This is a study of diabetes care and care outcomes for patients under the active care of private physicians. Randomly selected communities, physicians, and patients in Michigan were the subjects of this study. Data on the care practices of physicians and patients and care outcomes were collected from 1980 to 1981 and again in 1985 from eight communities, 61 physicians, and 261 patients. We found that the use of multiple injections of insulin and self-monitoring of blood glucose increased significantly, whereas hospitalizations for diabetes control decreased. The mean glycosylated hemoglobin values for this cohort of patients remained unchanged. The study results suggest that, for patients under the active care of community physicians, modern methods of diabetes care are being implemented, but the results of improved care do not show an impact on blood glucose control as measured by glycosylated hemoglobin values. The study was not designed to establish causation for the decrease in hospitalizations for these patients, but the data suggest that decreases may be more a function of changes in health-care policies rather than changes in patient health.