AimsType 2 diabetes (T2D), a prevalent cardiovascular disease, is linked with cardiac arrhythmias such as atrial fibrillation (AF) and ventricular arrhythmia. This study evaluated T2D's impact on these arrhythmias in patients with obstructive hypertrophic cardiomyopathy (OHCM). Methods and materialsWe retrospectively analyzed the data of 75 patients with OHCM and T2D from two medical centers in China from 2011 to 2020. A propensity score-matched cohort of 150 patients without T2D was also analyzed. ResultsAltogether, 225 patients were included. The prevalence of supraventricular tachycardia (SVT), AF, and non-sustained ventricular tachycardia (NSVT) was higher in patients with HCM and T2D than in those without T2D. Multivariate logistic regression showed T2D as an independent risk factor for SVT (odds ratio [OR] = 1.90, 95% confidence interval [CI] = 1.01–3.58, P = 0.04), AF (OR = 2.68, 95% CI = 1.27–5.67, P = 0.01), and NSVT (OR = 2.18, 95% CI = 1.04–4.57, P = 0.04). Further analysis identified fasting glucose and glycosylated hemoglobin levels as independent risk factors for AF and NSVT in patients with T2D. ConclusionsT2D independently increases the risk of cardiac arrhythmias (SVT, AF, NSVT) in OHCM patients. Furthermore, fasting glucose and glycosylated hemoglobin levels independently heighten AF and NSVT risk in OHCM patients with T2D.