Cognitive dysfunction in type 2 diabetes mellitus is associated with decrease in psychomotor speed, frontal lobe/executive function, verbal memory, processing speed, complex motor functioning, working memory, immediate recall. Although, type 2 diabetes is associated with several other vascular risk factors of dementia, diabetes itself has been implicated as an independent risk factor for cognitive impairment and dementia. The design was a prospective observation study to assess the cognitive function of diabetic patients treated with various classes of oral hypoglycemic with or without co-morbidities in various hospitals in Nilgiris and various tertiary health centers, Coimbatore. 400 patients were screened out of which 325 patients fulfilled the inclusion and exclusion criteria. The present study showed the patients taking dipeptidyl peptidase-4 inhibitors along with metformin showed a better global cognitive score than patients taking alpha glucosidase inhibitors, thiazolidinediones or sulphonylureas along with metformin.