Diabetes Is Where the Fat Is

For the most part, the more fat you carry, the higher your risk of type 2 diabetes. But how much fat you have may not be the only factor that boosts your risk of diabetes. Where that fat is located may also play a role.

Obese people with higher amounts of visceral fat (abdominal fat around the body's internal organs) may have an increased risk of type 2 diabetes.

In contrast, obese people with higher amounts of total body fat and subcutaneous fat (fat under the skin) may not have this increased risk.

Exercise to shed fat and prevent diabetes.

While obesity increases the risk of type 2 diabetes, not all obese people have the same diabetes risk.

James de Lemos, MD, professor of internal medicine at UT Southwestern, and colleagues wanted to see if the location of fat played a role in the development of prediabetes and diabetes in obese people.

"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 Dr. de Lemos.

Using magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DEXA), the researchers located where obese patients were storing fat in the body.

After a period of 7 years, 11.5 percent (84 out of 732) of the study's participants developed diabetes. A number of factors were associated with the development of diabetes. These included:

• higher amounts of visceral fat at the beginning of the study
• fructosamine levels - a measure of the average plasma glucose (blood sugar) levels over several weeks
• fasting glucose level - a measure of blood sugar without eating
• family history of diabetes
• systolic blood pressure, or blood pressure as the heart pumps
• weight gain during the 7-year course of the study

Of those patients with normal blood sugar at the beginning of the study, 39.1 percent (about 200 of 512) developed diabetes or prediabetes - a condition in which blood sugar levels are high but not high enough to be diagnosed as diabetes.

Compared to obese patients who stayed healthy, those who developed prediabetes and diabetes had higher levels of visceral fat and insulin resistance.

Insulin resistance means the body does not properly use insulin - a hormone that helps manage levels of sugar in the blood. Without insulin, blood sugar levels can rise to dangerous levels, leading to diabetes and other complications.

"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, a cardiology fellow and first author of the study.

"This finding suggests that excess visceral fat and insulin resistance may contribute to cardiovascular disease among obese individuals," he said.

According to the authors, more research is needed to see if assessing fat location can improve the prediction of diabetes risk in obese people.

The study was published September 19 in The Journal of the American Medical Association (JAMA).