LIPOPROTEIN COMPOSITIONAL CHANGES IN THE FASTING AND POSTPRANDIAL STATE ON A HIGH-CARBOHYDRATE LOW-FAT AND A HIGH-FAT DIET IN SUBJECTS WITHNONINSULIN-DEPENDENT DIABETES-MELLITUS

Our aims were 1) to examine the effects of a high-carbohydrate low-fat diet on fasting and postprandial plasma lipids, apolipoproteins (apo) , and lipoprotein composition in noninsulin-dependent diabetes mellitu s, and 2) to determine whether postprandial shift of apo between trigl yceride-rich lipoproteins (TRLP) and high density lipoproteins (HDL) i s affected by diet. A cross-over study, of 4 weeks duration, of a high -carbohydrate (60% carbohydrate, 20% fat) and a high-fat (40% carbohyd rate, 40% fat) diet was performed in seven subjects with noninsulin-de pendent diabetes mellitus. TRLP, low density lipoproteins (LDL), and H DL were separated by fast protein liquid chromatography. The high-carb ohydrate diet resulted in a decrease of fasting total, HDL, and LDL ch olesterol and a trend toward an increase in plasma triglycerides. The apo composition of fasting TRLP and HDL was similar on both diets. TRL P apo CII, CIII, and E increased whereas HDL apo CII, CIII, and E decr eased postprandially on both diets. In contrast, TRLP apo CI increased , and HDL apo CI decreased only after the high-carbohydrate diet. We c onclude that 1) a high carbohydrate diet results in a decrease in tota l, LDL, and HDL cholesterol and a trend toward an increase in plasma t riglycerides; 2) fasting TRLP and HDL apo composition was similar on a high-carbohydrate or a high-fat diet; and 3) on both diets, apo CII, CIII, and E transfer from HDL to TRLP postprandially. However, only th e high-carbohydrate diet induced postprandial transfer of apo CI from HDL to TRLP. This may explain in part the changes in lipoproteins obse rved with this diet.