Diabetes Demands a Triad of Treatments
by Paula Kurtzweil & Audrey Hingley
Actress Mary Tyler Moore battles it. Country singer Mark Collie has it. Rhythm and blues singer Patti LaBelle was diagnosed with it recently.
Celebrities like Moore, Collie and LaBelle are just three well-known faces amid the 16 million Americans suffering from diabetes mellitus, a chronic disease in which the pancreas produces too little or no insulin, impairing the body's ability to turn sugar into usable energy.
In recent years, the Food and Drug Administration has taken steps that make it possible for people with diabetes to maintain better control of their disease. In the early 1990s, the agency, along with the U.S. Department of Agriculture, put in place food labeling regulations that, among other things, require labels of most packaged foods to provide nutrition information. So, people with diabetes can now learn about the nutritional content of almost all the foods they eat.
More recently, FDA has approved a fast-acting form of human insulin and several new oral diabetes drugs, including Glucophage (metformin), Avandia (rosiglitazone) and Actos (pioglitazone), drugs that improve sensitivity to insulin. These drugs are designed to help Type II diabetics make better use of the insulin produced by their bodies.
While it is treatable, diabetes is still a killer. The seventh leading cause of death in America, diabetes claims an estimated 80,000 lives each year.
Philip Cryer, M.D., a professor at Washington University School of Medicine in St. Louis and past president of the American Diabetes Association, believes that most people simply don't understand the magnitude of the diabetes problem. "Diabetes is an increasingly common, potentially devastating, treatable yet incurable, lifelong disease. It's the leading cause of blindness in working-age adults, the most common cause of kidney failure leading to dialysis or transplants, and is a leading cause of amputation," he says. "The most recent estimate we have of diabetes' cost [in terms of] direct medical care is [more than] $90 billion dollars annually--more than heart disease, cancer, or AIDS."
But, the increasing emphasis on the importance of a healthy diet, the availability of glucose monitoring devices that can help diabetics keep a close watch over blood sugar levels, and the wide range of drug treatments enable most diabetics to live a near-normal life.
Two Types of Diabetes
There are two main types of diabetes, Type 1 and Type 2. Insulin-dependent, or Type 1, diabetes affects about 5 percent of all diabetics. It's also known as juvenile diabetes because it often occurs in people under 35 and commonly appears in children or adolescents. For example, Mary Tyler Moore, a Type 1 diabetic who is international chairman of the Juvenile Diabetes Foundation, was diagnosed in her late 20s, following a miscarriage. A routine test found her blood sugar level was 750 milligrams per deciliter (mg/dl), as compared with the normal level, 70 mg/dl to 105 mg/dl. And Collie has been diabetic since age 17.
In Type 1 diabetes, the insulin-secreting cells of the pancreas are destroyed, with insulin production almost ceasing.
Type 1 diabetics must inject insulin regularly under the skin. Insulin cannot be taken by mouth because it cannot be absorbed from the gastrointestinal tract into the bloodstream. Doses range from one or two up to five injections a day, adjusted in response to regular blood sugar monitoring. Insulin regulates both blood sugar and the speed at which sugar moves into cells.
Symptoms of untreated insulin-dependent diabetes include:
- continuous need to urinate
- excessive thirst
- increased appetite
- urinary tract infections
- recurrent skin infections, such as boils
- vaginal yeast infections in women
- blurred vision
- tingling or numbness in hands or feet.
If Type 1 diabetes goes untreated, a life-threatening condition called ketoacidosis can quickly develop. If this condition is not treated, coma and death will follow.
Type 2, or non-insulin-dependent, diabetes is the most common type. It results when the body produces insufficient insulin to meet the body's needs, or when the cells of the body have become resistant to insulin's effect. While all Type 1 diabetics develop symptoms, only a third of those who have Type 2 diabetes develop symptoms. Many people suffer from a mild form of the disease and are unaware of it. Often it's diagnosed only after complications are detected.
When they occur, Type 2 symptoms may include frequent urination, excessive thirst, fatigue, an increase in infections, blurred vision, tingling in hands or feet, impotence in men, and absence of menstrual periods in women.
Type 2 diabetes usually develops in people over 40, and it often runs in families. For instance, Patti LaBelle was diagnosed with Type 2 diabetes at age 50; her mother died of the disease.
