Women’s habits can reduce risk of diabetes

Researchers from the School of Public Health and Brigham and Women’s Hospital have found that women who are not overweight, exercise at least half an hour a day, and eat a diet rich in fiber and low in glycemic index and trans fat dramatically reduce their risk of Type 2 diabetes. The study results appear in the Sept. 13 issue of the New England Journal of Medicine (http://www.nejm.org).

Using the Nurses’ Health Study, a Brigham and Women’s Hospital-based study, the researchers tracked diet and lifestyle habits of 89,941 women from 1980 to 1996 via biennial questionnaires. At the start of the study the women had to be free of diabetes, cancer, or cardiovascular disease. During the 16 years, 3,300 new cases of Type 2 diabetes were diagnosed. Type 2 diabetes usually occurs after age 40. People with this type of diabetes do not produce adequate amounts of insulin for the needs of the body and/or cannot use insulin effectively.

The study found that obesity (determined by body mass index) was the single most important predictor of diabetes. The authors found that 61 percent of the cases of Type 2 diabetes in the study could be attributed to overweight and obesity. Lack of exercise, a diet high in trans fat intake and high glycemic index, smoking, and abstinence from alcohol were also associated with a significant increased risk for diabetes, independent of obesity. Small amounts of alcohol are known to protect against heart disease. Women who were not overweight, consumed a diet low in trans fat (found in hydrogenated vegetable oils), high in polyunsaturated fat (found in natural vegetables oils) and cereal fiber, exercised for at least 30 minutes a day, had on average at least half an alcoholic drink per day (5 grams of alcohol) and didn’t smoke, reduced the risk of developing Type 2 diabetes by 90 percent when compared with the rest of the women. The authors have previously found that a healthy lifestyle can also dramatically reduce risk of heart disease.

Frank Hu, lead author and an assistant professor in the Department of Nutrition at the School of Public Health, said, “Type 2 diabetes is reaching epidemic proportions in the U.S. and other countries. The good news is that the epidemic can be reversed by moderate lifestyle modifications. Unfortunately, so few Americans are willing to make the change and follow this sort of healthy lifestyle.”

Hu emphasized that these findings corroborate results from recent prevention trials of Type 2 diabetes through lifestyle modification in high-risk populations in Finland and the United States.

The research was supported by grants from the National Institutes of Health and by a research award from the American Diabetes Association.