Cognition in the early stage of type 2 Diabetes Mellitus

Abstract

Objective Type 2 diabetes is known to be associated with decrements in memory and executive functions, and information processing speed. It is less clear, however, at which stage of diabetes these cognitive decrements develop and how they progress over time. This study investigated cognitive functioning of patients with recently screen detected type 2 diabetes mellitus, thus providing insight in the nature and severity of cognitive decrements in the early stage of the disease. Possible risk factors were also addressed.

Research Design and Methods 183 diabetes patients from a previously established study cohort and 69 control subjects were included. A full neuropsychological assessment, addressing six cognitive domains, was taken from each participant. Raw test scores were standardized into z-scores per domain and compared between the groups. Possible risk factors for cognitive decrements were examined with multivariate linear regression.

Results Relative to the control group mean z-scores were between 0.01 and 0.2 lower in the diabetic group across all domains, but after adjustment for differences in IQ between patients and controls only memory performance was significantly reduced (mean difference -.15 (95% CI -.28/-.03). A history of macrovascular disease and current smoking were significant determinants of slower information processing speed in patients with diabetes.

Conclusions This study shows that modest cognitive decrements are already present at the early stage of type 2 diabetes. A history of macrovascular disease and smoking are significant risk factors for some early decrements.