Non-invasive cardiac studies using systolic time intervals were performed on 89 diabetic Nigerians and 45 non-diabetic controls, to investigate possible preclinical abnormality of left ventricular function. There was no significant difference in the pre-ejection period to left ventricular ejection time ratio (PEP/LVET) between the patients and controls: 0.373 +/- 0.011 vs 0.365 +/- 0.013 (P = 0.688). Patients at higher risk for developing significant vascular disease i.e. those with peripheral vascular insufficiency, those in higher socio-economic class and those with disease duration of 10 or more years had the highest mean values of PEP/LVET (0.403, 0.403 and 0.412 respectively). However, these values did not reach a level of significance. There was no correlation between PEP/LVET and age, body mass index, duration of diabetes, total or HDL cholesterol and the HDL to total cholesterol ratio. Because recent reports have related diabetic cardiomyopathy to angiopathic disease in diabetes, these results suggest that Nigerian patients, who like most other black African diabetics show little susceptibility to severe vascular complications of diabetes may enjoy some protection from a preclinical abnormality of left ventricular function as well.