Metabolic complications of antiretroviral therapy in HIV-infected patients include insulin resistance, diabetes mellitus, dyslipidaemia and lipodystrophy syndrome. Metabolic syndrome is an aggregation of central obesity with glucose and lipid metabolism alterations that confers an increased risk of cardiovascular disease, which reproduces the antiretroviral-associated metabolic and morphological abnormalities. In this study, we report the prevalence of diabetes mellitus, hyperinsulinaemia and metabolic syndrome among 755 adult patients with HIV-1 infection referred to our outpatients unit. The prevalence of diabetes mellitus and metabolic syndrome was 4.5% and 9.1%, respectively. A longer exposure to antiretroviral therapy and a diagnosis of lipodystrophy syndrome were significantly associated with both metabolic disturbances.