What are the major organic molecules in humans?

The major organic (also called bioorganic) molecules in the human body are carbohydrates, lipids (or fats), proteins, and nucleic acids. These molecules are characteristic of all life-from the smallest to largest cells. They all have basic roles in the body’s cells, such as storing and producing energy, providing structural materials within a cell, and storing hereditary information. (For more information about carbohydrates, lipids, and fats, see the chapter “Diabetes and Food.”)

Are glucose levels affected by carbohydrates, fats, and proteins?

Yes, glucose levels in the body are affected by what a person eats, whether the foods contain carbohydrates, fats, or proteins (along with vitamins, minerals, and other nutrients). All of these bioorganic molecules can affect people’s glucose levels whether they have diabetes or not-albeit in different ways.

What is an enzyme?

An enzyme is a protein that acts as a biological catalyst. It decreases the amount of energy needed (activation energy) to start a metabolic reaction. Different enzymes work in different environments, owing to changes in temperature and acidity. For example, the amylase enzyme that is active in the mouth cannot function in the acidic environment of the stomach; pepsin, which breaks down proteins in the stomach, cannot function in the mouth. In fact, without enzymes, the stomach would not be able to obtain energy and nutrients from food. In the human body, there are thousands (ranging from 1,000 to 5,000 depending on the source of information) of enzymes that help with cellular reactions.

What are proteins, and what is their purpose?

Proteins are large, complex molecules composed of smaller subunits called amino acids. Human life could not exist without proteins, as these complex molecules help build, maintain, and repair the body and especially the body’s cells.

What are some important enzymes-or proteins-in the human body?

The enzymes that are required for all metabolic reactions are proteins. These proteins also are important to structures such as muscles, and they act as both transporters and signal receptors. The following lists the types of proteins and examples of their functions, including those associated with blood glucose:

Type of Enzyme/Protein

Examples of Functions


Antibodies that respond to invasion


Increase the rate of reactions; build and break down molecules


Insulin and glucagon, which control blood glucose levels


Cell-surface molecules that cause cells to respond to signals


Store amino acids for use in metabolic processes


Major components of muscles, skin, hair


Hemoglobin carries oxygen from lungs to cells


What is an autoimmune disease?

An autoimmune disease is one in which the body triggers an immune response against its own cells and tissues. Autoimmune diseases can affect almost every organ and system in the body. The cause or causes of most autoimmune diseases is unknown. They may be systematic (meaning they affect and damage many organs) or localized (affecting only a single organ or tissue). The following lists only a few autoimmune diseases that affect certain body systems (those associated with diabetes are italicized):

Autoimmune Diseases and Their Effects

Body System

Autoimmune Diseases

Blood and blood vessels

Autoimmune hemolytic anemia; pernicious anemia; systemic lupus; Wegener’s granulomatosis

Digestive tract

Autoimmune hepatitis; Crohn’s disease; scleroderma; ulcerative (including the mouth) colitis


Sjögren’s syndrome; type 1 diabetes mellitus


Graves’ disease; thyroiditis; type 1 diabetes mellitus


Myocarditis; rheumatic fever; scleroderma; systemic lupus


Rheumatoid arthritis; systemic lupus erythematosus


Systemic lupus erythematosus; type 1 diabetes mellitus


Rheumatoid arthritis; scleroderma; systemic lupus erythematosus


Myasthenia gravis; polymyositis

Nerves and brain

Guillain-Barré syndrome; multiple sclerosis; systemic lupus erythematosus


Psoriasis; scleroderma; systemic lupus erythematosus

Besides diabetes, what other illnesses are often caused by the body’s own immune system’s “attacking” itself?

One explanation for the development of type 1 diabetes is thought to be the immune system’s antibodies attacking the insulin-producing cells in the pancreas. But this is not the only way the body’s immune system “mutinies” against itself-attacking the organs it is supposed to defend. For example, autoimmune diseases include rheumatoid arthritis, in which antibodies attack the tissues of the joints. Another is multiple sclerosis, which is thought to be caused when antibodies attack the myelin sheath surrounding nerves. (For more about arthritis and diabetes, see the chapter “How Diabetes Affects Bones, Joints, Muscles, Teeth, and Skin.”)

What is the difference between inflammation and infection?

Inflammation does not mean infection, even when the infection causes the inflammation. An infection is caused by a bacteria, fungus, or virus, while an inflammation is the body’s response to the infection.

