pdf: Effect of a Low–Glycemic Index or a High–Cereal Fiber Diet on Type 2 Diabetes: A Randomized Trial

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Effect of a Low–Glycemic Index or a High–Cereal Fiber Diet on Type 2

Diabetes: A Randomized Trial

J. A. , MD

JAMA. 2008;300(23):2742-2753.

http://jama.ama-assn.org/cgi/reprint/300/23/2742

Context Clinical trials using antihyperglycemic medications to improve

glycemic control have not demonstrated the anticipated cardiovascular

benefits. Low–glycemic index diets may improve both glycemic control and

cardiovascular risk factors for patients with type 2 diabetes but debate

over their effectiveness continues due to trial limitations.

Objective To test the effects of low–glycemic index diets on glycemic

control and cardiovascular risk factors in patients with type 2 diabetes.

Design, Setting, and Participants A randomized, parallel study design

at a Canadian university hospital research center of 210 participants

with type 2 diabetes treated with antihyperglycemic medications who were

recruited by newspaper advertisement and randomly assigned to receive 1

of 2 diet treatments each for 6 months between September 16, 2004, and

May 22, 2007.

Intervention High–cereal fiber or low–glycemic index dietary advice.

Main Outcome Measures Absolute change in glycated hemoglobin A1c

(HbA1c), with fasting blood glucose and cardiovascular disease risk

factors as secondary measures.

Results In the intention-to-treat analysis, HbA1c decreased by –0.18%

absolute HbA1c units (95% confidence interval [CI], –0.29% to –0.07%) in

the high–cereal fiber diet compared with –0.50% absolute HbA1c units

(95% CI, –0.61% to –0.39%) in the low–glycemic index diet (P < .001).

There was also an increase of high-density lipoprotein cholesterol in

the low–glycemic index diet by 1.7 mg/dL (95% CI, 0.8-2.6 mg/dL)

compared with a decrease of high-density lipoprotein cholesterol by –0.2

mg/dL (95% CI, –0.9 to 0.5 mg/dL) in the high–cereal fiber diet (P =

..005). The reduction in dietary glycemic index related positively to the

reduction in HbA1c concentration (r = 0.35, P < .001) and negatively to

the increase in high-density lipoprotein cholesterol (r = –0.19, P = .009).

Conclusion In patients with type 2 diabetes, 6-month treatment with a

low–glycemic index diet resulted in moderately lower HbA1c levels

compared with a high–cereal fiber diet.

Trial Registration clinicaltrials.gov identifier: NCT00438698

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