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Long-term Glucose Variability and Cognitive Function in Older Type 2 Diabetic Patients

Visit-to-visit glucose variability may play a key role in cognitive function in type 2 diabetic patients….

Previous studies have shown an association with hypoglycemic/hyperglycemic episodes and change in cognitive function in diabetic patients, however it remains uncertain whether long-term exposure to glucose variability prompts cognitive changes in diabetic patients. A recent study showed that elevated HbA1c and blood glucose levels and glucose variability had a negative associated with cognitive function in aged type 2 diabetes patients; However in that study, HbA1c accounted for <10% of the variability in cognition.

The purpose of this study is to evaluate whether long-term (visit-to-visit) glucose variability in type 2 diabetic patients affects cognitive function independently of mean glucose parameters. The study was designed as a cross-sectional study which included 68 patients with type 2 diabetes. These patients had no history of hypoglycemia, psychiatric conditions, or other medical illness. The patients visited the endocrinology outpatient clinic every 3 months to measure fasting blood glucose, postprandial glucose, and HbA1c values. The cognitive function test was performed with a psychologist in the morning to decrease short-term variation between blood glucose. Each patient was instructed to eat a regular meal and take their medication prior to the cognitive testing. Mini Mental State Examinations were conducted to assess overall cognitive function, Verbal Learning Tests were conducted to assess delayed recall and recognition, a Digit Span test was conducted to assess concentration and verbal memory, a Boston Naming Test was conducted to assess confrontational naming, a Rey complex Figure Copy Test was conducted to assess visual perception and memory, and a Controlled Oral Word Association Test was assess for semantic/phonemic fluency.

The results showed that the average age of participants was 70.9 years and the average follow up with the outpatient clinic was 4.8 years. The average fasting blood glucose was 132 mg/dl and the average postprandial was 199 mg/dl. The average HbA1c was 8.0%. Postprandial glucose levels were associated with the Mini Mental State Examination score and with low scores on the Rey complex Figure Copy Test. High HbA1c levels were associated with low Mini Mental State Examination score and Digit Span test.

The researchers concluded that glucose variability is correlated with a decline in cognition function.

Practice Pearls:

  • The current findings suggest that high glucose variability was associated with cognitive decline.
  • Glucose variability may be a contributor to cognitive decline in type 2 diabetic patient.
  • Further studies should investigate whether decreases in glycemic variability improve cognitive decline in this population.

Kim C, Sohn JH, Jang MU, et al. “Association between Visit-to-Visit Glucose Variability and Cognitive Function in Aged Type 2 Diabetic Patients: A Cross-Sectional Study.” PLoS ONE. 2015;10(7):e0132118.