Fifty otherwise healthy patients with diabetes mellitus (37 males, 13 females; mean age: 53 +/- 10 years) of more than five year duration were compared with twenty six healthy age and sex matched controls. Detailed echocardiographic evaluation was done in all and systolic time intervals (STI) were measured. In diabetics, metabolic control and presence of microangiopathy were evaluated. PEP Index (patients: 146.23 +/- 17.04; controls: 121.99 +/- 5.15; p less than 0.001), PEP/LVET ratio (patients: 0.38 +/- 0.07; controls: 0.32 +/- 0.02; p less than 0.001), LVEF% (patients: 54.1 +/- 10.56; controls: 64.71 +/- 6.33; p less than 0.001), all were significantly altered in diabetics suggesting left ventricular dysfunction. The left ventricular posterior wall thickness (patients: 0.96 +/- 0.23 cm; controls: 0.85 +/- 0.12 cm; p less than 0.01) and interventricular septal thickness (patients: 1.2 +/- 0.24 cm; controls: 0.87 +/- 0.25 cm; p less than 0.001) in diastole were increased in diabetics. The PEPI correlated with day-to-day control but not with chronic glycemic control of diabetes mellitus. The PEP/LVET was significantly increased in patients with severe, as compared to those with none or mild microangiopathy (p less than 0.05). Thus, significant left ventricular dysfunction is evident in asymptomatic, otherwise healthy diabetics. Both metabolic control and microangiopathy may be responsible for the abnormalities.