Scleroderma is an autoimmune disease affecting the skin, in many cases, but it can also afflict internal organs such as the lungs and kidneys.

Do people with diabetes often have more infections?

Yes. Because high blood glucose levels can weaken a person’s immune system-along with damaging nerves and reducing blood flow-people with diabetes are more apt to have infections. These include infections of the skin (in particular the feet), bladder, kidney, and mouth, and for women, often vaginal infections.

Do older people with diabetes seem to have more infections?

Yes, according to some studies, older people with diabetes seem to get more infections. In particular, common sites of such infections include the urinary tract, along with the skin (mostly areas that remain moist; for instance, the groin and armpits), and the soft structures (for example, between the toes) and bony structures (such as with bunions) of the feet. There are several reasons for more of these infections in the elderly, especially a less-efficient immune system, traumas, neuropathies, and infections that go unnoticed or are ignored by the person.

Which skin cells are involved with the immune system and deterring infections?

Keratinocytes, found in the top layer of skin called the epidermis, assist the immune system. They produce hormone-like substances that stimulate the development of certain white blood cells called T lymphocytes. In turn, the T lymphocytes defend against infection caused by disease-causing pathogens-mainly bacteria and viruses. (For more about the skin, see the chapter “How Diabetes Affects Bones, Joints, Muscles, Teeth, and Skin.”) For people with diabetes, defense against infections is often less efficient, as high blood glucose levels often weaken their immune system.

What are the types of immune responses in the body?

The body has two major forms of ridding the body of disease or invading microbes that result in inflammation. Natural (or innate) immunity operates against microorganisms and dead cells and cell parts and is usually present when a person is born. The body’s acquired immunity responds to the presence of specific antigens (toxins, often) and is usually acquired after birth as the body is exposed to certain antigens as the person ages. For example, if a person gets a splinter, the tissue around the entry wound becomes irritated, hot, painful, red, and swollen. This is the result of the body’s immune response to fight off the microorganisms that are on the splinter. In this case, the body’s immune system sends out what are called phagocytes, or cells in the blood that (if working properly) approach their prey, engulf it, and destroy it with special enzymes.

What is the role of fever in infection?

T he normal body temperature for humans is 98.6°F (37.2°C), although this can vary up or down by a few degrees. A fever is defined as a higher-than-normal body temperature, and it most often occurs when certain pathogens (a bacterium, virus, or other microorganism that causes disease) invade the body. For example, bacteria often release certain toxins when they invade the body, many of which cause an infection. These toxins (or antigens) cause the body’s immune system to respond by releasing special proteins that regulate body temperature. The increase in body temperature also causes a person’s metabolic rate to rise and speeds up the body’s reactions that aid in getting rid of infection. One of these includes a fever, which seems to inhibit the growth of certain microbes. It also stimulates the liver to hoard certain substances that bacteria seem to require, which helps to stop the microbes from growing.

What is inflammation in the human body?

Inflammation (from the Latin inflammo or “ignite”) is the body’s natural way of fighting off microbes that enter the body; it is also referred to as part of the body’s immune response. It is a positive feature, as it is the body’s attempt to protect itself against harmful stimuli and to begin healing. But it can also cause more inflammation, becoming almost self-perpetuating.

Most people are familiar with inflammation. For example, the body responds to a bug bite, rash, or skin infection-all of which cause inflammation in the infected area. Inflammation can be acute, meaning it starts rapidly and quickly becomes severe, such as when a person accidentally cuts a finger with a knife. Inflammation can be chronic, meaning long-term inflammation that can last months or several years. This type of inflammation can cause several diseases and conditions, including atherosclerosis, periodontitis, hay fever, and rheumatoid arthritis. And although scientists know that inflammation can play a role in, for example, heart disease and possibly diabetes, it is still unknown what drives inflammation in the first place.

What is the connection between inflammation and diabetes?

There seems to be a connection between inflammation and, in particular, type 2 diabetes. Recent studies seem to indicate that inflammation inside the body may actually play a role in the development of type 2 diabetes. Some research indicates that fat may be the problem, especially in people who are obese and have fat around the belly. It is thought that these fat cells produce chemicals that lead to inflammation, which some researchers believe contributes to the development of chronic diseases such as type 2 diabetes.

In fact, it is known that people who have type 2 diabetes have higher levels of inflammation in their bodies, including higher cytokines, or inflammatory chemicals in the body. It is also known that they also have elevated cytokine levels inside their fat tissues. Thus, excess body fat probably causes chronic, low levels of inflammation in a person with type 2 diabetes, altering the insulin’s ability to do its normal task and further contributing to the disease. This does not mean that inflammation causes type 2 diabetes, but it appears to be involved in the development of the disease.

