A little-known but widespread diabetes risk


Some 21 million men and women in this country have a condition that puts them at high risk for developing diabetes--the leading cause of blindness, foot and leg amputations, and advanced kidney disease as well as a major contributor to heart attacks and strokes. The condition is called impaired glucose tolerance (IGT). Like diabetes, it is characterized by high blood levels of glucose, or blood sugar. The levels just aren't as high as in people with diabetes itself.

Most people afflicted with IGT are not aware that they have it. That is particularly unfortunate, given that stepping up physical activity just moderately and losing only a small amount of excess weight may keep diabetes from developing. The preliminary evidence for those lifestyle changes is so compelling, in fact, that the National Institute of Diabetes and Digestive and Kidney Diseases has allocated $130 million to the Diabetes Prevention Program. This 6-year project, to be conducted in conjunction with the Centers for Disease Control and Prevention and the American Diabetes Association, will include 4,000 volunteers with IGT at 25 centers across the country.

The program's organizers hope to show that diabetes can be prevented or delayed in people with IGT who achieve--and maintain--a 7 percent weight loss and increase their physical activity by just 700 calories a week (roughly equivalent to 30 minutes of brisk walking every other day). There's good reason to believe such efforts will be successful. A smaller study has shown that overweight people with IGT who lose just 10 pounds reduce their risk of developing diabetes by 30 percent. In addition, in a 6-year preliminary study in Sweden, only 11 percent of patients with IGT who engaged in exercise went on to develop diabetes, in contrast to 29 percent of patients who were not active.

A proactive approach for those at risk
Those at greatest risk for IGT--as well as for diabetes itself--include men and women over 45 who are both sedentary and overweight. People with that duster of risk factors should get tested, says Belinda Childs, a registered nurse who serves as co-president of the American Diabetes Association. Anyone with 2 of those 3 risk factors who also has a family history of diabetes or who has given birth to a baby weighing more than 9 pounds should also discuss testing with a doctor. This advice is particularly important for groups at high risk: African-Americans, Hispanic-Americans, Asian-Americans, and Native Americans.

Screening for IGT is similar to testing for diabetes. Both require a set of blood tests. The difference is in the numbers that come back from the lab (see below). People should be aware of the cutoff points. "A lot of times doctors themselves don't know the trigger numbers," says Ms. Childs. "You need to be your own health care advocate."

Two tests are generally involved. One is the fasting plasma glucose test, in which blood is drawn after a 10-hour fast. The other is the oral glucose tolerance test (OGTT), which measures plasma glucose 2 hours after the patient drinks a standardized sugar solution. Here's how to decipher the results:

Impaired Glucose Tolerance--fasting plasma glucose less than 140[*] and plasma glucose on the OGTT greater than 140[*] but less than 200

Diabetes--2 fasting plasma glucose readings greater than 140, or plasma glucose on the OGTT greater than 200, or plasma glucose (on a random test, not an OGTT) greater than 200 and classic diabetes symptoms, such as frequent thirst, frequent urination, blurred vision, or slow healing of sores

* All measurements are milligrams per deciliter of blood.

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Participants are still being sought for the Diabetes Prevention Program. Potential volunteers will be screened to determine if they have impaired glucose tolerance and are eligible.

Some of those who qualify will be assigned to an intensive lifestyle modification program that includes individual and group training in weight loss, dietary fat restriction, and exercise. Flexible regimens will be prescribed that meet individual needs and cultural differences.

Other volunteers will be assigned to take 1 of 2 drugs. Metformin (trade name Glucophage) prevents the liver from producing too much sugar, thereby preventing high levels of sugar in the blood. Troglitzone, an experimental drug, allows the body's cells to take up glucose from the blood more efficiently and use it for fuel.

Anyone interested in finding out whether he or she might be eligible for the program can call 1-888-DPP-JOIN (377-5646).

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