“Apple-Shaped” Body Type May Increase Diabetes, Heart Disease Risk

A newstudypublished inJAMAfound a casual association between abdominal adiposity and the development of type 2 diabetes (T2D) and coronary heart disease (CHD).

Prior studies have shown an association betweenabdominal adiposityand CHD and T2D; however, whether the associations were representative of casual relationships was unknown.

“People vary in their distribution of body fat—–some put fat in their belly, which we call abdominal adiposity, and some in their hips and thighs,” said senior author Sekar Kathiresan, MD. “Abdominal adiposity has been correlated with cardiometabolic disease, but whether it actually has a role in causing those conditions was unknown. We tested whether genetic predisposition to abdominal adiposity was associated with the risk for type 2 diabetes and coronary heart disease and found that the answer was a firm ‘yes.’”

For the study, investigators sought to determine whether genetic evidence was consistent with a causal relationship among waist-to-hip ratio (WHR) adjusted for body mass index (BMI)—–a measure of genetic predisposition to abdominal adiposity––T2D and CHD.

The investigators used the genetic approach Mendelian randomization, which measures whether inherited gene variants cause outcomes such as the development of the disease. A genetic risk score was developed using data from a prior study that identified 48 gene variants associated with WHR adjusted for BMI.

To determine whether there was any association between a genetic predisposition to abdominal adiposity and cardiometabolic disease and its risk factors, the investigators applied the genetic risk score to data obtained from 6 major genome-wide association studies, as well as to individual data from the UK Biobank.

The results of the study indicated that genetic predisposition to abdominal adiposity is associated with significant increases in the incidence of T2D and CHD, plus increases in blood glucose, blood lipids, and systolic blood pressure.

There was no association observed between the genetic risk score and lifestyle factors, according to the study. Additionally, further testing confirmed that only the abdominal adiposity effects of identified gene variants were associated with cardiometabolic risk.

“These results illustrate the power of using genetics as a method of determining the effects of a characteristic like abdominal adiposity on cardiometabolic outcomes,” said lead author Connor Emdin, DPhil. “The lack of association between the body type genetic risk score and confounding factors such as diet and smoking provides strong evidence that abdominal adiposity itself contributes to causing type 2 diabetes and heart disease.

“Not only do these results allow us to use body shop as a marker for increased cardiometabolic risk, they also suggest that developing rugs that modify fat distribution may help prevent these diseases. Future research also could identify individual genes that could be targeted to improve body fat distribution to reduce these risks.”