Why is exercise good to fight inflammation and type 2 diabetes?

It is thought that physical exercise-even 30 minutes of walking a day-may not only help prevent type 2 diabetes in those who are at risk of developing the disease but may also help increase insulin sensitivity. This is because exercise releases several anti-inflammatory chemicals into the body. It also helps the body’s muscle (and other) cells increase their sensitivity to insulin and, in turn, helps reduce chronic inflammation.

Walking 30 minutes a day is a good way to help stave off the possibility of contracting type 2 diabetes.

What is the inflammatory factor (IF)?

The inflammatory factor (IF), described almost a decade ago, is a way of rating foods based on their potential ability to increase or decrease inflammation in the body. The numbers in the range vary widely (there are no upper or lower limits), and each rating is considered to be dependent on serving size. Most studies on the IF have shown a mixed result, and the topic is highly debated. Some people say there is no way to control inflammation in our systems using this method, while others believe eating foods with the IF in mind will help decrease inflammation in the body.

What is an anti-inflammatory diet, and can it help a person with type 2 diabetes?

An anti-inflammatory diet is just as the phrase implies: Some foods have natural anti-inflammatory properties and attributes. Eating such a diet does not prevent type 2 diabetes, but it does help with weight loss-a contributor to the disease for people at high risk for developing type 2 diabetes. The foods often mentioned include fats such as omega-3 fatty acids (olive, flaxseed, and canola oils), avocados, walnuts, and most fruits and vegetables (oranges, tomatoes, leafy greens, blueberries, etc.). Foods that can cause inflammation are those that contain trans-fatty acids, vegetable shortening, red meat (especially beef and pork), and margarine. (For more about foods and diabetes, see the chapter “Diabetes and Food.”)


What is the difference between human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS)?

The term AIDS (acquired immunodeficiency syndrome) applies to the most advanced stages of HIV (human immunodeficiency virus) infection. According to the Centers for Disease Control and Prevention, AIDS includes all HIV-infected people who have fewer than 200 CD4+ T cells per cubic millimeter of blood. (Healthy adults usually have CD4+ T cell counts of 1,000 or more.) The HIV definition also includes 26 clinical conditions (including many infections that occur as complications of the disease) that affect people with advanced HIV.

How is HIV diagnosed?

The only accurate way to diagnose HIV is through antibody testing. The immune system of an individual infected with HIV will begin to produce HIV antibodies to fight the infection. Although these antibodies are ineffective in destroying the HIV virus, their presence is a positive indication of the presence of HIV.

How is the HIV virus transmitted from one person to another?

HIV is transmitted via unprotected sexual contact with an infected partner or through contact with infected blood. Over the past few decades, rigorous screening of the blood supply and heat-treating techniques for donated blood have reduced the rate of transmission via blood transfusions to a very small percentage. However, sharing needles and/or syringes with someone who is infected is still a mode of transmission of the HIV virus. In the past, HIV was frequently passed from a mother to her baby during pregnancy and/or birth. Treatments are now available that reduce the chances of a mother’s passing the virus to her child to 1 percent.

HIV is not transmitted through casual contact such as kissing or hand holding. Instead, there needs to be direct contact with another person’s blood, such as through a needle or as can happen through unprotected sexual intercourse.

Why should people with diabetes and AIDS be aware of infections?

The immune system of individuals with AIDS is severely compromised and weak, so the body cannot fight off certain bacteria, viruses, fungi, parasites, and other microbes. Because such infections can easily establish themselves, it is usually more difficult to fight off an infection for a person with HIV/AIDS who also has diabetes.

Why should a person taking metformin for diabetes, along with certain HIV medications, be aware?

According to the National Institutes of Health, people taking metformin for diabetes, plus getting certain HIV treatments, may be at higher risk of lactic acidosis (for more about lactic acidoses, see the chapter “Taking Charge of Diabetes”). They also warn that if a person has liver or kidney problems, or they binge drink or drink alcohol regularly, they are also at higher risk of lactic acidosis. As always, it is best for a person with diabetes and HIV to discuss medications, alcohol habits, and general health with their doctor.

Do HIV medications increase the risk of type 2 diabetes?

