Acute effects of weight reduction on cholesterol metabolism in obese type 2 diabetes

Background: Weight reduction in obese type 2 diabetes increases the absorption efficiency of cholesterol and serum plant sterol levels from baseline. However, ther is no information on the effects of acute restriction of calories and lack of dietary cholesterol and plant sterols on serum cholesterol precursor and plant sterols and on cholesterol metabolism. Thus, 10 obese (BMI>30 kg/m(2)) type 2 diabetes subjects consumed very low energy diet virtually free of cholesterol, cholestanol and plant sterols for 3 months. Methods: Serum sterols were measured with gas-liquid chromatography. Results: Body weight was reduced by 15.5+/-1.7 kg (p<0.001), serum cholesterol by 21+/-3%, triglycerides 45+/-5%, glucose 23+/-3%, insulin 59+/-5% and HbAlc by 8+/-2%, whereas serum sex hormone binding globulin increase by 108+/-25% (p<0.05-0.001 for all). Serum desmosterol and lathosteol to cholesterol ratios (indicators of cholesterol synthesis) were significantly decreased by 20% suggesting that cholesterol synthesis was suppressed. Serum squalene ratio was unchanged. Despite lack of dietary plant sterols and cholestanol, serum campesterol and sitosterol ratios (indicators of cholesterol absorption efficiency) only extended to decrease, whereas serum cholestanol ratio, also an absorption indicator, was increased by 33 +/-3% (p<0.001), and ratios to campesterol and sitosterol were increased by 60% and 31% , suggesting that sterol absorption efficiency might have been increased and their turnover reduced. Conclusions: In obese type 2 diabetes, restriction of calories and dietary sterols improved markedly control of diabetes, decreased serum cholesterol precursor sterols suggesting that cholesterol synthesis was decrease, but only tended to decrease serum values of plant sterols probably due to their release from the adipose tissues associated with their impaired turnover.