Type 2 diabetes is often linked to obesity and inactivity and can often be controlled with diet and exercise alone. Type 2 diabetics sometimes use insulin, but usually oral medications are prescribed if diet and exercise alone do not control the disease.
Malfunction in Glucose Metabolism
In a normal body, carbohydrates (sugars and starches) are broken down in the intestines to simple sugars (mostly glucose), which then circulate in the blood, entering cells, where they are used to produce energy. Diabetics respond inappropriately to carbohydrate metabolism, and glucose can't enter the cells normally.
Insulin--a hormone that is made in the pancreas and released into the bloodstream and carried throughout the body--enables the organs to take sugar from the blood and use it for energy. If body cells become resistant to insulin's effect or if there isn't enough insulin, sugar stays in the blood and accumulates, causing high blood sugar. At the same time, cells starve because there's no insulin to help move sugar into the cells.
Diabetes is diagnosed by measuring blood sugar levels. This can begin with a urine test sampled for glucose because excess sugar in the blood spills over into the urine. Further testing involves taking blood samples after an overnight fast. Normal fasting blood glucose levels are between 70 mg/dl and 105 mg/dl; a fasting blood glucose measurement greater than 126 mg/dl on two separate occasions indicates diabetes.
Diabetes can result in many complications, including nerve damage, foot and leg ulcers, and eye problems that can lead to blindness. Diabetics also are at greater risk for heart disease, stroke, narrowing of the arteries, and kidney failure. But evidence shows that the better the patient controls his or her blood sugar levels, the greater the chances that the disease's serious complications can be reduced.
Diet for Diabetes
Because food intake affects the cells' need for insulin and insulin's ability to lower blood sugar, diet is the cornerstone of diabetes treatment.
Today, diabetes experts no longer recommend a single diet for all people with diabetes. Instead, they advocate dietary regimes that are flexible and take into account a person's lifestyle and particular health needs.
The American Diabetes Association (ADA) described some common options in a 1994 position paper. A first step, for example, is to encourage people with diabetes to follow the government's Dietary Guidelines for Americans and Food Guide Pyramid.
According to Phyllis Barrier, a registered dietitian and director of program publications for ADA, this step alone may be enough to maintain normal blood glucose, or sugar, levels. Maintaining these levels helps reduce the risks of retinopathy and other diabetes-related complications, such as kidney and heart disease.
Other people use the Exchange Lists for Meal Planning, she said. This system, established by the American Dietetic and American Diabetes associations, separates foods into six categories based on their nutritional makeup. People following this plan choose a set amount of servings from each category daily, depending on their nutritional needs.
A more sophisticated method of meal planning is "carbohydrate counting," in which grams of carbohydrate consumed are monitored and adjusted daily according to blood glucose levels. Some people count protein and fat grams, too. These two nutrients also can affect blood sugar levels, although to a lesser extent.
Whatever method used, ADA recommends these general dietary guidelines for people with diabetes:
- Limit fat to 30 percent or less of daily calories.
- Limit saturated fat to 10 percent or less of daily calories.
- Limit protein to 10 to 20 percent of daily calories. For those with initial signs of diabetes-induced kidney disease, restrict protein to 10 percent of daily calories.
- Limit cholesterol to 300 milligrams or less daily.
- Consume about 20 to 35 grams of fiber daily.
Most of these guidelines are a good idea for the general population, as well.
Those who are overweight also may m oderately restrict calories. ADA recommends a calorie reduction of 250 to 500 calories less than normally eaten per day. That should result in a weight loss of about 0.2 to 0.5 kilograms (one-half to 1 pound) a week, ADA's Barrier said. The calorie restriction, along with increased exercise, should help an overweight person achieve a weight loss of 5 to 10 kilograms (11 to 22 pounds) in about six months to one year. The weight loss, although moderate, can help improve diabetes control.
Carbohydrate intake can vary, but, contrary to popular belief, the type of carbohydrate is not a factor. As ADA points out in its position paper, people with diabetes have for years been told to avoid "simple" sugars, such as table sugar and those found in sugary snacks, because they were thought to elevate blood glucose more quickly and more severely than other carbohydrates.
"There is, however, very little scientific evidence that supports this assumption," ADA wrote in its position paper. The organization recommended that the focus be on total carbohydrate--not source of carbohydrate. If sugar and sugar-containing foods are eaten, the amounts must be figured into the daily allotment of carbohydrate.