No, not all HIV medications increase the risk of type 2 diabetes, but according to the National Institutes of Health, some do. In particular, NIH says HIV medicines in the nucleoside reverse transcriptase inhibitor (NRTI) and protease inhibitor (PI) drug classes may increase the risk of type 2 diabetes. These include such drugs as didanosine (an NRTI) and indinavir (a PI) that seem to make it more difficult for the body to respond to and use insulin. This insulin resistance causes a rise in blood glucose levels that can eventually lead to type 2 diabetes. Thus, it is important to have blood glucose tests after starting these (and to be safe, other) HIV medications.

What should a pregnant woman with HIV be aware of in terms of gestational diabetes?

T he American Diabetes Association suggests that women who are pregnant and are being treated for HIV be screened early in their pregnancy by their doctor for gestational diabetes. This means around 24 to 28 weeks’ gestation or even earlier if the woman is taking certain HIV medications and/or if she has any other risk factors for developing diabetes.


Are women who have difficulty sleeping at risk for type 2 diabetes?

Yes, according to a study in 2016, women who have sleeping difficulties-both in quantity and quality of sleep-may be at an increased risk for type 2 diabetes. The study followed more than 133,000 women for ten years. Examining the women who developed type 2 diabetes, the researchers defined difficulty sleeping as: (1) trouble falling asleep or staying asleep; (2) sleeping less than six hours a night; (3) frequent snoring; and (4) either shift work disrupting sleep or sleep apnea. In most cases, these problems resulted in several conditions, including a higher body mass index (BMI; for more about BMI, see the chapter “Diabetes and Obesity”) that would indicate being overweight or obese, more hypertension (for more about hypertension, see the chapter “Diabetes and the Circulatory System”), less exercise, and depression.

Even without these conditions, the researchers showed, sleeping difficulties were still tied to a 22 percent increased risk for type 2 diabetes in the female participants. And if four of the above problems were prevalent, it meant the woman had almost four times the risk of developing type 2 diabetes. In this case, the explanation for the lack of sleep may be mostly hormonal. Sleep problems are often associated with the excess secretion of ghrelin (resulting in a boost in appetite) and cortisol (resulting in an increase in stress and insulin resistance), both of which increase the risk of type 2 diabetes.

Studies have shown that women who have trouble sleeping have an increased risk of getting type 2 diabetes. This may be because lack of sleep is the result of increased levels in the hormones ghrelin or cortisol, which are related to hunger and stress, respectively; and these, in turn, are related to diabetes risk.

What did a recent study show about A1c blood glucose levels and sleep duration?

According to a recent study, sleep and A1c blood glucose levels may definitely be linked. The researchers found that people with type 1 diabetes who slept less than an average of 6.5 hours a night had higher A1cs than those who slept longer (for more about A1c measurements, see the chapter “Taking Charge of Diabetes”). In addition to the finding of sleep length and A1cs, the researchers found that these shorter-term sleepers were “non-dippers,” or people who also have blood pressure levels that do not get lower at night-a definite indicator of health problems.

What is nocturnal hypoglycemia?

Nocturnal hypoglycemia is as the words indicate: a low blood glucose level during nighttime sleep. Often an episode of nocturnal hypoglycemia wakes a person, but sometimes it does not. If it does, it is often treated by the eating of fast-acting carbohydrates, such as glucose tablets or gel, to boost glucose levels back to normal. Thus, for safety reasons, most health care professionals suggest that a person with diabetes check his or her blood sugar at bedtime-and consider it one of the most important checks of the day.

What did a recent study find about insulin sensitivity and sleep duration in men?

In yet another recent study from the Netherlands, researchers found that there was a connection between insulin sensitivity and how long a male slept. Insulin sensitivity in this study was based on how sensitive a person is to the effects of insulin. High insulin sensitivity means less insulin is needed to lower blood glucose levels, whereas low insulin sensitivity means more insulin is needed to lower them. High or low sensitivity depends on how well the pancreas is producing or the body is using insulin. The researchers found that men who sleep for less than or more than seven or eight hours of sleep had lower insulin sensitivity. In addition, men who slept for shorter periods had lower beta cell function (beta cells produce and release insulin) in the pancreas. More research is needed because no one knows the real cause and effect.

What can occur if a person with diabetes has high or low blood glucose levels at night?

If a person with diabetes experiences high or low blood glucose levels at night, most of the time the episode has no effect, especially if the highs or lows are not too extreme. But if the levels become extreme, there may be certain problems if they are too high or low. For example, if people with diabetes have high blood sugar levels at night, it may be harder for them to sleep because they may feel too warm, irritable, and unsettled. If the levels are very low, it may cause problems within the person’s central nervous system, including nightmares, sleepwalking, restlessness, and confusion.

