Insulin and non-esterified fatty acid relations to alimentary lipaemia andplasma concentrations of postprandial triglyceride-rich lipoproteins in healthy middle-aged men

Aims/hypothesis. Enhanced and prolonged postprandial lipaemia is related to cardiovascular disease but how postprandial lipaemia is regulated is poorl y known. We therefore determined the relations of fasting insulin concentra tions to fasting and postprandial lipids, lipoproteins and non-esterified f atty acids in middle-aged men. Methods. The subjects, 99 healthy 50-year-old men with an apolipoprotein E3 /3 genotype, ate a mixed meal. The apolipoprotein B-48 and B-100 contents w ere determined in triglyceride-rich lipoproteins as a measure of chylomicro n remnant and very low density lipoprotein particle concentrations. Results. Fasting plasma insulin was associated with th.e triglyceride respo nse to the test meal, independently of body mass index, waist-to-hip circum ference ratio, blood glucose and the insulin effect on fasting plasma trigl ycerides. Exaggerated and prolonged postprandial lipaemia in subjects in th e upper quartile of the plasma insulin distribution was largely accounted f or by large (Svedberg flotation rate > 60) very low density lipoproteins an d chylomicron remnants. Insulin relations to large postprandial triglycerid e-rich lipoproteins exclusively reflected the association between plasma in sulin and the fasting plasma concentrations of these lipoprotein species, w hereas plasma insulin and late postprandial plasma concentrations of small (Svedberg flotation rate 20-60) chylomicron remnants were related, independ ently of insulin influences on fasting concentrations. Strong positive rela tions were found between the late increases in large triglyceride-rich lipo proteins and plasma non-esterified fatty acid concentrations after 6 h. Conclusion/interpretation. The degree of insulin sensitivity is a major det erminant of postprandial lipaemia in healthy middle-aged men and could add to the regulation of the basal production of large triglyceride-rich lipopr oteins.