Plasma lipoprotein abnormalities in maturity onset diabetes (MOD) reflect both enhanced production and impaired removal of triglyceride-rich lipoproteins. Hyper-glycemia and hyperinsulinemia lead to overproduction of very-low-density lipoproteins by the liver. Fat tolerance is reduced in MOD patients: this might be due to low lipoprotein lipase activity (LLA) and/or to low incorporation of LLA-released fatty acids into adipose tissue glyceride. The finding of abnormal low-density lipoprotein composition, with relative enrichment in triglyceride, suggests remnant particle accumulation.