Carbohydrate-Induced Memory Impairment in Adults With Type 2 Diabetes

  1. Carol E. Greenwood, PHD12,
  2. Randall J. Kaplan, PHD12,
  3. Stacey Hebblethwaite, BSC12 and
  4. David J.A. Jenkins, MD, PHD13
  1. 1Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
  2. 2Kunin-Lunenfeld Applied Research Unit and Department of Food and Nutrition Services, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada
  3. 3Clinical Nutrition and Risk Modification Centre and Division of Endocrinology and Metabolism, St. Michael’s Hospital, Toronto, Ontario, Canada
  1. Address correspondence and reprint requests to Carol Greenwood, Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada M5S 3E2. E-mail: carol.greenwood{at}


OBJECTIVE—Memory impairment is observed in adults with type 2 diabetes. The focus of this study was to determine whether acute carbohydrate consumption contributes to or exacerbates memory dysfunction.

RESEARCH DESIGN AND METHODS—The impact of consuming 50 g of rapidly absorbed carbohydrate (one half bagel and white grape juice) at breakfast was examined in 19 adults with type 2 diabetes. Subjects (mean age 63 ± 9 years, mean BMI 26.1 ± 4.5 kg/m2) were tested, under fed and fasted conditions, on verbal declarative memory using both word list and paragraph recall tests (immediate and delayed [7-min] recall), Trails Test Part B as a measure of general brain function, and mood (subjectively monitoring global vigor and affect).

RESULTS—Under baseline (fasting) conditions, elevated blood HbA1c was negatively associated with immediate and delayed paragraph recall performance (R2 = 0.30; P = 0.024) and higher fasting blood glucose trended toward poorer word list recall (R2 = 0.09; P = 0.102). Carbohydrate ingestion influenced measures of delayed, but not immediate, recall in a time-dependent fashion (time × food) (word list, P = 0.046; paragraph, P = 0.044) such that delayed recall was improved at 15 min postingestion but was impaired at 30 min. Neither Trails Test scores (P = 0.17) nor mood (affect, P = 0.68 and vigor, P = 0.45) were influenced by food ingestion.

CONCLUSIONS—In adults with type 2 diabetes, poorer glycemic control is associated with lower performance on tests of declarative memory. Acute ingestion of high glycemic index carbohydrate foods further contributes to the underlying memory impairment.


  • A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

    • Accepted March 24, 2003.
    • Received December 3, 2002.
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