Twelve outpatients with type II diabetes mellitus and mild clinical signs and history of cardiac failure were studied to assess the effects of ibopamine on glucose and lipid metabolism. For the assessment of cardiac failure a clinical score was computed, based on the evidence of dyspnea and ankle oedema. The patients were randomly allocated to ibopamine 100 mg t.i.d. or placebo in a double-blind cross-over 3 weeks design. Daily plasma glucose profile, glycaemia and plasma insulin during glucose tolerance test, serum C-peptide, lactacidemia, free fatty acids, triglycerides, urinary glucose, diuresis and clinical evaluation were the studied parameters. During the study, a clinically favourable trend for ibopamine was observed, as far as cardiac failure was concerned. No significant differences were found between ibopamine and placebo in any of the metabolic parameters. No change in diet or in the previous dosage of the antidiabetic drugs occurred during the study in any patient. We conclude that ibopamine 100 mg t.i.d. does not affect metabolic control and lipid pattern in type II diabetic patients, therefore representing a safe tool for the treatment of chronic heart failure in these patients.