We applaud van der Hooft et al1 in their study, demonstrating that the risk of new-onset atrial fibrillation (AF) was significantly higher for persons who received a corticosteroid prescription within 1 month before the index date than for those without (odds ratio [OR], 3.75; 95% confidence interval [CI], 2.38-5.87). The fact that only high-dose corticosteroid use was associated with an increased risk (OR, 6.07; 95% CI, 3.90-9.42), whereas low to intermediate dose corticosteroid use was not (OR, 1.42; 95% CI, 0.72-2.82), and that the association of AF with high-dose corticosteroid use was largely independent of the indication for corticosteroid therapy suggests that one possible explanation could be the sudden derangement in glucose metabolism resulting in fluctuating levels of glycemic control,2 which occurs with high-dose corticosteroid therapy. Indeed, previous reports have demonstrated that high glucose levels had a positive significant association with the risk of AF.3,4 Nearly a decade ago, Psaty et al,3 using step-wise models, demonstrated that high glucose levels were associated with AF. Of note, the Framingham study found that diabetes mellitus (DM) was a significant independent risk factor for AF with an OR of 1.4 and that blood pressures and glucose levels were more important predictors than the diagnoses of high blood pressure and DM.4 More recently, in a large-scale study involving a far larger number of patients over a long duration of study (10 years), Movahed et al5 showed that AF occurred in 43 674 patients with DM (14.9%) vs 57 077 subjects (10.3%) in the control group (P<.001). Atrial flutter occurred in 11 852 patients (4%) with DM vs 13 554 subjects (2.5%) in the control group (P<.001). In multivariant analysis, DM remained independently associated with atrial fibrillation (OR, 2.13; 95% CI, 2.10-2.16; P<.001) and flutter (OR, 2.20; 95% CI, 2.15-2.26; P<.001). Thus, deranged metabolic control resulting in high glucose levels may have to be monitored and aggressively treated with a short course of insulin therapy alongside concurrent high-dose corticosteroid treatment to prevent the occurrence of new-onset AF in such patients.