Despite studies reporting a possible association between malignant otitis externa (MOE) and diabetes, there are no large-scale population-based empirical studies. This nationwide, population-based case-control study explored the association of MOE occurrence with previously diagnosed diabetes.Data were retrieved from Taiwan's National Health Insurance Research Database, 753 patients with MOE (cases) and 2 259 propensity score-matched patients without MOE (controls). Multiple logistic regressions were conducted to examine the association of MOE with previously diagnosed diabetes.In total, 728 (24.2%) out of 3 012 sample patients had diabetes prior to the index date. Chi-square test revealed a significant difference in diabetes prevalence among cases and controls (54.8% vs 13.9%,  < 0.001). Simple logistic regression showed the odds ratio for prior diabetes among cases versus controls was 7.50 (95% CI, 6.22~9.03). The adjusted odds ratio of prior diabetes for cases versus controls was 10.07 (95% CI, 8.15~12.44) after adjusting for patient demographics and medical co-morbidities.This study found an association between MOE and diabetes. One clinical practice implication of our study is that when a patient with diabetes complains of otalgia or otorrhea, and physical examination shows swelling of the ear canal or granulation growth, physicians should consider the possibility of MOE.