Get the Nutrition Facts
Considering these factors, how should people with diabetes go about using the food label?
They can begin with the Nutrition Facts panel, usually on the side or back of the package.
Serving sizes now are more uniform among similar products and reflect the amounts people actually eat. The similarity makes it easier to compare the nutritional qualities of related foods.
People who use the Exchange Lists should be aware that the serving size on the label may not be the same as that in the Exchange Lists. For example, the label serving size for orange juice is 8 fluid ounces (240 milliliters). In the exchange lists, the serving size is 4 ounces (one-half cup) or 120 mL. So, a person who drinks one cup of orange juice has used two fruit exchanges.
The label also gives grams of total carbohydrate, protein and fat, which can be used for carbohydrate counting.
The values listed for total carbohydrate include all carbohydrate, including dietary fiber and sugars listed below it. Not singled out is complex carbohydrates, such as starches.
The sugars include naturally present sugars, such as lactose in milk and fructose in fruits, and those added to the food, such as table sugar, corn syrup, and dextrose.
The listing of grams of protein also is helpful for those restricting their protein intake, either to reduce their risk of kidney disease or to manage the kidney disease they have developed.
Front Label Info
Elsewhere on the label, consumers may find claims about the food's nutritional benefits. These claims signal that the food contains desirable levels of certain nutrients.
Some claims, such as "low fat," "no saturated fat," and "high fiber," describe nutrient levels. Some of these are particularly interesting to people with diabetes because they highlight foods containing nutrients at beneficial levels.
Other claims, called health claims, show a relationship between a nutrient or food and a disease or health condition. FDA has authorized eight such claims; they are the only ones about which there is significant scientific agreement. [Note: Since this article was published, several more claims have been approved. For the most recent listing of such claims, see "A Food Labeling Guide--Appendix C" on FDA's Center for Food Safety and Applied Nutrition Website.]
Three that relate to heart disease are of particular interest to people with diabetes:
- A diet low in saturated fat and cholesterol may help reduce the risk of coronary heart disease.
- A diet rich in fruits, vegetables and grain products that contain fiber, particularly soluble fiber, and are low in saturated fat and cholesterol may help reduce the risk of coronary heart disease.
- Soluble fiber from whole oats, as part of a diet low in saturated fat and cholesterol, may help reduce the risk of coronary heart disease.
Nutrient and health claims can be used only under certain circumstances, such as when the food contains appropriate levels of the stated nutrients.
Shot of Insulin
Taking regular injections of insulin is a must for some diabetics.
The first insulin marketed for diabetes was derived from the pancreas of cows and pigs. Today, chemically synthesized human insulin is the most often used. It is prepared from bacteria with DNA technology. Human insulin is not a great advantage over animal insulin, and most doctors don't recommend that patients on animal insulin automatically switch to human insulin. But if they do switch, dosages may change. Human insulin is preferred for those patients who take insulin intermittently.
Diabetics on intensified insulin therapy--that is, those needing multiple daily injections or an insulin pump, which is worn 24 hours a day--can have flexibility in when and what they eat. Other diabetics on insulin therapy must eat at consistent times, synchronized with the time-action of the insulin they use.
In 1996, FDA approved Humalog, which Robert I. Misbin, M.D., an FDA medical reviewer, describes as "a modified human insulin." Humalog is absorbed and dissipated more rapidly than regular human insulin. Humalog is of particular benefit because it offers convenience.
Adults with Type 2 diabetes may or may not be treated with one or more classes of oral diabetes drugs. The oldest class, sulfonylureas (SFUs), act on the pancreatic tissue to produce insulin. The newest one is Amaryl (glimepiride) approved by FDA in 1996.
Because SFUs can become less effective after 10 or more years of use, other drugs often are needed.
Another class is the biguanides, including metformin, which was approved by FDA in 1995. This drug acts by lowering cells' resistance to insulin, a common problem in Type 2 diabetes.
A third class is the alpha-glucosidase inhibitors, which include Precose (acarbose), approved by FDA in 1995, and Glyset (miglitol), approved in 1996. These drugs slow the body's digestion of carbohydrates, delaying absorption of glucose from the intestines.
