Diabetes mellitus is a chronic condition associated with abnormally high levels of sugar (glucose) in the blood. People with diabetes either do not produce enough insulin—a hormone that is needed to convert sugar, starches and other food into energy needed for daily life—or cannot use the insulin that their bodies produce. As a result, glucose builds up in the bloodstream. If left untreated, diabetes can lead to blindness, kidney disease, nerve disease, heart disease, and stroke.
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), 15.7 million Americans—nearly 6% of the population—have diabetes.
Although an estimated 10.3 million have been diagnosed, 5.4 million people are not aware that they have the disease. It is the seventh leading cause of death in the United States and it affects males and females of all ages, races, and income levels.
There are two major types of diabetes mellitus:
- Type 1—Also known as insulin-dependent diabetes mellitus (IDDM), type 1 diabetes is an autoimmune disease (a condition arising from and directed against a person’s own tissues) in which the pancreas produces little or no insulin. Individuals with type 1 diabetes must take insulin throughout their lives to manage their condition. Type 1 diabetes usually occurs most often in children and young adults and it accounts for 5% to 10% of all diabetes cases.
- Type 2—The most common form of diabetes (accounting for 90% of all cases), type 2 diabetes is a metabolic disorder resulting from the body’s inability to make enough, or properly use, insulin. It occurs most frequently in people who are overweight, inactive, and older than 40 years of age (although the rates in children are rising). Most people with type 2 diabetes—about 60% to 70%—do not need to take insulin to manage their condition, however. For this reason, type 2 diabetes is also called noninsulin-dependent diabetes mellitus (NIDDM).
Gestational diabetes is a type of diabetes that can develop when a woman is pregnant. Towards the end of a pregnancy (usually the third trimester), a woman may have higher than normal levels of glucose in her bloodstream. One percent of all pregnant women develop gestational diabetes. Although it usually disappears after delivery, the mother is at increased risk of developing type 2 diabetes later in life. Other types of diabetes are associated with genetic syndromes, surgery, drugs, malnutrition, infections, and other illnesses.
Signs and Symptoms
While production of insulin diminishes gradually over a matter of years, the signs and symptoms of type 1 diabetes tend to appear abruptly, once 80% to 90% of the pancreatic cells can no longer make insulin. The signs and symptoms include:
- Excessive urination
- Excessive intake of water and/or food
- Loss of bladder control in children after they had already been trained
- Unintended weight loss over several days (people with type 1 diabetes tend to be thin)
- High levels of glucose in the blood and urine
- Nausea and vomiting
- Abdominal pain or discomfort
- Weakness and excessive fatigue
- Increased susceptibility to infection, such as vaginitis and other yeast infections
- Blurred vision
- Irritability, restlessness, and/or apathy
- Ketoacidosis —a potentially fatal condition marked by an accumulation of ketones (chemicals that build up in the bloodstream when the body is forced to burn fat instead of glucose) and increased acidity of the blood
People with type 2 diabetes often have no symptoms, and their condition is detected only when a routine exam reveals high blood glucose levels. Occasionally, however, a person with type 2 diabetes may experience symptoms listed below, which tend to appear slowly over time:
- Numbness or burning sensation of the feet, ankles, and legs
- Blurred or poor vision
- Poor wound healing
In some cases, symptoms may mimic type 1 diabetes and appear more abruptly:
- Excessive urination and thirst
- Yeast infections
- Whole body itching
- Coma—in severe cases, high blood glucose may affect water distribution in brain cells, causing a state of deep unconsciousness, or coma.
Both types of diabetes are caused by the absence, insufficient production, or lack of response by cells in the body to the hormone insulin. Insulin is a key regulator of the body’s metabolism. After meals, food is digested in the stomach and intestines. Sugar (glucose) molecules are absorbed directly into the bloodstream, and blood glucose levels rise. Under normal circumstances, the rise in blood glucose levels signals specific cells in the pancreas—called beta cells—to secrete insulin into the bloodstream. Insulin, in turn, enables glucose to enter cells in the body to be burned for energy or stored for future use.
People with type 1 diabetes produce little or no insulin at all because their immune systems attack and destroy the insulin-producing beta cells in the pancreas. Although it is not clear what specifically causes type 1 diabetes, it is believed that exposure to a toxin or viral infection may trigger this autoimmune attack in genetically susceptible individuals. In type 1 diabetes, beta cells are destroyed gradually, but symptoms do not appear until at least 80% of the cells are affected.
