The effects of experimental diabetes on energy intake, patterns of nutrient selection, water intake, body weight and body composition were examined in male Sprague-Dawley rats given ground Purina Chow or a dietary self-selection regime. Following adaptation to dietary conditions, a portion of the animals in each diet group were made diabetic by the administration of 45 mg/kg streptozotocin (STZ). The remaining animals in each group served as vehicle-injected controls. STZ reliably produced diabetes in rats on both dietary regimes. Immediately after the induction of diabetes, rats on the self-selection regime increased carbohydrate and protein intakes and decreased fat intake. Approximately three weeks after STZ administration, diabetic rats reduced carbohydrate intake and increased fat intake. Diabetic animals in both diet groups were hyperphagic and polydipsic relative to non-diabetic controls. During the first three weeks following STZ injections, energy and water intakes of diabetic animals in the two dietary conditions were similar. However, after this initial period, energy and water intakes of diabetic rats given the self-selection regime were significantly lower than those of diabetic animals given Purina Chow.