Tummy size an indicator of potential diabetes

A study by Youfa Wang, PhD, MD, assistant professor with the Centre for Human Nutrition at the Johns Hopkins Bloomberg School of Public Health, published in the current issue of the American Journal of Clinical Nutrition, has found that the size of a man's waist is a better predictor of his risk of developing type 2 diabetes than his body mass index (BMI).

Based on data collected from 27,270 men tracked over 13 years who participated in the Harvard Health Professionals Follow-Up Study, it was found that men who had larger waists or higher overall body fat had a greater risk of developing type 2 diabetes.

The men were placed into five groups according to their waist size. Compared to those in the group with the smallest waists (29-34 inches), the other groups (34.-35.9 inches, 36-37.8 inches, 37.9-39.8 inches, 40-62 inches) were 2, 3, 5 and 12 times more likely to develop diabetes, respectively. Similarly, risk was 2, 3, 4 and 7 times greater when waist-hip ratio was measured in men; and 1, 2, 3 and 8 times greater when BMI was measured.

Dr.Wang says that both BMI and waist circumference are useful tools to assess health risk, but abdominal fat measured by waist circumference can indicate a strong risk for diabetes whether or not a man is considered overweight or obese according to his BMI. The research suggests that the currently recommended waist circumference cut-off of 40 inches for men may need to be lowered as many of the men who developed type 2 diabetes had measurements lower than the cut-off.

While nearly 80 percent of the men in this cohort who developed type 2 diabetes could be identified using a BMI of 25 - the cut-off for overweight - only half (50.5 percent) had a waist circumference greater than or equal to 40 inches?the cut-off recommended by the National Institutes of Health.

Men with waist circumference of 40 inches or greater and who also fell into the obese category with a BMI of 30 or greater were at more than twice the risk to get type 2 diabetes as were those who had a high BMI or a high waist circumference alone. In addition to measuring BMI, the investigators recommend that physicians and researchers measure waist circumference instead of the waist-to-hip ratio because it is a better measure of central obesity for predicting the risk of type 2 diabetes and is subject to fewer measurement errors.

The study authors also urge that more research on this topic be conducted with women and different ethnic and racial groups, since the Health Professionals Follow-Up Study only followed a group of largely white, professional men who are likely to be healthier than the average American.

"Comparison of abdominal adiposity and overall obesity in predicting risk of type 2 diabetes among men" was written by Youfa Wang, Eric B. Rimm, Meir J. Stampfer, Walter.