The aim of the study was to investigate the effects of regularly eating a moderate amount of sucrose (30 g/day) in 12 type 1 (insulin-dependent, IDDM) diabetic outpatients in fair blood glucose and lipid control. Two diets, each lasting two months, were compared in a randomized cross-over study. The former was a high-carbohydrate high-fiber diet for diabetic patients with Italian alimentary habits, the latter had the same composition except that 30 g of sucrose replaced 30 g of complex carbohydrates with high glycemic index (bread). The two diets contained equal amounts of carbohydrates, proteins and lipids; the only difference being the contribution of oligosaccharides to total carbohydrates (22% vs 34%) and cholesterol amount. During the control diet, glycosylated hemoglobin was substantially unchanged in both control and sucrose diet periods (control diet: 6.91 +/- 0.29 (SE) vs 6.80 +/- 0.25%; sucrose diet: 6.75 +/- 0.31 vs 6.91 +/- 0.36%). This was true also for fructosamine (control diet: 3.92 +/- 0.21 vs 3.76 +/- 0.18%; sucrose 3.50 +/- 0.14 vs 3.64 +/- 0.20 mmol/l). Circulating blood lipid levels, body weight and daily insulin dose did not show any significant variations during the study. Moderate amounts of sucrose may be allowed to IDDM patients with Italian alimentary habits without worsening diabetic control.