Effects of glycemic control upon serum lipids and lipid transfers to HDL in patients with type 2 diabetes mellitus: novel findings in unesterified cholesterol status.

Investigate the relations of glycemic levels with plasma lipids and in vitro lipid transfers to HDL in patients with type 2 diabetes mellitus. 143 patients with type 2 diabetes not taking anti-lipidemic drugs were separated into 2 groups: group A included 62 patients with glycated hemoglobin (HbA₁c)≤6.5% (48 mmol/mol) and group B 81 patients with HbA₁c>6.5%. In vitro transfer of lipids was determined by 1 h incubation of a donor nanoemulsion containing radioactively labeled unesterified and esterified cholesterol, phospholipids and triglycerides with whole plasma followed by chemical precipitation and radioactive counting in the supernatant (HDL). LDL and HDL cholesterol were similar in Group A and B, but group B had higher triglycerides (2.31±1.30 vs. 1.58±0.61 mmol/l, P<0.0001) and total and non-HDL unesterified cholesterol (36.3±7.8 vs. 33.9±5.9 mmol/l, P<0,05; 30.6±7.9 vs. 27.6±6.2 mmol/l, P<0,05; respectively) than group A and a non-significant trend to increased apolipoprotein B (103±20 vs. 97±20 mg/dl, P=0.08). 36 patients with the highest, ≥8.0% (64 mmol/mol), HbA₁c also showed non-significant trend of elevated non-esterified fatty acids (NEFA) compared to 37 with lowest, ≤6.0% (42 mmol/mol), HbA₁c (P=0.08). Patients with higher NEFA had higher triglycerides than those with lower NEFA levels (P<0.01).Transfers of all lipids from nanoemulsion to HDL and lipid composition of HDL were equal in both groups. For the first time it was shown that in addition to triglycerides, unesterified cholesterol is also a marker of poor glycemic control. In vitro HDL lipid transfers, an important aspect of HDL metabolism, were not related with the glycemic control.