Low glycemic index diet boosts glucose control and HDL in diabetics

Medical Tribune February 2009 P10
David Brill

Following a low glycemic index (GI) diet can improve blood sugar control and raise HDL-cholesterol levels in type 2 diabetics, according to a recent study in the Journal of the American Medical Association.

Researchers from St. Michael’s Hospital and the University of Toronto, Canada, randomized 210 patients to follow either a low-GI diet or a high-cereal fiber diet for 6 months.

At the end of the study, HbA1C had decreased by 0.5 percentage points among those in the low-GI diet group, compared to just 0.18 percentage points in those following the high-cereal fiber diet. When comparing the two diets the relative change in HbA1C was 0.33 percent (P<0.001). p="0.005).">JAMA 2008 Dec 17;300(23):2742-53]

Participants in the trial all had HbA1C values between 6.5 and 8 percent at baseline screening, and had not had their diabetes medications changed within the preceding 3 months.

The European Society of Cardiology (ESC) said in a statement that the study supports current recommendations on lifestyle advice for the control of diabetes.

“Treatment of type 2 diabetes should always be initiated with structured lifestyle advice. Results from the JAMA study suggest that such advice may be as effective as some drug interventions,” said ESC spokesman for diabetes and cardiovascular disease Professor Lars Ryden of the Karolinska University Hospital, Sweden.

“The JAMA study also shows that a well-balanced diet will improve not only blood glucose tolerance but also blood lipid levels, which are of great importance in decreasing cardiovascular complications. If drugs are still needed in these circumstances, their dose and number may be lower,” he added.

The usefulness of GI as a dietary guide has proved controversial in the past. The index gives a measure of the extent to which certain foods affect the body’s glucose levels, but critics have questioned the methodology used to determine the values. [Diabetes Care 2003 Aug;26(8):2466-8]

The American Diabetes Association does not specifically advocate the low-GI diet, but notes on its website that it “may be helpful in ‘fine-tuning’ blood glucose management” and could provide additional benefits for those individuals who wish to pay close attention to their dietary choices.

Another recent trial, involving 162 type 2 diabetics, found that following a low-GI diet for a year did not improve glycemic control compared to a high-GI diet, although it did reduce postprandial glucose and C-reactive protein levels. [Am J Clin Nutr 2008 Jan;87(1):114-25]