Why should a person with type 2 diabetes be aware of the “dawn phenomenon”?

Most people have a rise in hormones-for example, cortisol and glucagon-during the early hours of the morning, usually from about 2 A.M. to 8 A.M. Called the dawn phenomenon, it occurs as various organs attempt to keep a person’s blood glucose levels from going too low at night. This hormonal activity helps to tell the liver to produce more glucose. In response, there is an increase in insulin to handle the extra glucose. And this, in turn, allows a person to wake and start the day after fasting all night. But for a person with diabetes, such a rise in insulin may cause fasting glucose levels to be dramatically elevated as the system cannot handle the extra glucose.

Could daytime sleepiness be associated with lower blood glucose levels in type 2 diabetics?

Yes, some people with type 2 diabetes who have excessive sleepiness during the day could be at a higher-than-normal risk for hypoglycemia (low blood glucose levels). In a recent study, researchers speculated that when the blood glucose level dips low during nighttime sleep, it disrupts the diabetic person’s sleep, creating daytime sleepiness. In fact, that daytime sleepiness can make a person less aware of a hypoglycemia event during the day, thinking instead that he or she is just tired, and thus, a person who has not been diagnosed with diabetes may ignore the early warning signs of disease.

What is sleep apnea?

Sleep apnea, clinically called obstructive sleep apnea (or OSA, the most common form of sleep apnea), is a condition in which a person’s windpipe is temporarily closed as he or she sleeps, usually causing the person to pause his or her breathing. This commonly occurs when the upper respiratory airway is blocked, either because the throat muscles collapse, the tongue falls back into the airway, or the tonsils and/or adenoids are enlarged, impeding the air flow. The lapses in breathing also cause the individuals to wake up briefly because their breathing has been interrupted and may even stop for a brief period. Sleep apnea is often further described as a condition in which a person frequently stops breathing for ten seconds or more during sleep, with some experiencing a lack of breathing sometimes hundreds of times a night. A person who has apnea awakens frequently during the night gasping for breath. It is thought to be a medical problem for many reasons. For example, this pause in breathing can reduce the blood oxygen in the body, putting a strain on the cardiovascular system (especially the heart), which is why many people with sleep apnea are considered at risk for cardiovascular disease. It can also have an effect on a person with diabetes, causing a fluctuation in blood glucose levels during sleep (see below).

One symptom of type 2 diabetes can be a chronic feeling of being sleepy and tired.

Is there a connection between type 1 diabetes and sleep apnea?

Although it has not been investigated as much as sleep apnea in people with type 2 diabetes, recent studies have shown that people with type 1 diabetes may have more sleep apnea (and associated problems) than previously thought. For example, in 2015, a study showed that 67 people with type 1 diabetes had a high prevalence of obstructive sleep apnea. Sleep apnea was also associated with kidney complications and retinopathy (for more about the eyes and retinopathy, see the chapter “Diabetes and Inside the Human Body”). One interesting result of the study was that it was uncommon for people with type 1 diabetes and sleep apnea to be obese or have daytime sleepiness, which may be why a sleep apnea diagnosis was overlooked.

Who gets sleep apnea?

Sleep apnea (OSA) most often occurs when air cannot flow into or out of the person’s nose or mouth as he or she breathes. According to the National Sleep Foundation, sleep apnea often occurs in conjunction with snoring. And although snoring may be harmless for most people, it can be an indication of sleep apnea, especially if it is accompanied by mild to severe daytime sleepiness, which is why it is also often responsible for people’s having auto accidents owing to daytime grogginess.

Of course, most people who have sleep apnea may not know it as they are asleep when snoring or not breathing. Men seem to have apnea more than women, as do people who are obese, but it can occur in anyone at any age for various other reasons. For example, it can happen to people with a large neck, people with small airways (the nose, throat, or mouth), people who sleep on their backs, and people who have a misaligned jaw. Another cause can be that, as an individual ages, the muscles around the back of the throat become relaxed. One of the telltale signs of this condition is snoring. Another sign can be complaints of lack of sleep by the person’s bed partner.

Although there were few people in this study, other more recent studies are indicating the same results. For example, one study indicated that sleep apnea was higher in people who have been affected by type 1 diabetes the longest. Also, people with poorly controlled type 1 diabetes have more sleep apnea problems than those who have more control over their blood glucose levels. And, like people with type 2 diabetes and sleep apnea, people with type 1 often are fatigued and depressed, not only from lack of sleep but also from difficulty controlling their blood sugar levels both day and night.

