The incidence of end-stage renal disease in patients with diabetes mellitus is reportedly higher among blacks than among whites. This finding may be explained by the greater prevalence of diabetes among blacks. The relation of the type of diabetes to the risk of diabetic end-stage renal disease is largely unstudied. We addressed these issues in a study of all the black and white diabetic patients with end-stage renal disease (470 blacks and 861 whites) reported to the Michigan Kidney Registry who began treatment during 1974 through 1983. We also reviewed the medical records of a subpopulation of such patients (284 blacks and 310 whites) who were less than 65 years of age at the start of treatment for end-stage renal disease to determine what type of diabetes they had. In this study, we made use of national data on the prevalence of diabetes. We found that the incidence of diabetic end-stage renal disease was 2.6-fold higher (P less than or equal to 0.0001) among blacks after we adjusted for the higher prevalence of diabetes among blacks, with the excess risk occurring predominantly among blacks with non-insulin-dependent diabetes mellitus (NIDDM). Most black patients with diabetic end-stage renal disease had NIDDM (77 percent), whereas most white patients with diabetic end-stage renal disease had insulin-dependent diabetes mellitus (IDDM) (58 percent) (P less than or equal to 0.0005 for the difference between the races). For both races combined, the risk of diabetic end-stage renal disease during the 10-year period we studied was markedly greater for patients with IDDM (5.8 percent) than for those with NIDDM (0.5 percent). Our results indicate an increased risk of diabetic end-stage renal disease among blacks as compared with whites, particularly blacks with NIDDM. Although the risk of diabetic end-stage renal disease is higher in patients with IDDM, the majority of patients with diabetic end-stage renal disease in the population we studied had NIDDM.