Introduction: Diabetic patients have an increased risk of developing dementia and cognitive impairments. DM related factors such as macrovascular and microvascular complications, glucose toxicity, hyperinsulinemia have been suggested to be involved cognitive impairment even in prediabetic stage. Our aim is to establish the relationship between insulin resistance and cognitive impairment and the effect of poorly controlled diabetes on cognitive impairment.
Research design and methods: Twenty prediabetic patients who were evaluated using a standard OGTT, 40 patients with T2DM and twenty non-diabetic healthy controls aged between 40 and 65 were included in this study. Forty patient with T2DM divided into two groups; well- controlled (A1c<7.5) and poorly controlled (A1c> 7.5) based on their HbA1c. All factors that might affect cognitive function excluded from the study. We assesed neuropsychological profile of these groups and compared with twenty non-diabetic, healthy controls. All patients and healthy controls matched for sex ratio and level of education. Attention & working memory, psychomotor speed, verbal memory, visuospatial memory and executive function were tested.
Results: Statistically significant differences between the patients with poorly controlled diabetes mellitus in Verbal Memory Process Test (P value < 0.05). In Trail Making Test part B diabetic patients showed significantly lower performances than prediabetics and controls. And in Wisconsin Card Sorting Test perseveration all three patients groups performed significantly worse (P value < 0.05) than controls.
Conclusion: T2DM causes early brain ageing and declines cognitive functions even in prediabetic stage. Chronic hyperglycemia and vascular complications in poorly controlled T2DM worsen cognitive impairments.