Is there a connection between type 2 diabetes and sleep apnea?

Yes. Overall, it is estimated that up to 80 percent of people with diabetes-at this writing, mostly people with type 2 diabetes-have the condition. In particular, heavier people who have sleep apnea appear to have more health problems, including an increased risk for diabetes (no doubt because of being heavier or obese, which is connected to the risk of type 2 diabetes). If they already have type 2 diabetes, sleep apnea sufferers have difficulty controlling their blood sugar levels. For people with type 2 diabetes, sleep apnea also increases the risk of developing other diseases and conditions, including heart disease, high blood pressure, acid reflux, dementia, and depression.

What device may help stabilize blood sugar levels in people with sleep apnea (OSA) and type 2 diabetes?

In a preliminary study conducted in 2016, researchers found that people with diabetes who used a device called a continuous positive airway pressure (CPAP) device had improved blood glucose levels. The researchers evaluated the effects of a CPAP machine on people with both OSA and poorly controlled type 2 diabetes. They found that people using the CPAP experienced statistically significant improvements in insulin sensitivity at three to six months after using the device. There was also a decrease in insulin resistance and HbA1c levels at six months (for more about HbA1c, or A1c, testing, see the chapter “Taking Charge of Diabetes”). Another positive result was that the participants had lower levels of certain inflammatory molecules and LDL cholesterol (considered the “bad” cholesterol; for more about LDL, see the chapter “How Diabetes Affects the Circulatory System”), along with higher levels of adiponectin, a hormone involved in regulating blood glucose levels. But there are a few caveats: the number of people tested was small, and there was no placebo testing. Thus, more research is necessary to see whether the CPAP can truly help many people with type 2 diabetes.

Sleep apnea can be greatly eased by wearing a CPAP mask at night to assist with breathing. A good night’s rest has health benefits, including reducing the risk of diabetes.

Should pregnant women be aware of sleep apnea?

Yes. A study conducted in 2013 of 1,673 women discovered that sleep apnea was linked to emergency C-sections or babies with low birth weight. The researchers believe that because sleep apnea is linked to heavier people, the weight gain during pregnancy may increase the risk for sleep apnea. Some of the symptoms of sleep apnea-snoring, moodiness, excessive daytime sleepiness, trouble staying alert during the day-are also thought to be standard side effects of pregnancy. But if a pregnant woman knows that she has many of these symptoms, she may want to discuss the possibility that some may be caused by sleep apnea (and learn some possible remedies) with her doctor.

Is there a connection between gestational diabetes and sleep apnea?

Yes, some studies indicate that sleep apnea may be more common than previously believed in women with gestational diabetes. (For more about gestational diabetes, see the chapter “Other Types of Diabetes.”) One study in particular looked at a group of pregnant Asian women who were obese and had gestational diabetes. The researchers found that the majority of women in this group also had sleep apnea, which also caused their blood glucose levels to rise. The study did not determine causality-whether the sleep apnea led to the high blood sugar or high blood glucose levels led to the sleep apnea-but other studies seem to indicate that gestational diabetes is associated with the increased risk for obstructive sleep apnea.


Is diabetes caused by smoking?

No, there is no evidence that smoking causes diabetes, but smoking can aggravate health conditions associated with diabetes. In fact, tobacco use-from cigarettes to cigars-increases the risk of developing type 2 diabetes and even makes managing the condition much harder if a person develops the disease.

What recent research indicated a connection between seniors who smoke and diabetes?

In a study conducted in Germany, the data showed that seniors who smoked were almost three times more likely to develop type 2 diabetes than those who never smoked. (In this study, seniors were people age 60 or over.) If a senior also had prediabetes and was a smoker, the number rose to eight times more likely to end up with type 2 diabetes.

Recent studies indicate that smokers have a greatly increased risk of diabetes than nonsmokers.

What are some health problems associated with smoking that are exacerbated by diabetes-and vice versa?

Although diabetes is not caused by smoking, the disease can exacerbate some conditions associated with smoking. The Canadian Diabetes Association says recent studies indicate that smoking is an independent risk factor for type 2 diabetes-with those who smoke 25 or more cigarettes a day having double the diabetes risk than nonsmokers. Diabetes can cause damage to a person’s heart and larger blood vessels, and smoking compounds the risk of this damage. Smoking is also thought to contribute to hardening of the arteries, which, when combined with high blood glucose levels from diabetes, can accelerate the development of diabetic complications. Thus, it is estimated that a person with diabetes who also smokes has about three times the risk of a heart attack compared to someone who does not smoke.

