Based on the observation that some common foods containing the same type and the same amount of carbohydrates were capable of producing different glycemic responses in normal subjects and subjects with diabetes, the concept of the glycemic index was developed. The glycemic index classifies carbohydrate-containing foods according to the patient’s glycemic responses expressed as a percentage of a reference food such as bread. The different glycemic responses to foods containing the same amount of carbohydrates depend mainly, at least in normal subjects, on their different rates of absorption by the small intestine. A major factor affecting absorption by the gut is the type of carbohydrates: mono-or disaccharides versus polysaccharides, the proportion of amylose versus amylopectin composing the polysaccharides, and the presence or absence of soluble dietary fibers. It was hoped that the glycemic index concept would provide a better means of predicting the impact of carbohydrate-containing foods on the glycemic response and help in the dietary prescription for patients with diabetes. Unfortunately, few studies have been published on the use of low glycemic index diet on the glycemic control of type I diabetes. In fact, no long-term studies are available; only acute and short-term studies have been done. Eight acute studies have assessed the effect of low glycemic index versus high glycemic index diets in a total of 80 subjects with type I diabetes. Only one of eight studies showed a significant decrease in the postprandial plasma glucose rise with the meal. Only five studies have evaluated the short-term effect of a low glycemic index diet in 42 subjects with type I diabetes. The mean treatment duration was 4±0.7 weeks, and the mean reduction in glycemic index was 25.8%±5.5%; only one of the five studies showed a significant decrease in the fructosamine level after the low glycemic index diet. Overall, these studies suggest that the use of low glycemic index carbohydrate-containing foods does not have any advantage in the treatment of type I diabetes over the use of carbohydrate count or food exchanges. However, there is no contraindication to incorporating low glycemic index foods in the dietary treatment of type I diabetes.