Aim: The conflicting relationships of serum omentin with inflammation markers and cardiometabolic disorders were investigated. Results & methods: Unselected 864 population-based middle-aged adults were cross-sectionally studied by sex-specific omentin tertiles. Men in the lowest omentin tertile (T1) had lower systolic blood pressure, HbA1c and glucose values and tended in T3 to higher lipoprotein(a) levels. Logistic regression analysis, adjusted for four covariates, revealed significant independent associations with the presence of hypertension and diabetes only in men. Sex-and age-adjusted odds ratio in gender combined for T2 & T3 versus T1 was 1.34 (95% CI: 1.00-1.79) for metabolic syndrome. Discussion & conclusion: The elicited adverse relationships of omentin-1 support the notion of oxidative stress-induced proinflammatory conversion of omentin, rendering loss of anti-inflammatory properties.