Intra-abdominal fat: is it a major factor in developing diabetes and coronary artery disease?

Abdominal obesity has emerged as a strong and independent predictor for non-insulin dependent diabetes mellitus (NIDDM). Adiposity located centrally in the abdominal region, and particularly visceral as opposed to subcutaneous fat, is also distinctly associated with hyperlipidemia, compared with generalized distributions of body fat. These lipoprotein abnormalities are characterized by elevated very low density lipoprotein (VLDL) and low density lipoprotein (LDL) levels, small dense LDL with elevated apolipoprotein B levels, and decreased high density lipoprotein2b (HDL2b) levels. This is the same pattern seen in both familial combined hyperlipidemia and NIDDM. The pronounced hyperinsulinemia of upper-body obesity supports the overproduction of VLDL and the increased LDL turnover. We have proposed that an increase in the size of the visceral fat depot is a precursor to the increased lipolysis and elevated free fatty acid (FFA) flux and metabolism and to subsequent overexposure of hepatic and extrahepatic tissues to FFA, which then, in part, promotes aberrations in insulin actions and dynamics. The resultant changes in glucose/insulin homeostasis, lipoprotein metabolism, and vascular events then lead to metabolic morbidities such as glucose intolerance, NIDDM, dyslipidemia, and increased risk for coronary heart disease.