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05/26/2009 - Articles

A low glycemic index has benefit in diabetes

By: Susan Aldridge, medical journalist, PhD


A low glycemic index diet did more for people with type 2 diabetes than a high fiber diet according to a new study. Those on low GI had lower blood glucose and a better cholesterol profile, both of which would improve heart health.


A low glycemic index diet has been compared to a high fiber diet for blood glucose control in diabetes and also for its impact on cholesterol profile. On these measure, the low GI approach comes out on top, which has implications for those managing diabetes through lifestyle measures.


Type 2 diabetes is associated with a higher risk of heart disease. And thus far, the administration of hypoglycemic medications has not been shown to reduce this risk, even though they may help manage blood glucose. The importance of diet in managing diabetes is well known but it is less clear which kind of diet is the most beneficial. The low glycemic index (low GI) which emphasizes foods such as legumes, nuts and pasta has gained popularity in recent years. Prior to that, high fiber was popular, with its emphasis on whole grains. A new study compares the two approaches.

What was done

Researchers at the University of Toronto randomly assigned 210 people with type 2 diabetes to either a low GI diet or a high fiber diet and measured their blood glucose (as glycated hemoglobin, the standard measure) and their cholesterol profile. In the low GI group, participants ate beans, peas, lentils, nuts, low GI breads like pumpernicket and cereals like oatbran. In the high fiber group, they consumed whole grain breads, cereals, brown rice, jacket potatoes and whole wheat bread. Both groups consumed five servings of vegetables and three servings of fruit a day.

What was found

Glycated hemoglobin went down by 0.50 percent in the low GI group and by 0.18 percent in the high fiber group - a small but clinically significant change. High density lipoprotein (HDL or 'good' cholesterol) went up by 1.7 mg/dL in the low GI group but down by 0.2 mg/dL in the high fiber group. And the ratio between HDL and LDL (low density lipoprotein or 'bad' cholesterol) was improved more in the low GI group than in the high fiber group.

What this study means

It looks as if a low GI diet can address the issues of both blood glucose control and cholesterol profile in type 2 diabetes - perhaps, therefore, going beyond what medication alone can do (which is control glucose). Therefore, the low GI approach is worth looking into when advising people with diabetes on the best type of diet to help manage their condition to reduce heart disease risk.


Effect of a low-glycemic index or a high-cereal fiber diet on type 2 diabetes DJ. Jenkins, CW. Kendall,  et al., Journal of the American Medical Association, December 17 2008, vol. 300, pp. 2742--2753

Created on: 01/02/2009
Reviewed on: 05/26/2009

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