Type 2 diabetes usually develops in older, overweight individuals who become resistant to the effects of insulin over time. When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin but, for unknown reasons, the body cannot use the insulin effectively (a condition called insulin resistance). In people with type 2 diabetes, production of insulin by the pancreas also tends to diminish.
As mentioned above, other types of diabetes can occur as a result of pregnancy (gestational diabetes), genetic disorders, surgery, medications such as steroids, malnutrition, infections, and other illnesses. In addition, physical stress can cause a temporary rise in blood sugar or even uncover “hidden” diabetes.
- Family history of type 1 diabetes
- Mother who had preeclampsia (a condition characterized by a sharp increase in blood pressure during the third trimester of pregnancy)
- Family history of autoimmune diseases, including Hashimoto’s thyroiditis, Graves’ disease, myasthenia gravis, Addison’s disease, or pernicious anemia
- Viral infections during infancy including mumps, rubella, and coxsackie
- Child of an older mother
- Northern European or Mediterranean descent
- Consumption of cow’s milk during infancy (this idea is controversial however)
- Family history of type 2 diabetes (one-quarter to one-third of all individuals with type 2 diabetes have a family history of the condition)
- Age older than 40 years
- Excess body fat, particularly around the waist
- Sedentary lifestyle and high-fat, high-calorie diet
- Abnormal levels of cholesterol and/or trigylcerides in the blood
- High blood pressure
- History of gestational diabetes or polycystic ovary syndrome (a hormonal disorder that causes women to have irregular or no menstruation)
- African American, Hispanic American or Native American (particularly Pima tribe in Arizona) descent
- Low birth weight and/or a mother’s malnutrition in pregnancy may cause metabolic disturbances in a fetus that lead to diabetes later in the child’s life
According to the American Diabetes Association, all pregnant women should be screened for gestational diabetes during their third trimester and people who are 45 years or older should have their blood glucose levels checked randomly every 3 years. Those who have a high risk of developing diabetes (such as people with a family history of the disease) should be tested more often.
When a healthcare practitioner suspects that an individual may have diabetes, he or she will draw blood samples and send them to a laboratory for analysis. Different types of tests are used to diagnose diabetes—random plasma glucose, fasting plasma glucose, and oral glucose tolerance tests. If the blood sugar is elevated (as detected by a random measurement in the middle of the day), a fasting plasma glucose test will likely be ordered. This means that, after an individual has fasted overnight (at least 8 hours), a sample of blood is drawn and sent to the laboratory for analysis. Normal fasting plasma glucose levels are less than 110 milligrams per deciliter (mg/dL). People with fasting plasma glucose levels of more than 140 mg/dL (on two or more tests on different days) definitely have diabetes. If results from the fasting plasma glucose test are questionable (meaning glucose levels are between 120 and 140 mg/dL) and diabetes is still suspected, a glucose tolerance test will be ordered. In this test, three measurements of blood glucose are taken over 2 hours after a large amount of sugar is ingested. If two of the measurements (or more) are at least 200 mg/dL, diabetes is diagnosed.
Once a diagnosis of type 2 diabetes is made, several follow-up visits are necessary to establish appropriate medication dosages. In type 1 diabetes, insulin is generally started in the hospital, followed by precise adjustments at home (often with the aid of a visiting nurse). People with type 1 diabetes and many of those with type 2 diabetes are taught how to self-monitor their blood sugars. The doctor is likely to request physical exams every 3 to 6 months, where he or she will evaluate for signs of blood vessel, nervous system, eye, and kidney disorders. Blood and urine tests are generally performed as part of these follow-up appointments. Dieticians are also an integral part of care from the outset and during follow-up visits.
Although possible methods for preventing type 1 diabetes are under investigation, there is currently no proven way to prevent this type of diabetes. Interestingly, though, a recent study conducted in Finland suggests that adequate amounts of vitamin D, particularly in the first year of life, may decrease one’s chances of developing type 1 diabetes within the first 30 years of life. In northern Finland (where the annual exposure to sunlight is very limited) more than 10,000 infants were followed for up to 30 years. Those given at least 2,000 IU of vitamin D per day (generally from cod liver oil) for the first year of life were significantly less likely to develop type 1 diabetes over a 30-year time course than infants who were given less than that.
Considerable evidence from population-based studies suggests that type 2 diabetes is highly preventable—particularly through exercise and weight management. Individuals who are physically inactive and/or overweight are much more likely to develop type 2 diabetes. Similarly, people who move from a non-Westernized country to a Westernized country (such as the United States where individuals tend to be overweight and live sedentary lives), increase their risk for type 2 diabetes considerably. Studies suggest that vigorous physical activity is not necessary in order to protect against the development of diabetes; moderate, regular exercise such as walking for 30 minutes most days of the week, is enough. In general, lifestyle interventions used to treat diabetes may help prevent the condition as well.
