Risk Factors of Hyperglycemia After Nerve Blockade with Dexamethasone in Non-Diabetes Mellitus Patients: A Cohort Study

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BACKGROUND: Glucocorticoids (GCs) are expected to inhibit the synthesis and release of proinflammatory cytokines, which induces local pain. Serious side effects or complications are considered rare with single-dose GC use. However, the amount of systemic absorption and the side effects induced by local GC injections are not well understood. OBJECTIVES: We measured the changes in glucose levels after single-does dexamethasone injection with nerve blockade using a continuous glucose monitoring system (CGMS) in non-diabetes mellitus (DM) patients and investigated the risk factors for hyperglycemia. STUDY DESIGN: This is a cohort study. SETTING: This study was conducted at Gifu University Hospital in Japan. METHODS: Forty-six non-DM patients who underwent elective lumbar or sacral nerve root pulsed radiofrequency or lumbar medial branch of the posterior primary rami conventional radiofrequency with dexamethasone (0.1 mg/kg) were analyzed. The patients underwent monitoring of their interstitial glucose using a CGMS. Hyperglycemia was defined as a blood glucose level ≥ 200 mg/dL. The area under the curve (AUC) where the blood glucose level was over 200 mg/dL was calculated and analyzed. The risk factors of hyperglycemia were determined using an applied ordinal regression model analysis with the AUC as the objective variable and 4 factors (age, body mass index, glucose level just before GC injection, and glycosylated hemoglobin) as explanatory variables. The blood glucose levels were predicted by a nonlinear regression model. RESULTS: The AUC and maximum glucose level were higher on the first day than after the second day. None of the 4 factors were predictors of hyperglycemia. The glucose level before the procedure was associated with the predicted blood glucose level on the first day (P = 0.042). However, the 95% upper confidence limit of the maximum predicted blood glucose level was less than the safety margin. The predicted blood glucose levels returned to the usual level after the second day. LIMITATIONS: First, GCs are metabolized by cytochrome p450 3A4, and it is possible that the inhibition of this pathway decreases the clearance of GCs. Some of our patients were taking medications that influence this cytochrome pathway. Second, we cannot eliminate the possibility of stress-induced hyperglycemia. Finally, we were unable to record the exact meal timing and calories the patients had consumed. CONCLUSIONS: The blood glucose levels were higher than usual on the first day following a local dexamethasone injection, but the levels were not critical in most cases. Because we cannot predict which patients will develop hyperglycemia, we must determine whether or not GCs can be safely administered and inform patients about potential complications. KEY WORDS: Glucocorticoids, hyperglycemia, nerve blockade, non-diabetes mellitus patients