Low Glycemic Index Diet Yields Improvements in Diabetic Youth

Dr. Tonja R. Nansel of the National Institute of Child Health and Human Development noted in comments that,  "As the participants all used a basal-bolus insulin regimen, and carbohydrate consumption was standardized, the findings suggest that a low glycemic index diet has utility for improving glycemic control to a clinically meaningful degree above that obtained by careful carbohydrate counting and contemporary insulin regimens."

Dr. Nansel and colleagues tested the effects of high glycemic index and low glycemic index meals using continuous blood glucose monitoring in 20 type 1 diabetics between 7 and 16 years old.

All participants used a basal-bolus insulin regimen, in which insulin dose was calculated based on amount of carbohydrate consumed, and a correction factor was applied based on blood sugar levels. The two diets were matched for calories and macronutrients (carbohydrate, protein, and fat).

Dr. Nansel reported, "When consuming the low glycemic index diet, blood glucose levels were in the target range of 70 to 180 mg/dL 66% of the time compared to 47% of the time when consuming the high glycemic index diet." "The difference was statistically significant."

When consuming the low glycemic index diet, study subjects also demonstrated significantly lower daytime mean blood glucose levels compared to the high glycemic index diet (137.6 versus 184.2 mg/dL). "They also showed significantly lower blood glucose area over 180 mg/dL, and lower high blood glucose index, a measure of blood glucose variability," Dr. Nansel said.

There were no marked differences between the two conditions in the blood glucose area under 70 mg/dL or the low blood glucose index. There were no significant differences between the two dietary conditions during the nighttime hours. "The absence of a difference in nighttime blood glucose parameters supports the understanding that a low glycemic index diet affects blood glucose through reduction of postprandial excursions," Dr. Nansel pointed out.

Blood glucose levels falling below 80 mg/dL were treated with 15 grams carbohydrate from juice. Treatment for blood glucose below 80 mg/dL occurred more frequently during the low glycemic index dietary condition (13 subjects) than the high glycemic index condition (8 subjects), the researchers found.

"Considering both the greater frequency of mild hypoglycemia that was observed and the greater actual amount of carbohydrate consumed per unit of insulin in the low glycemic index condition," Dr. Nansel pointed out that "it is plausible that a low glycemic index diet may reduce insulin dose requirement."

"Consistent consumption of a low glucose index diet may reduce insulin requirement while improving blood glucose control, but careful attention should be given to blood glucose monitoring and adjustment of insulin dose during transition to a low glycemic index diet," she added.