The goal of the clinical management of type 1 and type 2 diabetes is to control metabolic abnormalities in order to prevent both acute (hyperglycemia, hypoglycemia) and long-term (retinopathy, nephropathy, neuropathy, cardiovascular disease [CVD]) complications without negatively affecting quality of life (1).Achieving and maintaining blood glucose (BG) levels as close to normal as possible is crucial for the prevention of long-term complications in both type 1 and type 2 diabetes; however, attaining stringent glycemic targets requires an intensive approach to management. Nutrition is of utmost importance in the intensive management of diabetes and is often described as the cornerstone of care.A major focus of nutritional management of diabetes is the improvement of glycemic control by balancing food intake with endogenous and/or exogenous insulin levels.
Several strategies to control the glycemic response to food, particularly those rich in carbohydrate, have been developed and investigated. These include carbohydrate counting, use of very low carbohydrate and starvation diets, artificial sweeteners, pharmacotherapy and inhibitors of carbohydrate absorption. One way to classify the glycemic response to various carbohydrate containing foods is the glycemic index (GI). This term was first coined by David Jenkins and colleagues to describe the extent to which BG rises after ingestion of 50 g of available carbohydrate in a test food compared with ingestion of an equivalent amount of carbohydrate in a reference food, usually glucose or white bread .Although the GI has made it easier to predict the glycemic response to carbohydrate-containing foods, the clinical utility of this concept continues to be questioned .There is also concern that people living with diabetes may misapply the GI . Although not currently endorsed by the American Diabetes Association (ADA) , use of the GI is advocated by the World Health Organization (WHO) and diabetes associations in Europe,Australia,South Africa and Canada . The use of the GI in practice, and the use of low-GI diets in particular, was advocated in a report prepared by the joint Food and Agriculture Organization (FAO)/WHO Expert Consultation Committee .The report highlights how the GI can be applied to mixed meals, or to entire diets, and favours its use in the management of individuals at high risk of developing diabetes and those with established diabetes .
In the management of type 1 and type 2 diabetes, glycemic control is assessed mainly by fasting and preprandial BG levels and by longer term indices such as glycosylated hemoglobin (A1C). However, postprandial glycemia should also be considered ,as there is evidence suggesting it may be an independent risk factor in the development of diabetes-related complications, including CVD . With respect to diet composition, both the amount and source of carbohydrate, as defined by the GI, are important factors influencing postprandial glycemia. Furthermore, a growing body of evidence, including data from epidemiological and clinical studies, has linked low-GI diets with improved outcomes such as a decreased risk of development of type 2 diabetes and improvements in both metabolic control and quality of life in individuals with established diabetes. However, debate continues as to how the GI can best be incorporated into everyday practice by healthcare professionals and into the daily lives of individuals with diabetes.
This technical review defines the concept of GI, reviews the relevant research, assesses the clinical utility or usefulness of the GI in the nutritional management of diabetes,and provides suggestions for how to integrate this concept into practice based on current knowledge.All relevant GI literature (studies, reviews, meta analyses, editorial commentaries) from 1980 to 2003 were examined.
