Using validated clinical tests and standardized controls, we measured hand function in diabetic subjects. Fifteen diabetic patients (median age 48 years), all having used insulin for a minimum of 5 years, were randomly selected from inpatient and outpatient services of an academic medical center. Testing was done on an outpatient basis. The three hand function tests used were the Purdue Pegboard, O'Connor Tweezer Dexterity, and Smith Hand Function. A symptom questionnaire was also included in the study. Function was significantly decreased in the diabetic group, and the decrease was out of proportion to their own subjective pretest assessments. These findings may have implications for occupational performance as well as activities of daily living.