Diabetic nephropathy is associated with an increased familial risk of stroke.

OBJECTIVE: To test the hypothesis that genetic susceptibility to diabetic nephropathy is associated with an increased familial risk of vascular disease, we have examined the causes and rates of death of parents of individuals with type 1 diabetes complicated by diabetic nephropathy compared with the causes and rates of death of parents of control subjects with diabetes uncomplicated by nephropathy. RESEARCH DESIGN AND METHODS: Individuals with at least a 14-year duration of type 1 diabetes complicated by diabetic nephropathy were identified and matched for age, sex, and duration of diabetes to control subjects. A total of 118 patients and 118 matched control subjects were identified and approached to obtain information on parental age and cause of death. For parents who had died, the cause of death was ascertained from the death certificate. RESULTS: Kaplan-Meier curves showed that parents of subjects with nephropathy (PN) had reduced survival compared with parents of diabetic subjects without nephropathy (PC) (log rank test P < 0.05). There was an excess of all vascular deaths and, in particular, strokes in the parents of subjects with nephropathy (PN: 20 of 103 deaths, 19% vs. PC: 3 of 66 deaths, 4%; Fisher's exact test P < 0.01). CONCLUSIONS: Parents of diabetic patients with nephropathy have reduced survival. This seems to be largely explained by an increase in vascular deaths and, in particular, a four-fold increase in the number of strokes. This supports the hypothesis that a common hereditary risk factor predisposes to both vascular death and diabetic renal disease.