DPP4 and chronic obstructive pulmonary disease: 30-dDp, 30-day deceased patients; 30-dSp, 30-day survived patients; SD, standard deviation; CV, coefficient of variation; HbA1c, glycosylated haemoglobin; CKD, chronic kidney disease; TIA, transient ischemic attack; PAD, peripheral arterial disease; COPD, chronic obstructive pulmonary disease; T2DM, type 2 diabetes mellitus; DPP-4is, dipeptidyl peptidase 4 inhibitors; GLP-1 RAs, glucagon-like peptide 1 receptor agonists; SGLT-2is, sodium-glucose co-transporter 2 inhibitors