Although the medical expenditures for the treatment of acute glycemic and chronic complications of diabetes are well documented, little is known about the costs of treating general medical conditions among persons with diabetes. Accordingly, data from the 1991 National Hospital Discharge Survey and the 1987 National Medical Expenditure Survey were used to estimate the risk of hospitalization for general medical conditions among middle-aged (45-64 yr) and elderly (> or = 65 yr) persons with diabetes and the associated in-patient expenditures attributable to diabetes in the United States. In 1991, there were 371,814 hospitalizations of middle-aged persons with diabetes and 712,725 hospitalizations of elderly persons with diabetes for treatment of general medical conditions. Both middle-aged and elderly persons with diabetes remained hospitalized longer than their nondiabetic peers (8.1 vs. 6.3 days and 10.1 vs. 8.9 days, respectively). Compared to their nondiabetic peers, middle-aged persons with diabetes were at greatest risk of hospitalization for peritonitis/intestinal abscess [relative risk, 13.1; 95% confidence interval (CI), 12.5-13.8] and respiratory failure (relative risk, 5.0; 95% CI, 4.9-5.1) and elderly persons with diabetes were at greatest risk of hospitalization for liver diseases (relative risk, 3.0; 95% CI, 2.9-3.0) and septicemia (relative risk, 2.8; 95% CI, 2.8-2.9). In-patient expenditures for the treatment of general medical conditions attributable to diabetes were estimated at +4.12 billion, nearly twice the in-patient expenditures incurred for the treatment of chronic complications of diabetes. These results demonstrate the disproportionate resources devoted to treating patients with diabetes for conditions that are neither acute glycemic nor chronic complications of diabetes.