Lipoproteins and plasma cholesterol esterification in normal and diabetic subjects.

Serum lipoproteins, separated by preparative ultracentrifugation and the activity of the plasma enzyme lecithin: cholesterol acyltransferase (LCAT) have been measured in insulin-dependent diabetics, non-insulin-dependent diabetics and in age-matched non-diabetic controls. In the insulin-dependent diabetics, mean total serum cholesterol and high density lipoprotein cholesterol (HDL-C) concentrations were significantly higher than in controls. Non-insulin-dependent diabetics had significantly raised total triglycerides and cholesterol, but HDL-C levels were essentially normal. The increased low density lipoprotein cholesterol (LDL-C) in both diabetic groups was statistically significant in men. A methodological study of HDL separation techniques was carried out to facilitate interpretation of these findings. Mean LCAT activity, by a method reflecting combined enzyme and substrate effects was significantly increased in these diabetic groups. The results confirm recent reports of a raised HDL-C in those insulin-dependent diabetics who are prone to coronary heart disease.