The association of insulin responses and insulin sensitivity with cognition in adults with pre-diabetes: The Diabetes Prevention Program Outcomes Study

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.