harm)

Annually, and on average, these ten causes account for nearly 75 percent of all deaths in the United States. In fact, this list has not changed much in several years.

Is diabetes truly the seventh leading cause of death in the United States?

Yes, it is, but in some ways, it should be considered the third leading cause of death. The numbers-seventh or third-are true, but they are dependent on whether people who die from related cardiovascular disease are included. In other words, just diabetes alone accounts for the listing as seventh, whereas diabetes and the often-resulting cardiovascular disease (heart problems in particular) would make diabetes third on the list.

What percentage of people have prediabetes in the United States?

According to the Centers for Disease Control and Prevention (CDC), in 2014, almost 80 million Americans were thought to have prediabetes (also written as pre-diabetes). By 2016, it was estimated that the number had grown to 86 million, but only about 11 percent of prediabetic people realize they have prediabetes. The CDC also suggests that 70 percent of those who have prediabetes (and know it) will go on to develop type 2 diabetes if they do not take care of themselves. In other words, many Americans are ignoring the signs and symptoms of prediabetes and will eventually develop type 2 diabetes. This outcome will, in turn, put a major strain on public health and the health care system-not to mention inflict a possible emotional and most likely economic toll on people and their families.

How many people have diabetes in the United States?

According to Harvard Medical School, to date, there are nearly 26 million Americans with diabetes (mainly type 1 and type 2)-a number that has almost doubled in just over a decade. It is estimated that another 86 million adults have elevated blood sugar levels and are at a higher-than-normal risk for developing diabetes (prediabetes). Thus, overall, it is estimated that one in three Americans has diabetes or has a high risk for developing it.

What percentage of the United States population has type 1 diabetes?

According to the International Diabetes Federation, to date, around 5 percent of the people in the United States with diabetes have type 1 diabetes. Because it is estimated that there are around 26 million Americans with diabetes, “5 percent” means that over 1 million people have type 1 diabetes in the United States (another estimate is that 1.25 million Americans have type 1 diabetes).

According to several statistics from various diabetes organizations, more than 40,000 cases of type 1 diabetes are reported per year in the United States, and that number continues to grow. It is also estimated that by the year 2050, there will be 5 million people in the United States with type 1 diabetes, with nearly 600,000 of them less than 20 years of age.

How many American children and adults are thought to have type 1 diabetes?

Although type 1 diabetes is most often associated with children, it also can affect adults (for more about adult type 1 diabetes, see the chapter “Type 1 Diabetes”). According to the JDRF (formerly the Juvenile Diabetes Research Foundation), of the 1.25 million Americans who have type 1 diabetes, 200,000 are young (under 20 years old) and over a million are adults (20 and older).

How fast has the number of diabetics in the United States increased over the past 25 years?

According to Harvard Medical School, statistics have shown that the number of Americans with diabetes (all types) has grown sharply-some estimates say doubled in number in just over a decade. It is also estimated that more than 90 percent of the people who have diabetes have type 2 diabetes.

Which one of the largest U.S. cities has the highest diabetes rate?

According to a study conducted at Drexel University in 2014, Philadelphia has the highest diabetes rate among the nation’s largest cities. In addition, the county where Philadelphia is located is considered to have one of the worst health conditions of any county in the state. A study from the journal Advances in Preventive Medicine found in surveying more than 17,000 participants in the Philadelphia area that living in a disadvantaged neighborhood seemed to play a major role in a person’s risk of developing diabetes. Researchers said focusing on the individual to curtail the number of people with the disease in this region would not be as effective as concentrating on the education-and thus the health-of the overall community.

How much is spent on diabetes care each year in the United States?

According to the most recent data (2012), it is thought that spending on diabetes and its care costs more than $245 billion per year in the United States alone-a record high (and it is no doubt even higher as of this writing). Of that, $176 billion went for such diabetes-associated items as medications and emergency care. In fact, in 2010, almost 10 percent of all emergency-room visits in the United States were by people with diabetes-related conditions, such as nerve damage, eye trouble, and kidney and circulatory problems.

What are the four leading causes of death worldwide?

According to the World Health Organization, in 2012 (the most recent data was updated in 2014), ischemic heart disease, stroke, lower respiratory infections, and chronic obstructive lung disease were the top major killers worldwide. In fact, this four-causes list has remained the same for the past decade. (The lung-related ailments were listed at around 3.1 million deaths per year.) Even though this short list does not include diabetes, heart disease is often found in connection with diabetes. (Diabetes was listed as the eighth leading cause at 1.5 million deaths per year.)

How many people around the world are thought to have prediabetes?

According to the International Diabetes Federation, in 2013 (the latest data from IDF), around 316 million people have what is called impaired glucose intolerance (or impaired fasting glucose), or prediabetes. This number has grown significantly in the past decade.

Has the number of deaths from diabetes increased worldwide?

Yes, according to data from the World Health Organization (WHO), diabetes caused around one million deaths in the year 2000. In 2012 (updated in 2014), the number increased, with diabetes causing around 1.5 million deaths. (Note: These numbers do not distinguish between people with type 1 or type 2 diabetes.)

