Beneficial Effect of a Low Glycaemic Index Diet in Type 2 Diabetes

Authors

  • Dr T.M.S. Wolever,

    Corresponding author
    1. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    2. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
      Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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  • D.J.A. Jenkins,

    1. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    2. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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  • V. Vuksan,

    1. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    2. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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  • A.L. Jenkins,

    1. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    2. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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  • G.C. Buckley,

    1. Department of Clinical Biochemistry, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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  • G.S. Wong,

    1. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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  • R.G. Josse

    1. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
    2. Division of Endocrinology and Metabolism, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada M5S 1A8

Abstract

Low glycaemic index foods produce low blood glucose and insulin responses in normal subjects, and improve blood glucose control in Type 1 and well-controlled Type 2 diabetic patients. We studied the effects of a low glycaemic index diet in 15 Type 2 diabetic patients with a mean fasting blood glucose of 9.5 mmol I−1 using a randomized, crossover design. Patients were given pre-weighed diets (59% energy as carbohydrate, 21% fat, and 24g 1000-kcal−1 dietary fibre) for two 2-week periods, with a diet glycaemic index of 60 during one period and 87 during the other. On the low glycaemic index diet, the blood glucose response after a representative breakfast was 29% less than on the high glycaemic index diet (874 ± 108 (± SE) vs ± 204 ± 112 mmol min I−1; p < 0.001), the percentage reduction being almost identical to the 28% difference predicted from the meal glycaemic index values. After the 2-week low glycaemic index diet, fasting serum fructosamine and cholesterol levels were significantly less than after the high glycaemic index diet (3.17 ± 0.12 vs 3.28 ± 0.16 mmol I−1p < 0.05, and 5.5 ± 0.4 vs 5.9 ± 0.5 mmol I−1, p < 0.02, respectively. Urinary C-peptide excretion, as an index of insulin secretion, was 30% lower on the low than the high glycaemic index diet (2.05 ± 0.30 vs 2.93 ± 0.49 nmol mmol-creatinine−1; p < 0.02), urinary urea was reduced by 19% (347 ± 27 vs 402 ± 39 mmol 24-h−1; p < 0.025), consistent with enhanced colonic fermentation. These results suggest that low glycaemic index starchy foods may be beneficial in the treatment of Type 2 diabetes.

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