The goal of diabetes treatment is to achieve and maintain blood glucose levels within or near the normal range (90 to 126 milligrams per deciliter [mg/dL]). A recent major study, called the Diabetes Control and Complications Trial (DCCT), found that diabetics who kept their blood glucose levels close to normal reduced their risk of developing major complications from the condition. Maintaining blood glucose levels is often very difficult, however. People with diabetes must learn how to manage their condition on a daily basis to prevent blood glucose levels from dropping too low (hypoglycemia) or spiking too high (hyperglycemia). Treatment for type 1 diabetes requires a strict regimen that typically includes a carefully calculated diet, planned exercise, daily blood glucose testing at home (even several times per day), and, most importantly, multiple daily insulin injections. Similarly, healthy eating habits, physical activity, and daily blood glucose testing are the basic tools that people with type 2 diabetes need to manage their condition. Some people with type 2 diabetes (30% to 40%) also require insulin injections.
In summary, people with diabetes should use the following therapies to help manage their blood glucose levels and to prevent complications associated with the condition:
- Lifestyle changes, particularly in diet and exercise habits
- Medications, particularly insulin for individuals with type 1 diabetes and some people with type 2 diabetes
- Supplements, including fiber and chromium
- Relaxation techniques
- Acupuncture for pain from nerve damage
People with diabetes can improve significantly from lifestyle changes—particularly diet and exercise. Type 2 diabetics can even eliminate the need for medications when they make adequate and appropriate lifestyle changes.
The American Diabetes Association (ADA) recommends that individuals with diabetes consume a healthy, low-fat diet, rich in grains, fruits, and vegetables. A healthy diet typically includes 10% to 20% of daily calories from protein (including poultry, fish, dairy, and vegetable sources). Diabetics who also have kidney disease should work with their healthcare practitioners to limit protein intake to 10% of daily calories. A low-fat diet typically includes 30% or less of daily calories from fat—less than 10% from saturated fats and up to 10% from polyunsaturated fats (such as fats from fish). In addition, weight loss should be part of the plan for those with type 2 diabetes. Moderate weight loss (achieved by reducing calories by 250 to 500 per day and exercising regularly) not only controls blood sugars but blood pressure and cholesterol as well. Diabetics who eat healthy, well-balanced diets will not need to take extra vitamins or minerals to treat their condition.
Exercise plays an important role in controlling diabetes because it lowers blood sugar and helps insulin to work more efficiently in the body. Exercise also enhances cardiovascular fitness by improving blood flow and increasing the heart’s pumping power. It also promotes weight loss and lowers blood pressure. Exercise only has value, however, when it is done regularly—at least three to four sessions per week for 30 to 60 minutes per session. People with type 2 diabetes who exercise regularly have been shown to lose weight and gain better control over their blood pressure, thereby reducing their risk for cardiovascular disease (a major complication of diabetes). Studies have also shown that people with type 1 diabetes who regularly exercise reduce their need for insulin injections.
Despite the benefits of exercise, however, many people have difficulty sticking with an exercise program for a long period of time. Healthcare practitioners can help develop suitable routines as well as strategies that may improve adherence to such routines. Anyone with long-standing diabetes should undergo a thorough screening before beginning an exercise program and should be monitored carefully by his or her physician.
Medications for diabetes must always be used in conjunction with lifestyle changes, particularly diet and exercise, to improve the symptoms of diabetes.
Plant-based medicines have long been used in the treatment of diabetes. For instance, the plant extract guanidine, which lowers blood glucose, prompted the development and use of biguanides, a commonly used oral medication for diabetes. Other herbs may have a role in the management or prevention of diabetes. These include:
Aloe (Aloe vera)
Studies suggest that aloe vera taken orally might help reduce blood glucose in individuals who have type 2 diabetes. In a few studies, diabetic women who received aloe vera juice experienced significant reductions in blood glucose levels compared to women who received placebo. Although further studies are need to determine the safety and effectiveness of aloe in the treatment of diabetes, it seems possible that the herb may prove to be a useful addition to the diet, exercise, and medication program for type 2 diabetics.
