: Table S2). Level of antidiabetic treatment was categorized into three levels based on the type and number of different antidiabetic drugs classes prescribed in the year prior to cohort entry: level 1, patients not prescribed an antidiabetic drug or treated with only one antidiabetic drug; level 2, patients treated with ≥ 2 different classes of non-insulin antidiabetic drugs; level 3, patients treated with ≥ 1 insulin either alone or in combination with other antidiabetic drugs.
2is versus DPP4is, with in-hospital death treated as a competing event . We also evaluated the proportional hazards assumptions using Schoenfeld residuals, which revealed no violations.In secondary analyses, we subclassified 2i to DPP4i to estimate the relative effect of each 2is and DPP4is using the Wald test for heterogeneity. We further stratified by the history of cardiovascular disease , history of heart failure, and the history of chronic kidney disease to examine whether the risk of adverse respiratory events associated with