The recognition that the increase of plasma triglyceride rich lipoproteins (TRLs) is associated with multiple alterations
of other lipoproteins species that are potentially atherogenic has expanded the picture of diabetic dyslipidaemia. The discovery
of heterogeneity within major lipoprotein classes VLDL, LDL and HDL opened new avenues to reveal the specific pertubations
of diabetic dyslipidaemia. The increase of large VLDL 1 particles in Type 2 diabetes initiates a sequence of events that generates
atherogenic remnants, small dense LDL and small dense HDL particles. Together these components comprise the atherogenic lipid
triad. Notably the malignant nature of diabetic dyslipidaemia is not completely shown by the lipid measures used in clinical
practice. The key question is what are the mechanisms behind the increase of VLDL 1 particles in diabetic dyslipidaemia? Despite
the advances of recent years, our understanding of VLDL assembly and secretion is still surprisingly incomplete. To date it
is still unclear how the liver is able to regulate the amount of triglycerides incorporated into VLDL particles to produce
either VLDL 1 or VLDL 2 particles. The current evidence suggests that the machinery driving VLDL assembly in the liver includes
(i) low insulin signalling via PI-3 kinase pathway that enhances lipid accumulation into "nascent " VLDL particles (ii) up-regulation
of SREBP-1C that stimulates de novo lipogenesis and (iii) excess availability of "polar molecules" in hepatocytes that stabilizes
apo B 100. Recent data suggest that all these steps could be fundamentally altered in Type 2 diabetes explaining the overproduction
of VLDL apo B as well as the ability of insulin to suppress VLDL 1 apo B production in Type 2 diabetes.
Recent discoveries have established the transcription factors including PPARs, SREBP-1 and LXRs as the key regulators of lipid
assembly in the liver. These observations suggest these factors as a new target to tailor more efficient drugs to treat diabetic
dyslipidaemia.
Keywords Lipids - apoliproteins - insulin - Type 2 diabetes - liver fat - coronary heart disease - stable isotopes - transcription factors
*The 38th Claude Bernard Lecture of European Association for the Study of Diabetes