Postprandial VLDL-triacylglycerol secretion is not suppressed in obese type 2 diabetic men.

ABSTRACT

AIMS/HYPOTHESIS: Type 2 diabetes is characterised by insulin resistance and increased post-absorptive secretion of VLDL-triacylglycerol (VLDL-TAG). Whether postprandial suppression of endogenous VLDL-TAG secretion is abnormal--a finding that would link hyperlipidaemia and type 2 diabetes--remains unclear. METHODS: Eight type 2 diabetic men and eight healthy men were studied before and after a fat-free test meal (40% of resting energy expenditure). VLDL-TAG kinetics were assessed using a primed-constant infusion of ex vivo labelled [1-(14)C]triolein VLDL-TAG using non-steady-state calculations. RESULTS: Type 2 diabetic men had a higher basal VLDL-TAG secretion rate and concentration than healthy men (mean ± SD secretion rate 137 ± 61 vs 78 ± 30 µmol/min, respectively [p = 0.03]; median concentration 1.03 [range 0.58-1.75] vs 0.33 [0.13-1.14] mmol/l, respectively [p < 0.01]). Postprandially, the VLDL-TAG secretion rate decreased in healthy men (p < 0.01), but remained unchanged in diabetic men (p = 0.47). The VLDL-TAG concentration increased in diabetic men and decreased in healthy men postprandially (p < 0.05). The difference in VLDL-TAG secretion rate between the two groups approached significance (p = 0.06) and the relative change in VLDL-TAG secretion rate was significantly different (p = 0.01) between the two groups. Basal VLDL-TAG clearance was significantly lower in diabetic men (diabetic men 133 [49-390] ml/min; healthy controls 215 [137-933] ml/min [p < 0.05]). After meal ingestion, clearance decreased in healthy men (p = 0.03), but was unchanged in diabetic men (p = 0.58). CONCLUSIONS/INTERPRETATION: Obese type 2 diabetic men have impaired postprandial suppression of VLDL-TAG secretion compared with lean healthy men, contributing to their postprandial lipaemia and hypertriacylglycerolaemia.