Abstract
Background: Studying the deleterious effects of Type 2 diabetes mellitus (T2DM) on cognition is gaining a lot of attention. Cognition is measured by the P300 component of event-related potentials (ERPs). Hence, we studied P300 in T2DM.

Aims and Objectives: This study was done with the objective to evaluate cognition of T2DM and also to evaluate factors associated with impaired cognition.

Materials and Methods: Thirty T2DM and 30 controls matched for their age and gender were selected considering inclusion and exclusion criteria. Cognitive assessment was done using mini-mental state examination, and subjects with scores higher than 25 (maximum score = 30) were included in the study. After ruling out hearing loss by pure tone audiometry, P300 recording was done on them using RMS EMG EP MARK II machine. The resulting data were statistically analyzed.

Results: P300 latencies (P < 0.001**) were longer in T2DM when compared with nondiabetics. P300 latencies showed significant positive correlation (r = 0.390*; P = 0.033) with T2DM duration. A significant difference was found in P300 latency between diabetic hypertensives (P = 0.003) and diabetic nonhypertensive, among diabetics with dyslipidemia (P = 0.047) and diabetics without dyslipidemia and between diabetic smokers (P < 0.001) and diabetic non-smokers.

Conclusion: Cognitive function of T2DM subjects should be examined on a regular basis using ERPs because there could be an association between T2DM duration and cognitive deterioration. T2DM, along with dyslipidemia, hypertension, and smoking, further aggravates the possibility of cognitive dysfunction. We conclude that dementia can be diagnosed by ERP P300 in the initial phase.

Key words: Event-related Potential; P300 Latency; Cognition; Type 2 Diabetes Mellitus; Mini-mental State Examination; Dementia