We investigated the associations between indices of cholesterol metabolism and features of the metabolic syndrome (MS) in the presence and absence of type-2 diabetes (T2DM).MethodsMen with the MS (N = 140) and 10 age- and sex-matched controls were recruited. Plasma lathosterol and campesterol were measured by gas chromatography–mass spectrometry, and their ratios to total cholesterol were used to estimate cholesterol metabolism.ResultsCompared with healthy controls, MS subjects had significantly higher lathosterol:cholesterol and lower campesterol:cholesterol ratios (p <0.05). In the MS subjects without T2DM (N = 82), campesterol:cholesterol ratio was positively associated with age and negatively associated with plasma triglyceride and insulin concentrations, while in MS subjects with T2DM (N = 58), the ratio was positively associated with age and adiponectin concentration, and negatively associated with BMI and insulin. Age and fasting insulin were independent predictors of campesterol:cholesterol ratio in MS subjects with T2DM. There was a significant negative association between plasma lathosterol:cholesterol with campesterol:cholesterol ratio (r = −0.436, p = 0.014) in MS subjects without T2DM but not in MS subjects with T2DM.ConclusionsCholesterol absorption efficiency was lower and cholesterol synthesis higher in MS subjects with or without T2DM compared with healthy individuals. Moreover, the reciprocal relationship between cholesterol synthesis and cholesterol absorption is lost in the presence of diabetes. ©2009 Elsevier Ireland Ltd. All rights reserved.