This was a case-comparison study to determine whether there was any association between non-insulin dependent diabetes mellitus (NIDDM) and cognitive impairment in subjects over the age of 65 years. Forty-eight non-insulin dependent diabetic males were compared with eighteen non-diabetic age & sex-matched controls. There was significantly higher cognitive impairment in the diabetic group compared to the control group when cognitive function was tested using the Mini-Mental State Examination (MMSE). However, after adjustment for confounding variables such as hypertension and cerebrovascular diseases there was no significant association between NIDDM per se and cognitive impairment. Other risk factors of cognitive impairment may be investigated.