ObjectiveTo investigate whether nondipping and diabetes are independently related to metabolic risk profile and prevalence of target organ damage in a population setting.MethodsA population-based cohort of 70-year-old men (n= 1057) was examined with 24-h ambulatory blood pressure monitoring, euglycemic hyperinsulinemic clamp and lipid and glucose determinations. We defined nondipping as a night–day systolic blood pressure ratio⩾1 (n= 66). Urinary albumin excretion rate and echocardiographically determined left ventricular geometry were used as indices of target organ damage.ResultsNondipping was not related to hypertension, but diabetes was more common in nondippers (26%) than in dippers (14%,P<0.05). Nondiabetic nondippers did not differ from dippers regarding insulin sensitivity, plasma glucose or lipids. However, nondipping in diabetic subjects was associated with the most pronounced impairments in body mass index, serum triglycerides and fasting plasma glucose. Measures of target organ damage did not differ between nondippers and dippers in the whole population, but an interaction (P<0.05) between nondipping and diabetes contributed to an increased left ventricular mass in diabetic nondippers. The urinary albumin excretion rate was independently related to diabetes.ConclusionsIn this population study, an interaction between diabetes and nondipping was demonstrated regarding fasting plasma glucose, lipid levels and left ventricular mass, indicating that nondipping is a marker of risk in diabetic subjects. However, in the nondiabetic majority of the population, nondipping was not associated with either metabolic disturbances or target organ damage.