Distribution of diacylglycerols among plasma lipoproteins in control subjects and in patients with non-insulin-dependent diabetes

Background Diacylglycerols (DAGs), which are well-known components of insec t lipophorins, have been recently recognized as a major glyceride of human high-density lipoprotein (HDL). Moreover, DAGs are good substrates for hepa tic lipase and for the phospholipid transfer protein (PLTP). The present wo rk was undertaken to determine the lipoprotein concentrations of DAGs, in c ontrol subjects, in non-insulin-dependent diabetic (NIDD) patients and in p atients with severe hypertriglyceridaemia. Materials and methods Lipoproteins were isolated from 11 control subjects, 17 diabetic patients and three hypertriglyceridaemic patients, using a comb ination of ultracentrifugation and precipitation. After lipid extraction, D AGs were separated by thin-layer chromatography and quantified by a glyceri de assay. Results DAGs were detectable in all lipoprotein fractions of the three grou ps of subjects. Total DAGs were correlated with total triglycerides (TGs) a nd even more strikingly with very low-density lipoprotein triglycerides. Al though the majority of DAG was recovered in apo B-containing lipoproteins, the proportion of DAG with respect to TG was most elevated in HDL. Conclusion These findings indicate that DAGs are probably formed from TG du ring lipolysis and that they can be transported to HDL through the action o f PLTP. This raises the question whether DAG might act as an inhibitor of p hospholipid transfer by competition for binding to PLTP.