Glycemic variability's impact on painful diabetic peripheral neuropathy in type 2 diabetes patients

Hyperglycemia in type 2 diabetes leads to diabetic peripheral neuropathy (DPN) and neuropathic pain, yet the association between glycemic variability and painful DPN remains insufficiently evidenced. To address this, we conducted a prospective longitudinal cohort study involving adult type 2 diabetes patients at a medical center. DPN was identified using the Michigan Neuropathy Screening Instrument (MNSI), and neuropathic pain was assessed with the Taiwan version of the Douleur Neuropathique 4 (DN4-T) questionnaire. At baseline in 2013, all participants were free of DPN and were re-evaluated in 2019 for the development of painful DPN. We measured visit-to-visit glycemic fluctuations using the coefficient of variation (CV) of fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c). Patients were stratified into tertiles according to their FPG-CV and HbA1c-CV. Among the 622 participants, 267 developed DPN during the six-year follow-up. Following matching of age and sex, 210 patients without DPN and 210 with DPN (including 26 with neuropathic pain) were identified. Our findings revealed a significant association between high FPG-CV and painful DPN, with the highest tertile showing an adjusted odds ratio of 2.82 (95% confidence interval 1.04-7.64) compared to the lowest tertile. On the contrary, HbA1c-CV did not show a significant association with the risk of painful DPN. Our study indicates that higher FPG-CV is associated with an increased risk of painful DPN, supporting the role of glycemic variability in the development of painful DPN.