Insulin resistance and NAFLD may influence memory performance in obese patients with prediabetes or newly-diagnosed type 2 diabetes

Background and aims: Diabetes has consistently been shown to increase risk for cognitive decline. Cognitive deficits may occur at the very earliest stages of diabetes. We sought to estimate the determinants of memory function in a group of middle-aged obese subjects with prediabetes or newly-diagnosed type 2 diabetes mellitus. Methods and results: Sixty-two obese patients in treatment with metformin-with prediabetes (n = 41) or newly diagnosed T2DM (n = 21), were studied. Short- and long-term memory function was assessed through a neuropsychological assessment consisting of two tests and a composite domain z score was calculated. Cardiometabolic variables, such as abdominal MRI quantification of subcutaneous (SAT) and visceral (VAT) adipose tissue content, and of intra-hepatocellular lipid content, as well as insulin sensitivity (Matsuda Index, HOMA-IR) and beta cell performance (Beta Index), by multiple sampling, 8-point oral glucose tolerance test, were also evaluated. Age, non-alcoholic fatty liver disease (NAFLD), and lnHOMA-IR together explained 18% (R square) of the variance in memory domain. Including NAFLD increased the explained variance by 8% and including lnHOMA-IR by 9.1%, whereas the contribution of age and other factors was negligible. Conclusion: Preventing and managing insulin resistance in precocious and possibly earlier stages of diabetes might provide benefit in slowering down future cognitive decline.