Carbohydrates Can Induce Memory Impairment in Type 2 Diabetes

The degree of glycemic control is related to cognitive performance in adults with type 2 diabetes.

Because 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.

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).

The results showed that 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 x 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.

In summary, results from this study demonstrate that the degree of glycemic control is related to cognitive performance in adults with type 2 diabetes. Additionally, consumption of rapidly absorbed carbohydrate foods, providing as little as 50 g of available carbohydrate, can produce memory deficits. Whereas postprandial hyperglycemia and/or hyperinsulinemia may be associated with these deficits, further research is required to uncover the metabolic events leading to cognitive impairment.
Diabetes Care, July 2003