We determined serum adiponectin's role as a biomarker of metabolic syndrome (MetS), type 2 diabetes (DM) and hypertension among Turkish adults who have a high prevalence of MetS. Individuals with measured serum adiponectin concentrations, constituting a random sample of Turkish adults, were studied cross-sectionally. MetS was identified by criteria of the Adult Treatment Panel-III modified for male abdominal obesity. Median age of 547 men and 652 women was 54 years. MetS was identified in 46%. Linear regression analysis among nine variables revealed homeostatic model assessment (HOMA) index in both sexes and C-reactive protein (CRP) only in men as inversely associated covariates of adiponectin, and sex hormone-binding globulin (SHBG) as positive covariate in women. Age-adjusted sex-specifically dichotomized high vs. low adiponectin levels were significantly associated with DM (odds ratio (OR) 0.55, P = 0.01) and hypertension (OR 0.64, P = 0.012) in women, but not in men. Further adjustment for smoking status and presence of high/low BMI did not alter this sex-based relationship. As regards association with MetS, low adiponectin and high BMI interacted significantly in each sex. Yet adiponectin was associated only in men additively to the simultaneously adjusted five MetS components. We conclude that adiponectin concentrations, clearly linked to metabolic disorders, may diverge among sexes regarding protection against cardiometabolic risk through antiinflammatory or antioxidative function, Turkish men alone revealing significant dysfunction independent of obesity. This dysfunction may underlie also the association of adiponectin levels with MetS in men to be independent of the MetS components.