Diabetes contributes to cholesterol metabolism regardless of obesity.

OBJECTIVE: To investigate cholesterol metabolism in obesity with and without diabetes. RESEARCH DESIGN AND METHODS: We performed cross-sectional metabolic studies in obese individuals with and without type 2 diabetes. The study population consisted of 16 obese (BMI >30 kg/m(2)) diabetic subjects with a mean age of 52 +/- 2 years (SE) and 16 nondiabetic control subjects of similar age and weight. Cholesterol absorption efficiency was measured with peroral dual isotopes and cholesterol synthesis with sterol balance.
RESULTS: Serum total cholesterol did not differ between the groups, but LDL and HDL cholesterol were significantly lower and VLDL cholesterol and serum total and VLDL triglycerides were higher in the diabetic group than in the control group. Cholesterol absorption efficiency was 29 +/- 1% in diabetic subjects vs. 42 +/- 2% in the control subjects (P < 0.01). Cholesterol synthesis was higher (17 +/- 1 vs. 14 +/- 1 mg. kg(-1). day(-1); P < 0.05) and neutral sterol and bile acid excretion and cholesterol turnover tended to be higher in the diabetic group than in the control group. Blood glucose was positively related to cholesterol synthesis in the diabetic group (r = +0.663, P < 0.01) and in the control group (r = +0.590, P < 0.05), suggesting that the higher blood glucose level, the higher the cholesterol synthesis. In addition, blood glucose was significantly positively related to fecal neutral sterol excretion in both groups.
CONCLUSIONS: Cholesterol absorption efficiency was lower and cholesterol synthesis was higher in obese subjects with diabetes than in those without diabetes, suggesting that diabetes modulates cholesterol metabolism more than obesity alone.