Correlation between Peripheral Neuropathy and Cognitive Factors in Type 2 Diabetic Patients

Diabetes is a well-known risk factor for dementia and cognitive impairment. Diabetic polyneuropathy (DPN) is the most prevalent microvascular complication in type 2 diabetes mellitus (T2DM) patients. The purpose of this study was to evaluate the relation between diabetic peripheral polyneuropathy and cognitive factors in T2DM patients. Retrospective chart review of type 2 diabetic patients with results of a nerve conduction study (NCS) and a neurocognitive study. A total of 19 patients were included. DPN was defined using data from a nerve conduction study: a score of less than 24 in the Korean version of the Mini-Mental State Examination (K-MMSE) was considered as an indicator of cognitive impairment (CI). The mean age of the 19 patients was 71.6±5.0 years. The mean duration of diabetes was 8.4±9.1 years, and the mean HbA1c level was 8.1±1.8%. DPN was present in 7 of the 19 patients. Based on the K-MMSE score, CI was diagnosed in eight patients. The mean K-MMSE scores and the prevalence of CI was not different between the groups with and without DPN. There was no significant difference in DPN prevalence between the groups with and without CI. Education was significantly correlated with cognitive factors. Only the digit span-forward among the cognitive factors showed a significant negative correlation with nerve conduction velocity. In conclusion, the longer education period was associated with higher cognitive function and no significant correlation was observed between diabetic peripheral neuropathy and cognitive dysfunction in type 2 diabetic patients. Further prospective research is needed in the future.