Diabetes Mellitus and Acute Facial Palsy: A Nationwide Population-Based Study

Introduction: Acute facial palsy, characterized by sudden hemifacial weakness, significantly impacts an individual's quality of life. Despite several predisposing factors identified for acute facial palsy, the specific relationship between diabetes mellitus (DM) and acute facial palsy has not been comprehensively explored in recent studies. The aim of the study was to assess the risk of acute facial palsy in patients with DM using a nationwide population sample cohort. Methods: DM cohort and non-DM cohort were built using the Korean National Health Insurance Service-Sample Cohort which represents the entire population of the Republic of Korea from January 2002 to December 2019. The DM cohort comprised 92,872 patients with a record of medication and a diagnosis of DM. Individuals who had facial palsy before the diagnosis of DM were excluded. A comparison cohort comprised 1,012,021 individuals without DM matched sociodemographically in a 1:4 ratio. The incidence of Bell's palsy (BP) and Ramsay Hunt syndrome (RHS) were evaluated in both cohorts. The risk factors for acute facial palsy were also assessed. Results: Among the 92,868 patients in the DM cohort, the incidence rate (IR) of BP and RHS were 31.42 (confidence interval [CI], 30.24-32.63) and 4.58 per 10,000 person-years (CI, 4.14-5.05), respectively. Among the 371,392 individuals in the non-DM cohort, the IR of BP was 22.11 per 10,000 person-years (CI, 21.62-22.59) and the IR of RHS was 2.85 per 10,000 person-years (CI, 2.68-3.02). IR ratios for BP and RHS were 1.42 (CI, 1.36-1.48) and 1.61 (CI, 1.43-1.80). In multivariate analysis, DM (hazard ratio [HR] 1.428), age (HR 1.008), and high comorbidity score (HR 1.051) were associated with increased risk of BP, and male (HR 0.803) and living in metropolis (HR 0.966) decreased the risk of BP. And DM (HR 1.615), high comorbidity score (HR 1.078), and living in metropolis (HR 1.201) were associated with increased risk for RHS. Conclusion: This study suggests that patients with DM had an increased risk of acute facial palsy including BP and RHS.