Body mass index (BMI) is a proxy measure of a person’s fat composition and is calculated by dividing a person’s weight (kg) by their height (m2). BMI values above 30 fall into the obese category and are known to carry an increased risk of developing type 2 diabetes. Those individuals with BMI values in the 25 to 30 range are considered overweight and also carry an increased, although lower, risk of developing type 2 diabetes. The worldwide type 2 diabetes rate has continued to rise which has been driven partly by the obesity epidemic occurring in the industrialized nations. Identifying those individuals that are overweight with greatest risk of developing diabetes is important because they can be targeted for weight loss in an effort to prevent the occurrence of diabetes.
Researchers involved in The InterAct Consortium have found that individuals that are overweight with larger waist circumferences (WC) have the greatest risk of developing type 2 diabetes. The results of their study were published online in the journal PLoS Medicine. The investigators used a prospective case-cohort study conducted in 26 centers in eight European countries to study the correlation between BMI and WC with the incidence of type 2 diabetes. As previously known, BMI showed a linear correlation with the risk of developing type 2 diabetes. In those individuals that are overweight, it was found that larger WC was predictive of increased risk of developing type 2 diabetes.
The authors wrote, “Among the large group of overweight individuals, WC measurement was highly informative and facilitated the identification of a subgroup of overweight people with high WC whose 10 year type 2 diabetes cumulative incidence was comparable to that of the obese group”. The authors concluded, “Our results clearly show the value that measurement of WC may have in identifying which people among the large population of overweight individuals are at highest risk of diabetes”.
This study has shown that waist circumference is independently and strongly associated with increased risk of developing type 2 diabetes, especially among females. One third of the population in the United States is overweight. We have previously discussed the finding that modest weight loss can prevent the progression to type 2 diabetes. Individuals that are overweight with larger waist circumferences have the greatest risk of developing type 2 diabetes and they should be targeted for more aggressive weight loss in order to prevent type 2 diabetes. Future studies should determine the amount of weight loss needed in this high risk overweight group that would be needed to decrease the risk of developing type 2 diabetes.
The InterAct Consortium (2012) “Long-Term Risk of Incident Type 2 Diabetes and Measures of Overall and Regional Obesity: The EPIC-InterAct Case-Cohort Study” PLoS Med 9(6): e1001230. doi:10.1371/journal.pmed.1001230