Effects of 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 subjects treated intensively with ultralente as basal insulin and regular insulin 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 mumol/l) were comparable on both the low- and high-carbohydrate diets.

RESULTS

The assessment of meal carbohydrate content by the patients was excellent, with > 85% of cases falling within 15% of computer-assisted evaluation. When premeal regular insulin was prescribed in U/10 g of carbohydrate, the postprandial glycemic rise remained constant (2.4 +/- 2.8 mmol/l) over 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. This 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 of carbohydrate; lunch, 1.0 vs. 1.0; supper, 1.1 vs. 1.2) and in basal ultralente insulin requirements (22.5 vs. 21.4 U/day).

CONCLUSIONS

These results indicate that in type 1 diabetic subjects 1) increasing the amount of carbohydrate intake does not influence glycemic control if premeal regular insulin is adjusted to the carbohydrate content of the meals; 2) algorithms based on U/10 g of carbohydrate are effective and safe, 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 ultralente-regular insulin regimen allows dissection between basal and prandial insulin requirements, so that each can be adjusted accurately and independently.