Life expectancy is shorter in the subset of insulin-dependent diabetic (IDDM) patients who are susceptible to kidney disease. Familial factors may be important. In this study the prevalence of cardiovascular disease mortality and morbidity and of risk factors for cardiovascular disease was compared in the parents of 31 IDDM patients with elevated albumin excretion rate (AER > 45 microg/min; group A) with that of parents of 31 insulin-dependent diabetic patients with normoalbuminuria (AER < 20 microg/min; group B). The two diabetic patient groups were matched for age and duration of disease. Information on deceased parents was obtained from death certificates and clinical records and morbidity for cardiovascular disease was ascertained using the World Health Organization questionnaire and Minnesota coded ECG. Hyperlipidaemia was defined as serum cholesterol higher than 6 mmol/l and/or plasma triglycerides higher than 2.3 mmol/l and/or lipid lowering therapy; arterial hypertension as systolic blood pressure higher than 140 mmHg and/or diastolic blood pressure higher than 90 mmHg and/or antihypertensive treatment. The percentage of dead parents was similar in the two groups (26 vs 20% for parents of group A vs group B, respectively), but the parents of the diabetic patients with elevated AER had died at a younger age (58 +/- 10 vs 70 +/- 14 years; p < 0.05). Parents of diabetic patients with nephropathy had a more than three times greater frequency of combined mortality and morbidity for cardiovascular disease than that of the parents of diabetic patients without nephropathy (26 vs 8%; odds ratio 3.96, 95% CI 1.3 to 12.2; p < 0.02). Living parents of group A had a higher prevalence of arterial hypertension (42 vs 14% p < 0.01) and hyperlipidaemia (49 vs 26% p < 0.05) as well as higher levels of lipoprotein (a) [median (range) 27.2 (1-107) vs 15.6 (0.2-98) mg/dl; p < 0.05]. They also had reduced insulin sensitivity [insulin tolerance test: median (range) K(itt) index: 3.7 (0.7-6.2) vs 4.8 (0.7-6.7)% per min; p < 0.05]. In the families of IDDM patients with elevated AER there was a higher frequency of risk factors for cardiovascular disease as well as a predisposition to cardiovascular disease events. This may help explain, in part, the high prevalence of cardiovascular disease mortality and morbidity in those IDDM patients who develop nephropathy.