- Current/chronic use of the following medication: thiazolidinedione (TZD), SU derivative, Glucagon like peptide 1 receptor agonist (GLP-1RA), (dipeptidyl peptidase 4 inhibitor) DPP-4I, SGLT-2 inhibitors, glucocorticoids, immune suppressants, antimicrobial agents, chemotherapeutics, antipsychotics, tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs). Subjects on diuretics will only be excluded when these drugs cannot be stopped for the duration of the study.