This study investigated the relationship between compliance with a prescribed diabetic diet and metabolic control of insulin-dependent diabetes mellitus (IDDM). The study sought to determine the degree to which patients translated food exchange prescriptions into appropriate food choices and to identify correlations between metabolic control (as measured by glycosylated hemoglobin level) and compliance with prescribed food exchanges, body mass index (BMI), and intake of energy and fat. Subjects were 40 inpatients and 29 outpatients aged 4 to 18 years with IDDM. Records of the inpatients' food selections for 3 days and 3-day food records collected from the outpatients (or their parents) were analyzed. For all 69 subjects, the mean daily deviation from the prescribed food exchanges was 23.8%, which indicates that subjects added or deleted approximately one of four prescribed exchanges. Records of actual food intake revealed that both patient groups had greater mean energy intakes than had been prescribed: 196 additional kcal for inpatients and 372 additional kcal for outpatients; fat sources accounted for 92% and 68% of the greater energy intake, respectively. No correlation was found between glycosylated hemoglobin level and BMI, energy intake, or fat intake.