Apolipoprotein A-IV in diabetes mellitus.

Apolipoprotein A-IV is considered to play a role in triglyceride-rich lipoprotein metabolism, in reverse cholesterol transport, and in facilitation of CETP (Cholesterolyl Ester Transfer Protein) activity. Moreover, apoA-IV is genetically polymorphic in humans, in whom two major isoproteins (apoA-IV 1 and apoA-IV 2) are present and have differences that influence the apoA-IV phenotype in lipid metabolism. In non-insulin-dependent-diabetes, increased apoA-IV levels are found, mainly related to hypertriglyceridemia and to a lesser extent to HDL cholesterol level; apoA-IV phenotype distribution is not different from controls; in the control population, the potential protective lipid profile (characterized by increased HDL and HDL2 cholesterol levels) related to the apoA-IV 1-2 phenotype, is no longer found in NIDDM patients (the metabolic state of NIDDM appears to have effected the potential protective lipid profile related to the apoA-IV 1-2 phenotype); and plasma apoA-IV levels is associated with increased prevalence for macrovascular disease. In non-insulin-dependent diabetes treated with insulin, apoA-IV levels are increased. Unlike results for NIDDM patients undergoing oral treatment, the increase in apoA-IV level is not related to hypetriglyceridemia, so that the effect on lipid metabolism may be different.