To evaluate the current outcome of patients hospitalized with diabetic hyperosmolar state (DHS), we retrospectively studied 135 patients admitted to two general hospitals over an 11-year period. Mortality was 17%. Patients who died had a mean age of 77 years, compared to 68 years for the survivors (P = 0.008). They were also more likely to be nursing home residents (48 versus 23%, P = 0.01). Additionally, mean serum osmolality was significantly higher among those who died (383 versus 358 mosm/L, P less than 0.0001) as was blood urea nitrogen (81.3 versus 62.3 mg/dl, P = 0.006) and sodium (148 versus 137.4 mEq/L, P less than 0.001). However, mean glucose level and anion gap were similar among patients who died and patients who survived (1068 versus 1092 mg%; 23 versus 24 mEq/L, respectively). The presence of a chronic disease or an acute comorbid illness was not associated with mortality. Diminished physiologic reserve, attendant comorbidity, or functional disability may explain the effect of age and nursing home residence. High osmolality may indicate a greater water deficit and a more advanced stage of DHS at the time of diagnosis.