Impact of steroid treatment for Bell's palsy on Glycemic control in patients with type 2 diabetes mellitus

Introduction: Corticosteroids are the primary treatment for Bell's palsy, but use in patients with type 2 diabetes mellitus (T2DM) is often limited by hyperglycemia concerns. This study assessed steroid-associated glycemic outcomes in diabetic Bell's palsy patients. Methods: This retrospective cohort study used the TriNetX Research Network to identify patients diagnosed with Bell's palsy from 2010 to 2024. Patients were stratified by T2DM status and receipt of systemic corticosteroids within 10 days of diagnosis. Propensity score matching was performed on age, sex, race, ethnicity, diabetes medications, and comorbidities. The primary outcome was the most recent glucose within 1–30 days post-diagnosis. Secondary outcomes were the most recent HbA1c within 1–6 months post-diagnosis and rates of diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS) within 3 months. Results: Among 6268 patients with Bell's palsy and T2DM, steroid-treated patients had higher glucose within 1–30 days post-diagnosis (162.4 vs. 152.4 mg/dL; P < 0.001). HbA1c within 1–6 months did not differ significantly (7.24% vs. 7.20%; P = 0.43). DKA rates did not differ significantly (1.10% vs. 0.84%; P = 0.32), and HHS occurred at a higher rate in steroid-treated T2DM patients (1.82% vs. 0.57%; P < 0.001; number needed to harm = 80). Conclusion: Corticosteroids for Bell's palsy in T2DM are associated with a small absolute increase in acute glucose and HHS risk, while HbA1c and DKA rates were not significantly different. As a hypothesis-generating study, prospective data are needed before definitive recommendations can be made; however, these results may support emergency clinicians in initiating timely steroid therapy with appropriate glucose monitoring at discharge.