Effects at meal carbohydrate content on insulin requirements in type 1 diabetic patients treated intensively with the basal-bolus (ultralente-regular) insulin regimen

OBJECTIVE - In this study, we evaluated the effects of high- (55%) and low- (40%) carbohydrate diets on insulin requirements in nine type 1 diabetic s ubjects treated intensively with ultralente as basal insulin and regular in sulin as premeal insulin adjusted to the carbohydrate content of meals. RESEARCH DESIGN AND METHODS - Nine subjects were randomized in a crossover design to follow two diets consecutively for a period of 14 days each. A 3- day food diary was completed for each diet with the amount of carbohydrate in the mixed meals ranging from 21 to 188 g. Preprandial (5.9 vs. 6.1 mmol/ l) and postprandial (8 vs. 8.9 mmol/l) capillary glucose and fructosamine ( 310 vs. 316 mu mol/l) were comparable on both the low- and high-carbohydrat e diets. RESULTS - The assessment of meal carbohydrate content by the patients was e xcellent, with >85% of cases falling within 15% of computer-assisted evalua tion. When premeal regular insulin was prescribed in U/10 g of carbohydrate , the postprandial glycemic rise remained constant (2.4 +/- 2.8 mmol/l) ove r a wide range of carbohydrate ingested (21-188 g) and was not affected by the glycemic index, fiber, and caloric and lipidic content of the meals. Th is tight control was maintained during the low- and high-carbohydrate diet without any change in insulin requirements (breakfast, 1.5 vs. 1.5 U/10 g o f carbohydrate; lunch, 1.0 vs. 1.0; supper, 1.1 vs. 1.2) and in basal ultra lente insulin requirements (22.5 vs. 21.4 U/day). CONCLUSIONS - These results indicate that in type 1 diabetic subjects 1) in creasing the amount of carbohydrate intake does not influence glycemic cont rol if premeal regular insulin is adjusted to the carbohydrate content of t he meals; 2) algorithms based on U/10 g of carbohydrate are effective and s afe, whatever the amount of carbohydrate in the meal; 3) the glycemic index , fiber, and lipidic and caloric content of the meals do not affect premeal regular insulin requirements; 4) wide variations in carbohydrate intake do not modify basal (ultralente) insulin requirements; and, finally 5) the ul tralente-regular insulin regimen allows dissection between basal and prandi al insulin requirements, so that each can be adjusted accurately and indepe ndently.