Association of peripheral neuropathy with dementia in type 2 diabetes: a 5-year follow-up study using the national health insurance service-national health information database

Objective: To investigate whether the incidence of dementia is associated with diabetic peripheral neuropathy (DPN) in type 2 diabetes. Methods: Using the National Health Insurance Service-National Health Information Database, we calculated the incidence of various types of dementia according to type 2 diabetes with or without DPN by applying multivariate Cox regression analysis. Propensity score matching was performed to equalize each group by considering demographic characteristics and underlying conditions. Results: The incidence of various types of dementia was higher in patients with type 2 diabetes than in those without diabetes. The risk of developing dementia was higher in type 2 diabetes with DPN than in type 2 diabetes without DPN, irrespective of dementia type (all dementia: 1.53 vs. 2.1 vs. 1.4, P < 0.05, Alzheimer’s disease: 1.46 vs. 1.98 vs. 1.34, P < 0.05, vascular dementia: 1.86 vs. 2.75 vs. 1.66, P < 0.05, other dementia: 1.62 vs. 2.19 vs. 1.48, P < 0.05; all type 2 diabetes vs. type 2 diabetes with DPN vs. type 2 diabetes without DPN compared with non-diabetes). When sodium–glucose cotransporter-2 inhibitors (SGLT2Is) were used, the incidence of all dementia types was lower in patients with type 2 diabetes than in patients with type 2 diabetes who did not use SGLT2Is although the incidence showed more decreased trend when dipeptidyl peptidase IV inhibitor (DPPIVI) was combined (all dementia: 0.51–0.71, P < 0.05, Alzheimer’s disease: 0.78–0.80, P < 0.05, vascular dementia: 0.28–0.35, P < 0.05, other dementia: 0.2–0.70, P < 0.05; SGLT2Is user vs. neither SGLT2I nor DPPIVI). This pattern was also observed in patients with type 2 diabetes and DPN (all dementia: 0.32–0.56, P < 0.05, Alzheimer’s disease: 0.44–0.55, P < 0.05, vascular dementia: 0.33, P < 0.05, other dementia: 0.53, P < 0.05; SGLT2Is user vs. neither SGLT2I nor DPPIVI). Conclusions: More active diagnostic and prevention efforts are needed to address the risk of developing all forms of dementia, including vascular dementia, in patients with diabetes and DPN.