A newer class of diabetes drugs is the thiazolidinediones. They include Rezulin (troglitazone), approved in 1997, and Avandia and Actos, both approved in 1999. These drugs improve a condition that seems to be an important underlying cause of adult onset diabetes--resistance of the body to insulin.
Though they act similarly, their approved uses vary. Rezulin, for example, is approved for use in combination with sulfonyureas and metformin. It should not be used as an initial single agent therapy and should be prescribed only in patients not adequately controlled by other therapies.
FDA approved Avandia for patients with diabetes who are not taking insulin and Actos for diabetics who are not adequately controlled by diet and exercise alone. Actos is approved for use with sulfonylureas, metformin or insulin in patients who are not adequately controlled on the these agents alone.
FDA recommends regular liver chemistry tests for patients receiving a thiazolidinedione. This recommendation is based on evidence of serious and sometimes fatal liver injury in patients treated with Rezulin. Though liver disease was not seen in clinical trials of Avandia and Actos, FDA recommends liver tests for patients on any of the approved thiazolidinediones. The recommendations are as follows:
- For patients on Rezulin, liver function tests should be done before the patient starts therapy, monthly during the first year of Rezulin therapy, and quarterly thereafter.
- For patients on Actos and Avandia, liver function tests should be performed at the start of therapy, every two months during the first year of treatment, and periodically thereafter.
Symptoms suggesting liver problems include unexplained nausea, vomiting, stomach pain, tiredness, loss of appetite, dark urine or yellowing of skin (jaundice). If any of these symptoms occur, liver enzymes should be checked. If the patient develops jaundice, he or she should stop the drug therapy.
Another new class of oral blood glucose-lowering drugs, the meglitinides, was introduced in December 1997 when FDA approved Prandin (repaglinide). These drugs work like the SFUs.
Prandin is taken two, three, or four times a day usually about 15 minutes before meals. The advantage of this medicine is that, like the short-acting SFUs, it provides convenience to patients who are not on a regular eating schedule. Also, it may reduce the potential for serious hypoglycemia (low blood sugar), the most important adverse reaction of SFU therapy.
Prandin is approved for use alone or in combination with metformin.
Oral diabetes drugs are not without side effects. Metformin, for example, can cause serious cramps and diarrhea, and it can't be used in people with kidney problems.
Metformin is also not generally used in patients with liver dysfunction. "It should be used only in patients without major health problems and it's not for the elderly," Misbin says.
Precose is less effective but probably safer to use than metformin, he points out. Precose's one major side effect is flatulence. Precose stops, or delays, absorption of carbohydrates, causing gas. Flatulence may be reduced by beginning the drug at a low dose.
Product labeling recommends that doctors start patients on lower doses to combat the flatulence problem.
Rezulin was well-tolerated in clinical studies. The most commonly reported side effects were infection, pain and headache, but these occurred at rates comparable to those in the placebo-treated patients. Rezulin should not be used in patients with liver or heart disease. Side effects include (in addition to the most serious, liver injury) fluid retention and weight gain.
Possible side effects of Avandia are mild to moderate water retention, increased blood cholesterol levels and anemia, although in clinical studies, none of these problems led to the discontinuation of Avandia treatment.
Side effects of Actos are mild to moderate water retention and anemia.
Choosing the Right Treatment
Some diabetes experts report that when it comes to prescribing initial therapy for Type 2 diabetics, some doctors tend to follow a "treatment of laziness"--for example, prescribing SFUs if they perceive difficulties in the patient's ability to change dietary habits or lifestyle.
"Sometimes, patients with diabetes are treated with drugs when it's not really necessary," Misbin says. "Oral pills should be used in Type 2 diabetes only when diet and exercise are not effective. It's very common for overweight patients who lose weight to lower their own blood sugar levels and come off the medicines. The problem is that it's very difficult to get patients to lose weight."
So, the bottom line in diabetes control still hinges on patients' ability to manage the disease themselves. "I don't know of a chronic disease in which the person who suffers from it is so responsible for its management," says ADA president Cryer. "The patient has to become an expert regarding his or her own diabetes."
Although drug treatment makes a difference to many diabetics and their quality of life, Cryer adds that current diabetes treatments are still "not ideal." He hopes that continuing research will someday find the answer to the diabetes dilemma.
Paula Kurtzweil is a member of FDA's public affairs staff. Audrey Hingley is a writer in Mechanicsville, VA.