he American Diabetes Association issued new dietary guidelines yesterday saying people with the disease could eat sweets occasionally as long as they kept their blood sugar levels under control.

The new guidelines are intended to improve the treatment and prevention of diabetes and to simplify the lives of Americans who have it, an estimated 16 million people.

Although many diabetes specialists have advised patients for years that they can consume sugar-laden foods if they control their blood sugar levels, there is still widespread belief that a person with diabetes should never eat concentrated carbohydrates like sweets.

All carbohydrates, be they from pasta, potatoes, cake or cookies, are treated alike under the new guidelines, although they emphasize that people should eat more nutritious foods like fruits and vegetables. Occasional sweet treats are permissible under the guidelines, as long as the total intake of starches and sugars is kept in balance with insulin or other medications and exercise and does not exceed caloric needs.

"We are continuing to try to lessen the burden for patients with diabetes," Dr. Nathaniel Clark, director of the association, said in an interview.

Dr. Judith Fradkin, director of the diabetes division at the National Institutes of Health, praised the new guidelines as "well thought through."

"A lot of people have misconceptions about diabetes and dieting," Dr. Fradkin said. "Some people think sugar is the absolute worst thing for diabetics and that leads to a lot of problems such as diets that are extremely high in fat or protein."

The report emphasizes that there is no one diet for everyone with diabetes. Rather, dietary plans must be individualized, usually with the aid of a dietitian, to accommodate preferences, circumstances and medical factors like the need to lose weight or lower blood cholesterol or blood pressure, said Dr. Christopher Saudek, president of the association and an endocrinologist specializing in diabetes at the Johns Hopkins Medical Center in Baltimore.

Dr. Saudek said that Medicare was considering covering medical nutrition therapy and that other insurers were likely to follow its lead.

The guidelines disregard consideration of a food's "glycemic index," how much a carbohydrate-containing food raises blood sugar when eaten alone. The glycemic index of a baked potato, for example, is the same as that of a Mars bar; when eaten alone both result in a precipitous rise in blood sugar. Knowledge of this ranking has prompted some people with diabetes either to quit eating potatoes or to start eating candy, forgetting that how these foods are usually consumed can have very different effects on blood sugar.

While snacking on a candy bar may have the same effect on blood sugar as snacking on a plain potato, a potato is rarely eaten that way.

The new guidelines, which are in the January issue of Diabetes Care, say studies found no significant differences in blood sugar response to sugary or starchy foods as long as the total amount of carbohydrates was similar. Dr. Saudek cautioned, however, that it can be difficult to calculate the amount of carbohydrates in some foods. The guidelines note that many factors can influence a food's effects on blood sugar, including the type of sugar and starch it contains, how it is processed and whether it is cooked.

The report does condone the use of the four nonnutritive sweeteners approved for use in the United States — saccharin, aspartame, acesulfame potassium and sucralose. But it cautions against using added fructose, a caloric sweetener that has a lesser effect than sucrose on blood sugar, since fructose can raise levels of fats in the blood.

The goal in treating diabetes is to keep blood sugar levels stable all the time since high blood sugar levels increase the risk of complications like heart attacks, strokes and kidney, nerve and blood vessel damage that can result in amputations or loss of vision.

To aid in blood sugar control, the association has added a recommendation: exercise. Not only does moderate exercise lower blood sugar, thus reducing insulin requirements for people with Type 1, or insulin- dependent, diabetes, but it also is a vital element in permanent weight control for the millions of people whose diabetes is caused by obesity.

Of the 16 million Americans with diabetes, about one million have Type 1, once called juvenile diabetes, in which the pancreas's insulin-producing cells fail, necessitating injections of this vital hormone one or more times a day so that blood sugar can be used by cells instead of accumulating in the blood and spilling into the urine.

But the association is especially concerned about the approximately 15 million people with Type 2 diabetes, formerly called adult-onset diabetes, which is now reaching epidemic proportions among American adults and causing an unprecedented rise in diabetes among children.

In Type 2 diabetes, cells that need blood sugar are resistant to the effects of insulin. Studies have shown that insulin resistance most often results from overweight and obesity, the prevalence of which has been soaring. As a result, the incidence of Type 2 diabetes has risen 33 percent since 1990 with 10 million Americans at high risk for developing it. This year nearly 800,000 cases of diabetes will be diagnosed. The disease costs the nation more than $98 billion and claims 187,000 lives a year.

Insulin resistance can be reduced or overcome by weight loss, which can also lower blood fat levels and blood pressure, both of which increase the risk of serious diabetic complications.