This study investigated whether unrefined or refined carbohydrate diets have any effect on metabolic control and on insulin requirement in near-normoglycaemic Type 1 (insulin-dependent) diabetic out-patients on continuous subcutaneous insulin infusion therapy. Two females and 8 males (aged 27 +/- 9 years; diabetes duration 13 +/- 8 years; duration of insulin pump therapy 22 +/- 5 months; means +/- SD) participated in a randomised cross-over study with two 6-week periods on self-selected refined and unrefined carbohydrate diets respectively. As a result, energy intake differed between the experimental diets (2372 +/- 669 kcal/day on unrefined diet vs 2757 +/- 654 kcal/day on refined diet, p = 0.04), as did the fibre intake (18 +/- 5 g/day with the refined carbohydrate diet vs 35 +/- 13 g/day with the unrefined carbohydrate diet, p = 0.02). The composition of nutrients was approximately 40% carbohydrate, 45% fat, and 13% protein with both diets. Body weight, HbA1c, daily mean blood glucose (7.2 +/- 0.6 mmol/l) and serum lipids remained virtually unchanged during the entire study. Insulin requirement varied between 40.1 +/- 7.9 U/day with the unrefined carbohydrate diet, and 42.5 +/- 10.1 U/day with the refined carbohydrate diet (NS). Thus, neither the refined nor the unrefined carbohydrate diet affected insulin requirement and metabolic control in these near-normoglycaemic, normolipaemic, non-obese, insulin-pump-treated Type 1 diabetic patients.