There are other problems with diabetes and smoking. Smokers who have diabetes can also have higher risks for serious health complications, such as kidney disease, retinopathy (eye disease that can cause blindness), and peripheral neuropathy (damaged nerves in the arms and legs that cause weakness, numbness, pain, and sometimes poor coordination). In addition, smoking by a person with diabetes increases the chances of stroke, faster nerve damage, and poor blood flow, especially in the extremities (hands and feet). If there is poor blood flow in the legs and feet because of smoking and diabetes, it can lead to infections and ulcers that are often difficult to treat. And in terms of blood vessels and nerve damage in the extremities, there is added incentive to quit smoking if a person has diabetes: It is estimated that some 90 percent of people with diabetes who have a foot amputated are smokers.

Is it true that diabetes can be harder to control after a person stops smoking?

Not necessarily. Some researchers believe that after a smoker quits smoking, he or she gains weight and finds diabetes control more difficult, especially if the person doesn’t exercise and eat a healthy diet. But other research suggests that smoking, while it does lower the body mass index (BMI; for more about BMI, see chapter “Diabetes and Obesity”), may actually redistribute a person’s body weight into a pattern that can lead to obesity, which in turn can lead to diabetes. Thus, most health care professionals advise patients that smoking does increase the risk of diabetes (and often other diseases), making cessation of smoking that much more advantageous to a person’s present and future health.

How much of an increased risk for type 2 diabetes is there for smokers?

According to a 2015 study published in the Lancet Diabetes & Endocrinology, compared with people who have never smoked, people who smoke have a 37 percent increased risk for type 2 diabetes. For people who formerly smoked, the number decreased to a 14 percent increased risk for type 2 diabetes. The researchers even broke down the amount a person smokes and diabetes risk: Compared with a person who never smoked, a light smoker had a 21 percent increased risk of type 2 diabetes, a moderate smoker a 34 percent increased risk, and heavy smokers a 57 percent increased risk. The research also indicated that a smoker who has either type 1 or type 2 diabetes increased the relative risk of total mortality and cardiovascular events (such as heart attacks and strokes) by about 50 percent.

Can secondhand smoke affect a person with diabetes?

Yes, according to some studies, if a person with diabetes is exposed to secondhand smoke (in most cases, if a nonsmoker lives with a smoker), it does have an effect on the disease. In 2015, a mega-analysis of 88 studies (which included a total of around 6 million people) found that people exposed to secondhand smoke have a significantly increased risk of developing type 2 diabetes. According to the data, compared with people who never smoked, inhaling secondhand smoke raised the risk of type 2 diabetes by 22 percent. Thus, the researchers pointed out that past studies of passive smoking’s effect on health showed an increased risk of cardiovascular disease and cancer (mostly lung)-and also the risk of developing type 2 diabetes.

If a person with diabetes quits smoking, how does it affect his or her overall health?

There is good news if a person with diabetes (or even without the disease) quits smoking. According to Harvard Medical School, some of the health benefits occur right away, especially a better stabilization of a person’s glucose levels. In addition, researchers have found that a person with diabetes who quits smoking will notice that insulin resistance begins to decrease as soon as eight weeks after that last cigarette.


What is a common definition of cancer?

Cancer is caused by the unrestrained growth of cells in the body. Cells that do not “follow the rules” of the normal cell life cycle may eventually become cancerous. This means that the cells reproduce more often than normal, creating cellular overgrowth commonly referred to as tumors. Usually this happens over an extended period of time and begins with changes at the molecular level. There are more than 100 distinct types of cancer, each of which behaves in a specific fashion and responds to treatments differently.

What types of cancer are associated with diabetes?

Diabetes is often associated with several types of cancer, including a higher risk of developing pancreatic, hepatic (liver), endometrial (ovaries), breast, lung, bladder, and colorectal cancers. These cancers are all independently associated with insulin resistance and also hyperinsulinemia. The reason for this connection between so many cancers and diabetes is still being explored, but there are a few possible explanations. For example, according to Harvard Medical School, cancer and diabetes share several risk factors, including obesity, aging, and a sedentary lifestyle, along with a diet high in fat and refined carbohydrates. Another connection is that the changes in the body associated with diabetes, including insulin resistance, high blood glucose levels, and inflammation, may also help contribute to the risk of developing cancers. This is why most health care professionals suggest that a person with diabetes stick to a healthful lifestyle and schedule routine cancer screenings.

