Cognitive function in diabetic persons with peripheral neuropathy: a systematic review and meta-analysis

Objectives The aim of this study is to improve our knowledge of cognitive function in individuals with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus and with peripheral diabetic neuropathy (DPN). Methods A systematic review and meta-analysis was performed of publications included in PubMed, Scopus, PsycInfo and Web of Science databases until November 2021. The study was registered in PROSPERO (CRD42021229163). Results A total of 832 articles were identified, 19 of which were selected. The presence of DPN was associated with global cognitive impairment in the T1DM persons in two studies (p=0.046;p=0.03) and T2DM persons in four (p<0.00;p<0.02;p=0.011;p <= 0.05) . Differences in specific dimensions - memory, attention, and psychomotor speed - were found in both kinds of diabetes. The meta-analysis showed that the individuals with T2DM and DPN presented a lower mean cognitive performance than those without DPN (-1.0448;95%CI:-1.93%;-0.16%). Depression was associated with impaired cognitive function in these diabetic persons (p < 0.01). Conclusion The review reveals the great variability in instruments and methodologies, while providing results that support the presence of both global and domain-specific cognitive impairment in diabetic persons with DPN.