Due to failure to achieve control twenty-two patients with type 1 diabetes with symptomatic fluctuating blood glucose started on a diet limited to 70-90 g carbohydrates per day and were taught to match the insulin doses accordingly. The caloric requirements were covered by an increased intake of protein and fat. The purpose was to reduce the blood glucose fluctuations, the rate of hypoglycaemia and to improve HbA1c. After three and 12 months the rate of hypoglycaemia was significantly lowered from 2.9 +/- 2.0 to 0.2 +/- 0.3 and 0.5 +/- 0.5 episodes per week respectively. The HbAlc level was significantly lowered from 7.5 +/- 0.9% to 6.4 +/- 0.7% after three months and was still after 12 months 6.4 +/- 0.8%. The meal insulin requirements were reduced from 21.1 +/- 6.7 I.U./day to 12.7 +/- 3.5 I.U./day and 12.4 +/- 2.6 I.U./day after three and 12 months respectively. Furthermore the triglyceride level was significantly lowered whereas the levels for total cholesterol and HDL-cholesterol were unchanged. The present report shows that a 70-90 g carbohydrate diet is a feasible long-term alternative in the treatment of type 1 diabetes and leads to improved glycaemic control.