Effect of repeated transforaminal epidural low-dose dexamethasone injections on glucose profiles of diabetic and non-diabetic patients with low back pain

Purpose: We aimed to investigate the effect of repeated transforaminal epidural low-dose dexamethasone injections on glucose profiles and pituitary-adrenal axis functions of diabetic and non-diabetic patients with low back pain. Methods: A total of 28 patients (ten diabetic [DM group] and 18 non-diabetic patients [non-DM group]) with low back pain were followed-up. Transforaminal epidural low-dose dexamethasone (1.65 mg) injections were repeated every 7–14 days for 8 weeks. Fasting blood sugar (FBS), hemoglobin A1c (HbA1c), morning plasma adrenocorticotropin (ACTH), and cortisol levels were measured at baseline and during the 8-week follow-up period. Results: There were no significant changes in FBS and HbA1c levels between baseline and 8-week follow-up period in both DM and non-DM groups (difference in FBS [95% confidence Interval, CI]: − 0.6 mg/dL [− 6.4, 5.1], p = 0.83 in the non-DM group, − 0.2 mg/dL [− 26.2, 25.8], p = 0.99 in the DM group; difference in HbA1c [95% CI] − 0.02% [− 0.1, 0.1], p = 0.69 in the non-DM group, 0.04% [− 0.3, 0.4], p = 0.79 in the DM group). There were no significant longitudinal changes in ACTH and cortisol levels (ACTH, p = 0.38 [baseline vs. 8 week], p = 0.58 [non-DM vs. DM]; cortisol, p = 0.52 [baseline vs. 8 week], p = 0.90 [non-DM vs. DM]). Conclusions: Repeated transforaminal epidural low-dose dexamethasone injections provided no significant elevations in blood glucose or suppression of the pituitary-adrenal axis for two months from the first injection in both diabetic and non-diabetic patients. Our results indicate the intermediate-term safety of repeated transforaminal epidural low-dose dexamethasone injections with regard to the effect on glucose profile and pituitary-adrenal axis functions.