High Glycemic Index Linked to Type II Diabetes

The rising incidence of type 2 diabetes in the United States is fueling research into dietary influences of this debilitating disease. The current dietary recommendations (per the American Diabetic Association) for diabetics do not take into account so called "good" and "bad" carbohydrates. Carbohydrates can be divided according to the glycemic index (GI) which reflects the blood glucose response to consumption of carbohydrate containing foods. This scale is endorsed in many other developed nations, including Canada, Australia and most European countries. A study published recently in the American Journal of Clinical Nutrition (2005;82(3):647-552) revealed how glycemic index is linked to predictors of type 2 diabetes.

In this study, over 2000 American subjects aged 70-79 were recruited. They completed dietary assessments and measurements of blood glucose metabolism and body composition were obtained. The results showed that higher dietary GI was associated with higher 2 hour postprandial glucose and fasting insulin levels and lower thigh intramuscular fat in men. In women, the only association noted was higher 2 hour postprandial glucose with higher dietary GI. These findings confirm some prior work showing higher GI is linked to poor glucose metabolism. However, the observation that high dietary GI is associated with lower thigh fat is contradictory to previous research and may reflect some selection bias (subjects with diabetes and serious illness were excluded from the study).

This study highlights the importance of specific dietary choices in the prevention of type 2 diabetes. Not all carbohydrates are created equal, as many people are learning, and increasingly integrative health care providers are recommending lower glycemic index foods i.e. <55 (on a scale where table sugar is 100). Lower glycemic index foods include most vegetables (except corn, peas, beets, potatoes and pumpkin), oatmeal and many fruits. Higher glycemic index foods that should be avoided include any packaged food containing added sweeteners, watermelon, grapes, dried fruits, and refined grain products.