DPP4 and systemic inflammatory response syndrome: DKA, diabetic ketoacidosis; DM, diabetes mellitus; DPP-4, dipeptidyl peptidase 4; GLP-1, glucagon-like peptide-1; HHS, hyperosmolar hyperglycemic state; CI, confidence interval; OR, odds ratio; SGLT2, sodium-glucose cotransporter-2; SIRS, systemic inflammatory response syndrome