DPP4 and type 2 diabetes mellitus: Participants were taking various medications for their T2DM condition prior to and post-surgery, such as biguanides (55%), dipeptiyl-peptidase-4 (DPP-4) inhibitors (5%), sulphonylureas (5%) and, often, combined treatment with more than one diabetes medication, mainly biguanides combined with sulphonylureas (35%).