ASSOCIATIONS OF FASTING BLOOD-GLUCOSE WITH CHOLESTEROL ABSORPTION ANDSYNTHESIS IN NONDIABETIC MIDDLE-AGED MEN

NIDDM and the metabolic syndrome are characterized by a low serum HDL cholesterol content and a high triglyceride level, whereas total and L DL cholesterol concentrations are not necessarily elevated, Variable r esults have been reported on cholesterol absorption, elimination, and synthesis in NIDDM, but no studies are available on subjects within th e normal range of blood glucose, From serum samples collected in 1985 from 203 nondiabetic men aged 51-66 years, we examined lipids, cholest erol precursors (reflecting cholesterol synthesis), and plant sterols and cholestanol (reflecting cholesterol absorption) in relation to fas ting blood glucose, The findings prompted us (in 1993) to further exam ine 11 men from the highest and lowest glucose thirds of 203 nondiabet ic men by additional dietary, serum, and fecal analyses for absorption , elimination, and synthesis of cholesterol and insulin sensitivity, I n 1985, blood glucose was significantly related to LDL apolipoprotein B (P = 0.05) but not to LDL cholesterol (P = 0.19). Significantly high er serum lathosterol and desmosterol-to-cholesterol proportions and lo wer plant sterol and cholestanol proportions in the highest rather tha n the lowest glucose thirds suggested that the subjects with high norm al blood glucose had decreased absorption and enhanced synthesis of ch olesterol, In 1993, men with the lowest glucose versus those with the highest glucose had a lower waist-to-hip ratio, plasma HbA(1c), fastin g and postload insulin and glucose values, and a higher insulin sensit ivity index, In agreement with tile 1985 non-cholesterol sterol data, direct analyses of cholesterol metabolism showed further higher choles terol absorption efficiency (P = 0.03) and serum plant sterol and chol estanol proportions (P < 0.001), Despite a slightly lower dietary chol esterol intake, cholesterol synthesis (P = 0.02) and serum lathosterol (P < 0.01) and desmosterol (P < 0.01) proportions were lowest in men with the lowest glucose third, We conclude that noncholesterol sterols in serum exhibits a long-lasting correlation with blood glucose level in a nondiabetic male population. Low intestinal absorption and high synthesis of cholesterol characterize men with high normal blood gluco se, Differences in cholesterol metabolism could be due to underlying i nsulin effects associated with obesity-like fat distribution and may t hus imply novel aspects in the metabolic interrelation between insulin and cholesterol in humans.