Abnormalities in the metabolism of postprandial and fasting triglyceride-rich lipoprotein subfractions in normal and insulin-dependent diabetic subjects: effects of sex.

To investigate the effect of sex and diabetes on postprandial lipoprotein metabolism, 15 normal and 12 normolipidemic subjects with insulin-dependent diabetes mellitus (IDDM) were studied. Plasma triglyceride (TG) levels were measured and three TG-rich lipoprotein subfractions (Sf greater than 400, 100 to 400, and 20 to 100) were isolated and their composition analyzed before and every 1.5 hours for a total of 7.5 hours following ingestion of corn oil. Normal women compared with men had lower postprandial plasma TG levels (P less than .05) mostly due to lower TG in Sf 100 to 400. The composition of Sf 100 to 400 and Sf 20 to 100 lipoproteins differed in the two sexes (P less than .01), with normal women having particles poorer in TG in both the fasting and postprandial states. Diabetic men compared with normal men had smaller Sf greater than 400 particles following fat ingestion, as shown by a lower TG protein (PR) ratio (7.6 v 12.8, respectively, P less than .05). The composition of Sf 100 to 400 and 20 to 100 lipoproteins was abnormal in IDDM men due to enrichment in total cholesterol (TC) as shown by higher TC/TG, TC/PR, and TG/phospholipid (PL) ratios in both the fasting (P less than .03 to P less than .003) and the postprandial state (P less than .03 to P less than .0001). A lower PL and TG content was also consistently present. A similar enrichment in TC was observed in diabetic v normal women following fat ingestion in Sf greater than 400 only (P less than .003).(ABSTRACT TRUNCATED AT 250 WORDS)