The effects of elevated hemoglobin A1C on cognitive function in elderly type II diabetics in the Look Ahead study

Objective: Prolonged elevation of blood glucose levels in Type 2 Diabetes is related to a host of medical complications, most of which are mediated by micro and macro vascular damage. Importantly, diabetes is associated with accelerated cognitive decline and compromised brain health as the cerebral vasculature undergoes negative changes stemming from hyperglycemia. It is hypothesized that participants in the Look Ahead Brain study with higher HbA1c levels will exhibit worse performance on the cognitive measures, specifically on tasks assessing executive function. Methods: Data on participants from the Look Ahead study who also participated in the Look Ahead Brain ancillary study (n = 113) were analyzed. This included HbA1c levels at year 10 (the year that participants were administered the cognitive assessment), mean HbA1c, and change in HbA1c from baseline to year. In order to assess executive function the results on two cognitive tests, the Modified Stroop Color and Word Test and the Trail Making Test, were analyzed. Then, relationships between HbA1c and performance on each of these cognitive tasks were analyzed using two approaches. First, the cohort was split into two group based on HbA1c (HbA1c ≤ 7% vs HbA1c > 7%). The latter of the two groups represented participants will poorer glycemic control. Second, linear correlations were assessed using the full range of HbA1c values as a continuous variable.