Chronic vagus nerve stimulation for drug-resistant epilepsy influences fasting blood glucose concentration

Abstract

Background Cervical vagus nerve stimulation (VNS) has been widely accepted as adjunctive therapy for drug-resistant epilepsy and major depression. Its effects on glycemic control in humans were however poorly understood. The aim of our study was to investigate the potential effects of VNS on fasting blood glucose in patients with drug-resistant epilepsy.Methods Patients with drug-resistant epilepsy who had received VNS implants at the same hospital in a randomized, controlled trial were retrospectively studied. Effects on fasting blood glucose, weight, body mass index and blood pressure were evaluated at 4, 8 and 12 months of follow-up.Results 32 subjects (11 females/21males, 19±9 years, body mass index 22.2±4.0 kg/m 2 ) completed 12-month follow-up. At the 4 months, there were no significant changes in fasting blood glucose concentrations from baseline to follow-up in both Sham-VNS (4.89±0.54 vs. 4.56±0.54 mmol/L, p=0.101) and VNS (4.80±0.54 vs. 4.50±0.56 mmol/L, p=0.117) groups. However, after 8 (4.90±0.42 mmol/L, p=0.001) and 12 (4.86±0.40 mmol/L, p=0.002) months of VNS, fasting blood glucose levels significantly increased compared to baseline values (4.52±0.54 mmol/L). Changes in fasting blood glucose concentrations at both 8 (R 2 =0.502, p<0.001) and 12 (R 2 =0.572, p<0.001) months were negatively correlated with baseline fasting blood glucose levels.Conclusions Our study suggests that chronic cervical VNS elevates fasting blood glucose levels with commonly used stimulation parameters in patients with epilepsy.Trial registration: VNSRE, NCT02378792. Registered 4 March 2015 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02378792