Effect of a low-glycemic index or a high-cereal fiber diet on type 2 diabetes: a randomized trial.
BACKGROUND
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.


METHODS
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.


METHODS
High-cereal fiber or low-glycemic index dietary advice.


METHODS
Absolute change in glycated hemoglobin A(1c) (HbA(1c)), with fasting blood glucose and cardiovascular disease risk factors as secondary measures.


RESULTS
In the intention-to-treat analysis, HbA(1c) decreased by -0.18% absolute HbA(1c) units (95% confidence interval [CI], -0.29% to -0.07%) in the high-cereal fiber diet compared with -0.50% absolute HbA(1c) 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 HbA(1c) concentration (r = 0.35, P < .001) and negatively to the increase in high-density lipoprotein cholesterol (r = -0.19, P = .009).


CONCLUSIONS
In patients with type 2 diabetes, 6-month treatment with a low-glycemic index diet resulted in moderately lower HbA(1c) levels compared with a high-cereal fiber diet. Trial Registration clinicaltrials.gov identifier: NCT00438698.
Jenkins
David J A
DJ
Clinical Nutrition and Risk Factor Modification Center, St Michael's Hospital, Toronto, Ontario, Canada.
Kendall
Cyril W C
CW
McKeown-Eyssen
Gail
G
Josse
Robert G
RG
Silverberg
Jay
J
Booth
Gillian L
GL
Vidgen
Edward
E
Josse
Andrea R
AR
Nguyen
Tri H
TH
Corrigan
Sorcha
S
Banach
Monica S
MS
Ares
Sophie
S
Mitchell
Sandy
S
Emam
Azadeh
A
Augustin
Livia S A
LS
Parker
Tina L
TL
Leiter
Lawrence A
LA
D000368:Aged; D001786:Blood Glucose; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003131:Combined Modality Therapy; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000178:diet therapy*; D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D002523:Edible Grain; D005260:Female; D006442:Glycated Hemoglobin; D038321:Glycemic Index; D006801:Humans; D000960:Hypolipidemic Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D006442:Glycated Hemoglobin; D000960:Hypolipidemic Agents