By Annie Hauser
Where and how your body stores fat -- specifically fat stored in the abdomen around the organs -- could be the key to your type 2 diabetes risk, finds an observational study published in the Journal of the American Medical Association's special issue on obesity.
The study, which tracked the 6,000 participants in the Dallas Heart Study, is the largest of its kind to assess the diabetes risk of a multiethnic population of only obese people, meant to mimic the ethnic composition of the country as a whole.
Using imaging techniques, researchers at the University of Texas Southwestern Medical Center were able to identify obese people who were at a higher risk for diabetes -- years before the disease appeared. After testing participants for body composition and biomarkers, such as insulin resistance and blood-sugar levels, they concluded that body mass index, HDL cholesterol, and body-fat percentage did not impact type 2 diabetes risk, but the level of visceral fat, or fat stored in the abdomen around the organs, did.
Key Diabetic Risk Factors
"Diabetes was linked to fat around the organs, not subcutaneous fat, not total body fat, and not body mass index," says lead researcher James de Lemos, MD, professor of internal medicine at UT Southwestern. He noted that previous research has shown that fat in the lower body can have a protective effect against heart disease and diabetes in some people, particularly women, but the positive effects of fat storage were not analyzed in this study.
In people who had a normal fasting glucose at the beginning of the study, their age, ethnicity, and additional weight gain over the course of the eight-year study appeared to determine their diabetes or prediabetes risk. (As people age, their diabetes risk increases.)
"Additional weight gain in obese people was the most powerful predictor of who would develop diabetes or prediabetes," de Lemos says. "If [clinicians] can prevent additional weight gain, we can do a lot to prevent diabetes."
Although the study did not directly test clinical implications, de Lemos believes this data can be used in a clinical setting to predict which obese patients will develop diabetes -- and eventually, to target diabetes-prevention therapies. Lifestyle interventions, prescription weight-loss supplements that can help shift the location of fat deposits, and even weight-loss surgery are all clinical actions that could be taken if someone is determined to have a higher diabetes risk. "Some therapies can carry substantial risk and expense and might be best targeted toward those who are high-risk for diabetes," de Lemos explains.
The key take-away message, de Lemos says, is that obese patients are not all alike and should not be treated that way.
"There's no association between markers of general adipositivity and prediabetes," he says. "Obesity is a heterogeneous or variable disorder, and we can characterize specific subgroups that have a greater or lesser risk of developing diabetes -- with clinical implications."