Introduction: Diabetes mellitus is one of the most common diseases whose prevalence is on the rise. It is believed that within the next 30 years, the number of diabetic patients will double in comparison to the year 2000.Aims: To Study the effect of impaired blood glucose level on cognitive functions. Materials and Methods: The present study was a Prospective cross-sectional study. This Study was conducted from Dec 2019 to June 2021 at Department of Physiology in association with department of Medicine at tertiary care hospital Result: In the present study, it was also seen that reduction in mean MMSE score in type2 DM subjects having duration above 5 years was significant when compared to those with duration less than 5 years. It shows that longer duration has an effect over cognitive function. Correlation coefficient between MMSE score and HbA1c was negative in this study, from which it is inferred that increase in HbA1c levels is associated with decrease in MMSE scores. Conclusion: We found that, Effective control needs proper diet, regular exercise, monitoring blood glucose by self and management of medications. A person’s cognitive skill to bring about the above mentioned needs is thus crucial for self-management of diabetes