Thirty millilitres (30ml) of blood will be drawn during visit 1, and 73.5 ml during visit 2. Sixty millilitres (60ml) of blood will be drawn from the research participants during visits 3 to 5, and at visit 7. During visits 6 and 8, 67.5 mls of blood will be drawn.Blood will be drawn into vacutainer tubes containing either ethylenediaminetetraacetic acid (EDTA), lithium heparin, sodium fluoride, clot activator or a DPP-4 inhibitor cocktail.