Objective: Dysglycemia is a significant risk factor for cognitive impairment. However, which pathophysiologic determinant(s) of dysglycemia, impaired insulin sensitivity (ISens) or the islet β-cell's response (IResp), contribute to poorer cognitive function, independent of dysglycemia is not established. Among 1052 adults with pre-diabetes from the Diabetes Prevention Program Outcomes Study (DPPOS), we investigated the relationship between IResp, ISens and cognitive function.
Research design and methods: IResp was estimated by the insulinogenic index (IGI; pmol/mmol) and ISens as 1/fasting insulin from repeated annual oral glucose tolerance tests. The mean IResp and mean ISens were calculated over approximately 12 years of follow-up. Verbal learning (Spanish-English Verbal Learning Test [SEVLT]) and executive function (Digital Symbol Substitution Test [DSST]) were assessed at the end of the follow-up period. Linear regression models were run for each cognitive outcome and were adjusted for dysglycemia and other factors.
Results: Higher IResp was associated with poorer performance on the DSST (-0.69 points per 100 unit increase in IGI, 95 % CI: -1.37, -0.01). ISens was not associated with DSST, nor were IResp or ISens associated with performance on the SEVLT.
Conclusions: These results suggest that a greater β-cell response in people at high risk for type 2 diabetes is associated with poorer executive function, independent of dysglycemia and ISens.
Keywords: Cognitive function; Insulin response; Pre-diabetes.
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