Fenugreek seeds (Trigonella foenum graecum)
Fenugreek seeds, a spice found in many curry preparations, are high in fiber and have been shown to regulate glucose and improve lipid levels in both animals and humans. In two small studies of individuals with either type 1 or type 2 diabetes, fenugreek seed powder lowered blood glucose and improved levels of blood cholesterol and trigylcerides, among other beneficial effects.
American ginseng (Panax quinquefolium)
Although both Asian (Panax ginseng) and American (Panax quinquefolium) appear to lower blood glucose levels, only American ginseng has been studied in scientific trials. One study found that people with type 2 diabetes who take American ginseng before or together with a glucose meal experience a reduction in glucose levels after they consume the meal.
Numerous other herbs have been used traditionally to regulate glucose levels in the body. Although preliminary research is promising, more research is needed to determine whether the following herbs are safe and effective for the treatment of diabetes:
- Onion (Allium cepa)
- Garlic (Allium sativum)
- Andrographis (Andrographis paniculata)
- Green tea (Camellia sinensis)
- Indian cluster bean (Cyamopsis tetgonolobus)
- Gurmar (Gymnema sylvestre)
- Bitter melon or karela (Momordica charantia)
- Tinospora gulancha (Tinospora cordifolia)
- Bilberry (Vaccinium myrtillus)
Some researchers speculate that acupuncture may trigger the release of natural painkillers and reduce the debilitating symptoms of a complication of diabetes known as neuropathy (nerve damage). In one study of diabetics suffering from chronic, painful neuropathy, acupuncture reduced pain and improved sleep in 77% of the participants and eliminated the need for pain medications in 32% of the participants. Given these findings, acupuncture may be a reasonable option for diabetics with neuropathy who either find no symptom relief or develop side effects from conventional drug treatment.
Stressful life events can worsen diabetes in several ways. For example, stress stimulates the nervous and endocrine systems in ways that increase blood glucose levels and disrupts healthful behaviors (increasing the chances that an individual may consume a high level of calories and limit his or her physical activity—a pattern that leads to elevated blood glucose).
It makes sense, then, to consider stress management as part of the treatment and prevention of diabetes. Studies have shown that diabetics who participate in biofeedback sessions (a technique that increases awareness of and control of the body’s response to stress) are more likely to reach target blood glucose levels than diabetics who do not receive biofeedback. Although other studies have produced results that contradict this, researchers and clinicians generally agree that long-term stress is likely to worsen diabetes and that biofeedback, tai chi, yoga, and other forms of relaxation may help motivate people with diabetes to change their habits in order to manage their condition.
Diabetic women of child-bearing age should consult an endocrine specialist about the benefits of managing glucose levels before trying to conceive.
Approximately 7% of all pregnant women in the United States are diagnosed as having gestational diabetes. Risk factors for developing diabetes while pregnant include:
- Modest weight gain prior to pregnancy (11 to 22 pounds or more)
- Family history of diabetes
- Tobacco use
- African, Hispanic-American, or Asian ancestry
- Age older than 50 at conception
Normalizing glucose levels in women with gestational diabetes reduces their risk of complications, such as having an overweight baby, birth trauma, or the need for cesarean section. If the mother’s glucose levels are uncontrolled, an infant can be stillborn or suffer from any of a number of complications, including defects of the brain or central nervous system, an abnormally large body or organs, heart or kidney abnormalities, asphyxia, respiratory distress, and congestive heart failure.
If dietary restrictions fail to improve glucose levels, a woman with gestational diabetes may need insulin. Oral diabetes medications should not be used during pregnancy. Women who develop gestational diabetes may experience the condition again in subsequent pregnancies. Gestational diabetes also increases the risk for developing type 2 diabetes.
Prognosis and Complications
People who maintain tight control over their blood glucose levels can prevent or delay the development of long-term complications from diabetes. Generally, type 1 diabetes is associated with more complications than type 2 diabetes.
Long-term complications of diabetes may include:
- Heart disease and stroke
- Vision loss and blindness
- Kidney disease
- Neuropathy (nerve damage)
- Foot ulcers and infections
- Skin problems, including bruising, dryness, itching, hair loss, warts, gangrene (tissue death), and skin ulcers
According to the National Institute of Diabetes and Digestive and Kidney Diseases, 798,000 Americans are diagnosed with diabetes each year. Before the discovery of insulin in 1921, most people with diabetes (particularly those with type 1 diabetes) died soon after they were diagnosed. Although insulin is not a cure for diabetes, its discovery was the first major breakthrough in diabetes treatment. Today, it is also understood that for people with diabetes, healthy eating and exercise habits, daily glucose monitoring, and appropriate medication are key elements for a long, healthy life.