As a young individual who lives in Dallas, Houston, Austin or other locations in Texas, you try to stay in shape. But maybe you're still carrying a few extra pounds. Medical professionals have already linked your spare tire to the increased risk of diabetes. Now doctors are saying that upper trunk fat, which are deposits of fat on your chest and back, is associated with an increased risk of insulin resistance. And, as most of us know, this is a condition that is a precursor to type 2 diabetes. This is the first time an association like this has been demonstrated, medical researchers report.



This association was equal in both HIV and HIV-negative control subjects in the recent Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM). This is a national long-term longitudinal study of HIV-infected individuals taking modern antiretroviral therapy as well as HIV-negative controls.

The presence of visceral fat located between and around the internal organs was also associated with an increased risk of insulin resistance in both study groups. Researchers found that each type of fat contributes independently to insulin resistance, regardless of whether the other type of fat was present.

Lead author and FRAM principal investigator Carl Grunfeld, MD, PhD, chief of the metabolism and endocrine sections at SFVAMC explains, "We knew about the insulin resistance risk associated with visceral fat, which has been shown in previous studies, but no one had ever looked at the contribution of upper trunk fat. Strikingly, there was very little difference between HIV- infected people and controls. If you have fat up top, it's bad for you."

With insulin resistance, body cells become increasingly resistant to the action of insulin, which is a hormone that regulates blood glucose levels. The result is consistently high blood glucose having many negative effects on an individual's health.

Researchers measured visceral and subcutaneous fat deposits in the legs, arms, upper trunk, and lower trunk of 926 HIV-infected subjects and 258 HIV-negative controls. Each group was divided into thirds, based on the amount of fat in each location. With the HIV infected subjects in the highest third of upper trunk fat, 57 percent showed insulin resistance. Within that group, half did not have high visceral fat. Among the highest third of control groups with upper trunk fat, 61 percent were insulin resistant. Again, a third of that group did not have high visceral fat.

"So, basically, there are people who have a lot of fat in their upper trunk and not so much inside their belly, yet they are at risk for insulin resistance," reports Grunfeld, who is also a professor of medicine at the University of California, San Francisco (UCSF). "And there are people with a lot of visceral fat but not upper trunk fat who are in the same boat. But if you've got both, it's a double whammy. Your risk of insulin resistance is quite high."

Researchers also looked at all regions of the body where fat is deposited in order to investigate abnormalities in fat distribution that have been reported in HIV infection. In particular, there is the "buffalo hump," a prominent fat deposit in the middle of the upper back. "But we found that fat in that area was present, and associated with the same risk for insulin resistance, in both HIV infected and control subjects," Grunfeld says.

He further explains that there is a lack of difference in risk between HIV- infected and HIV- negative subjects,; noting that two- thirds of all Americans are overweight and one- third are obese. "With the new, highly effective antiretroviral medications, Americans with HIV now have the same weight problems as everybody else," he says. "No matter who you are, if you eat too much and you don't exercise, you're going to be at risk for insulin resistance, cardiovascular disease, and every other problem associated with being overweight."

Minding your weight and your health will certainly affect you as you age, and eventually affect your wallet as well.