DPP4 and diabetes mellitus: Thus, we used propensity score matching and multivariable regression analysis incorporating markers of disease severity and other clinical covariates, including age, sex, BMI, smoking, Charlson score, comorbidities of malignancy, CKD, cardiovascular disease, pneumonia, COPD, use of anti-diabetes medications (i.e. DPP4 inhibitors, SGLT2 inhibitors and aGI), and insulin use (see also Supplementary Method).