How many people die of diabetes-related complications around the world each year?

The statistics concerning how many people die of diabetes-related complications around the world each year would fill many pages of this book. Such information can be found on several diabetes-education websites, such as the International Diabetes Federation (www.idf.org). For example, in 2013, the IDF estimated that 5.1 million people died of diabetes-related complications worldwide.

Why is it difficult to estimate the number of people with diabetes around the world or for specific countries?

Probably the main problem when estimating how many people have diabetes is that there is no national registry or database for the disease in most countries or even an international database (unlike for some infectious diseases or even for such conditions as Lyme disease). In addition, many reports of deaths from diabetes are actually couched in terms of secondary diseases, such as heart or kidney failure (which can be from diabetes but are listed only as heart or kidney failure). Thus, many organizations that present statistics on how many people have diabetes may be underestimating the disease.

Over half a million children worldwide have type 1 diabetes.

How many children around the world have type 1 diabetes?

It is estimated that 542,000 children worldwide have type 1 diabetes. Of this number, about 200,000 live in the United States, according to the JDRF (formerly called the Juvenile Diabetes Research Foundation). And it is thought that the numbers will keep rising around the world. For example, according to the International Diabetes Federation, more than 79,000 children developed type 1 diabetes in 2013. This number was up from 77,800 in 2011.

Which continent has the highest number of children with type 1 diabetes?

According to the International Diabetes Federation, the European continent has the highest number of children with type 1 diabetes. It is not known why this is so, but some researchers suggest that it may be due to one or more environmental, genetic, or dietary factors.

How many people have diabetes in the United Kingdom?

As of this writing, it is estimated that 3.2 million people in the United Kingdom have diabetes. It is estimated that the number will reach 5 million people by the year 2025.

Why do some researchers believe sugar may have a direct link to diabetes in other countries?

In a study conducted in 2013, researchers suggested that the amount of sugar sold in a country may have a close link to diabetes. In particular, the study examined data of global sugar availability and diabetes rates from 175 different countries over the past ten years. They found that as the sugar in certain countries’ food supplies increased (and therefore, consumption increased), there were higher type 2 diabetes rates. In addition, they found that the longer a population was exposed to excess sugar, the higher the diabetes rate. The study’s statistical methods controlled for factors such as obesity rates, calories available per day, percentage of the population age 65 or older (as age is associated with increased diabetes risk), and so on. Thus, because of this study, some researchers suggest that sugar may affect the liver and pancreas in ways that other types of foods or obesity do not.

Of course, not all researchers agree. Many believe that obesity has a direct and major effect on a person’s predisposition toward type 2 diabetes, along with total calorie intake. This study, too, does not prove that sugar causes diabetes-either type 1 or 2. But it does add more data to the quandary faced by many researchers who are trying to understand why there has been such an increase in the number of people worldwide who have diabetes. (For more about sugar in the diet and diabetes, see the chapter “Diabetes and Eating.”)

What is the estimate as to how many people with diabetes die of heart disease or stroke?

According to the American Diabetes Association, it is estimated that more than 65 percent of people with diabetes die of heart disease or stroke. But the association also notes that if people with diabetes manage their blood pressure and cholesterol-along with their blood glucose levels-they can greatly reduce their risk of both heart disease and stroke.

How many people are afflicted by diabetes around the world-and will be affected in the future?

In 2015, the International Diabetes Federation estimated that there were 415 million adults with diabetes around the world, or one person in 11 has the disease. This is merely an estimate, as it is thought that one in two adults (or around 46.5 percent) with diabetes is undiagnosed. The organization also estimates that by the year 2040, around 642 million people-or about one person in ten-will have the disease.

Of course, like many statistics, numbers reported depend on the organization. For example, in 2016 the UN World Health Organization released its figures: 422 million adults around the world-or one in 11 people or 8.5 percent of the population-have diabetes. WHO also reported that in 2012, 1.5 million deaths were caused by diabetes, with higher-than-optimal blood glucose levels causing an additional 2.2 million deaths that year, mainly by the increased risk of cardiovascular and other diseases.

What are some of the reasons for the higher levels of type 2 diabetes around the world?

There is probably no one reason for the high levels of type 2 diabetes around the world, and many researchers mention several factors. For example, type 2 diabetes seems to be associated with higher levels of urbanization; an aging population; more sedentary lifestyles; and unhealthful diets (which often include a high sugar intake). In addition, according to the International Diabetes Federation, around 75 percent of people with diabetes live in low-and middle-income countries (but IDF does not list type 1 and type 2 diabetes separately).

Are treatments for diabetes available around the world?

Although most wealthy countries have a good supply of insulin available for people with diabetes, several do not. For example, according to the World Health Organization, essential diabetes medicines and technologies, including insulin, that are needed for treatments are mainly available in only one in three of the world’s poorest countries.

On average, how much is spent on diabetes around the world?

According to the International Diabetes Federation, in 2015, 12 percent of global health expenditures were spent on diabetes. By the year 2040, with the increase in the number of people with diabetes, it is estimated that the amount of global health expenditures for the disease will be around $802 billion (U.S.) per year.