Obese persons with excess visceral fat have increased risk of diabetes

by Bruce Sylvester – Obese persons with excess visceral fat appear to be at an increased risk of developing Type 2 diabetes, researchers reported on September 18, 2012 in the obesity-themed issue of the Journal of the American Medical Association.

“Among obese individuals, it is not necessarily how much fat a person has, but rather where the fat is located on a person that leads to diabetes,” said investigator and lead author,  James de Lemos, MD, professor of internal medicine at the University of Texas Southwestern Medical Center in Dallas.

The investigators used imaging techniques to identify location and function of body fat. The study included the largest number yet of obese people to undergo extensive body-fat imaging in a single study.

“Understanding the biological differences between visceral fat and subcutaneous fat may help doctors to more effectively battle the obesity epidemic occurring in the United States,” Dr. de Lemos added. “The risk for diabetes varies widely among different obese individuals, and this study suggests that by predicting who will get diabetes, it may be possible to target intensive lifestyle, medical, and surgical therapies for those at a higher risk.”

The researchers did a sub-analysis of data from UT Southwestern’s Dallas Heart Study, including 732 adults  with a body mass index of 30 or greater . All were 30 and 65 years-old, and did not yet have diabetes or cardiovascular disease.

At enrollment, the investigators used magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DEXA) to determine fat location.

At follow-up after seven years, 11 percent of the subjects had developed diabetes. Among the participants who had normal glucose at baseline testing, 39 percent had developed prediabetes or diabetes.

Subjects who had developed prediabetes and diabetes had, at baseline, more visceral fat and greater insulin resistance compared to subjects who did not develop prediabetes and diabetes

“We found that individuals who developed prediabetes and diabetes had evidence of early cardiovascular disease years before the onset of diabetes,” said Ian Neeland, MD,  cardiology fellow at UT Southwestern and an author of the study. “This finding suggests that excess visceral fat and insulin resistance may contribute to cardiovascular disease among obese individuals.”

The Dallas Heart Study is a multi-ethnic population-based study of 6,101 adults from Dallas County.  It was designed to identify new genetic, protein, and imaging biomarkers to help detect cardiovascular disease at its earliest stages.