Influence of morbid obesity and non-insulin-dependent diabetes mellitus on high-density lipoprotein composition and subpopulation distribution.

The chemical composition, subpopulation distribution and peak hydrated density of high-density lipoprotein (HDL) were examined in 18 morbidly obese women with either normal glucose tolerance or with non-insulin-dependent diabetes mellitus (NIDDM), and in 15 age-matched lean control subjects. Similar measurements were made in the morbidly obese subjects after gastric bypass surgery for weight loss. In the diabetic group, HDL was relatively protein-enriched and cholesterol- and cholesterol ester-poor compared with the lean controls. The same trend was seen in the nondiabetic group, although the cholesterol ester difference was not significant. In both cases, both electrophoretic and density gradient analysis showed that plasma HDL contained more of the HDL3 and less of the HDL2 subfractions than that for the lean controls. Following surgery in the diabetic group, the protein percentage of HDL decreased, and that of cholesterol ester increased; for the nondiabetic group, the protein decreased and phospholipid increased. In the diabetic group, a shift of the electrophoretic HDL subpopulation distribution toward more HDL2 accompanied these changes. Average hydrated peak density of HDL shifted from the HDL3 to the HDL2 range for the diabetic group following surgery; for the nondiabetic group the peak density also decreased but still remained within the HDL3 range. In all cases, the differences seen were more pronounced among the diabetic patients. These changes in the properties of HDL after gastric bypass surgery may favorably influence the risk for coronary heart disease usually associated with diabetes.