INTRODUCTIONDiabetes mellitus is a heterogeneous metabolic disorder characterized by the common feature of chronic hyperglycaemia with disturbance of carbohydrate, fat and protein metabolism. 1 The increasing prevalence of diabetes over the world has become an important public health problem. As population is increasing, getting older, more obese and sedentary, the number of individuals with diabetes is also steeply rising.As of 2010, there were approximately 285 million people diagnosed with diabetes mellitus compared to around 30 million in 1985.2,3 Developing countries like India and China contribute much to the diabetic load of the world. 4Of the two types, Type-II diabetes is more common (90-95% of all cases) than type 1 and has increased markedly since 1960 in parallel with obesity.4 Type-II Diabetes Mellitus is a non-autoimmune, polygenic disease condition in which there is impaired insulin effectiveness (insulin resistance) and abnormal glucose homeostasis.This form generally manifests in mid-life or beyond with a mean age of about 45 years.1 Risk factors include age over 45 years, a positive family history, physical inactivity, low fibre diet, people with impaired glucose ABSTRACT Background: To evaluate the impact of type-II diabetes mellitus on cognitive function and to assess the factors associated with impaired function. Methods: This prospective study compared 100 type-II diabetic people attending the diabetic clinic of Tirunelveli Medical College Hospital with another 100 membered control group. The study group was selected randomly between the age group of 45-65 years. A neuro-cognitive assessment was done using Standardized Mini Mental State Examination (SMMSE), which is a simple and reliable screening test. This scale has 12 questions with time limits to assess orientation, memory, calculation, language, attention and construction. Magnitude and severity of cognitive decrement were analysed along with the possible factors affecting it. Results: Mean age of the study population was 54.6±7.24 years. Cognitive impairment was noted among 62 of cases and 48 of the control group, which means a 14% higher prevalence of cognitive impairment among the type 2 diabetics. The association of development of cognitive impairment and duration of diabetes mellitus was significant statistically (p value = 0.025443; p<0.05). Other demographic variables like gender, education and domicile were also seen to affect the results. Conclusions: Mild to moderate cognitive impairment was found significantly higher among the type-II diabetics than the non-diabetics. The cognitive impairment was found to be associated with the duration of diabetes. Hence the routine screening of cognition by SMMSE should be done in all type-II diabetic patients.