NEW YORK (Reuters Health) - Researchers studying the Pima Indians--a group with one of the highest rates of diabetes in the world--have found two factors that play a key role in the earliest stages of the blood-sugar disorder.

The factors are insulin resistance and insulin secretory dysfunction, according to a report in the January issue of Diabetes Care. Insulin resistance refers to the body's inability to respond to insulin, the hormone that helps ferry blood sugar into body cells. Insulin secretory dysfunction occurs when insulin is not manufactured as needed by the body.

Dr. Christine Weyer and colleagues at the National Institute of Health's Clinical Diabetes and Nutrition Section in Phoenix, Arizona, looked at insulin resistance and insulin secretory dysfunction in a group of 254 Pima Indians. They followed their patients for about up to 9 years and found that insulin resistance and insulin secretory dysfunction independently predicted those patients who would have a decline in glucose tolerance, or the ability to process blood sugar. Deterioration in glucose tolerance is a hallmark of progressive diabetes.

Weyer told Reuters Health that these factors have long been recognized but that ``the relative importance of both abnormalities at different stages of disease development have been a matter of debate for decades.''

Specifically, Weyer explained, evidence has pointed to insulin resistance as the ``primary abnormality'' leading to diabetes, with insulin secretion defects becoming important ``only at a later stage.'' On the other hand, there are those who hold that insulin secretion problems are the important early factor.

However, Weyer and her team concluded that both insulin resistance and insulin secretory dysfunction ``appear to play a role from the earliest stages of the disease and continue to do so as the disease progresses,'' she said.

The findings should play a key role in identifying effective ways to prevent diabetes, the researcher added, and ``strategies aimed at preventing diabetes may be most effective when both defects are targeted.''

Weyer's future research efforts will look at determining which genetic and environmental factors increase the risk of developing insulin resistance and/or insulin secretion problems. SOURCE: Diabetes Care 2000;24:89-94.

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