Are there any treatments for diabetes that may lower the risk of cancer?

Yes, but some also may raise the risk. Metformin is often cited as reducing the risk of many types of cancer, and a class of oral medications called thiazolidinediones (for example, pioglitazone) have been noted to lower the risk of some cancers, while increasing the risk of others (often cited is bladder cancer and even other medical problems such as an increased risk of heart failure). In addition, GLP-1 therapies (or glucagon-like peptide 1 receptor agonists, which are often mentioned as a treatment for type 2 diabetes) have often been connected to an increased risk of pancreatic and thyroid cancers. But as usual, many of these connections have not been proven by extensive research.

Having a sedentary lifestyle puts you at greater risk of not only diabetes but also some types of cancer.

Does any type of cancer cause diabetes?

No, no research has found that any type of cancer causes diabetes, although, as seen above, diabetes is often associated with a higher risk of several cancers. This lack of association makes sense, as both diseases develop for different reasons.


What is an allergic reaction?

An allergic reaction is a response to a substance that is often harmless to most other people. Allergens, the antigens (chemical substances, mostly in the form of proteins) that can cause an allergic reaction, are found in many foods and medications, along with responses to various plants, animals, chemicals, dust, or molds. The more common allergic reactions are allergic rhinitis (hay fever), allergic conjunctivitis (an eye reaction), asthma, atopic dermatitis (skin reactions), urticaria (hives), and what are called severe systemic allergic reactions (such as anaphylaxis).

Do allergies cause diabetes?

No, there is no evidence that any allergies cause diabetes (although there have been some rare reports of allergies to insulin in people with type 2 diabetes). But that does not mean people with diabetes don’t have allergies (such as allergies to certain foods and medications).

How can certain medications for allergies affect a person with type 2 diabetes?

Several over-the-counter (OTC) and prescription allergy medications can affect a person with type 2 diabetes. For example, certain medicines, especially OTC decongestants taken orally, can constrict blood vessels in the body and cause such effects as a rise in blood glucose. During allergy season, taking cough drops that are not sugar-free can often cause a rise in glucose levels. Some prescription nasal sprays for a stuffy nose may contain steroids, which can stimulate the liver to produce more glucose-raising blood glucose levels.

What is anaphylactic shock?

Anaphylactic shock, or anaphylaxis, is a severe allergic reaction to certain allergens, usually within minutes after exposure. For example, many people who are severely allergic to the venom in bee stings can experience anaphylactic shock. Anaphylactic reactions usually involve one or several organs in the body, such as the skin (often as a rash), respiratory system (usually as breathing difficulties), and gastrointestinal tract (most often as vomiting and/or diarrhea).

Many people who may suffer severe reactions to bee stings or snake bites carry what is called an Epipen™ with them, a needle-and-syringe medical device that provides a premeasured, single dose of epinephrine. When delivered soon after exposure to the allergen, this self-delivered injection usually helps to stave off a potentially life-threatening reaction.

What drug causes the most allergic reactions?

Penicillin is a common cause of drug allergy. One research study found that approximately 7 percent of normal volunteers react to penicillin-allergy skin tests (IgE antibodies). Anaphylactic reactions to penicillin occur in 32 of every 100,000 exposed patients.

What allergies can a person develop?

There are a large number of allergens that can affect humans and cause allergies. The most common allergens are dust and mites. People can also be allergic to various foods, pollen, chemicals in cosmetics, medications, fungal spores, insect venom, various microorganisms-even a person’s own body cells can develop abnormally, causing an allergic reaction. If a person is sensitive to one of these allergens, allergies can develop. In people who are not sensitive, there will be no response.

Can some allergy medications affect a person’s diabetes?

Yes. Most people take allergy medications if they have reactions to tree, grass, and weed pollen, especially in the spring. Many of the allergy medications-for example, from the prescription name-brand Flonase to the over-the-counter Nasacort-contain corticosteroids. These drugs reduce the inflammation caused by seasonal allergies but can also cause a rise in blood glucose levels. Because of this, most health care professionals recommend that seasonal allergy-prone diabetics pay closer attention to their blood glucose levels. They may also want to discuss modifying their diabetes medicine or insulin with their health care provider or see whether there is another allergy medicine that does not contain corticosteroids.