REN and kidney disorder: The coadministration of linagliptin, a DPP-4 inhibitor, drastically lowered albuminuria in patients with type 2 DM with renal disorders treated with renin-angiotensin-aldosterone system inhibitors, compared to the placebo (Groop et al., 2013), whereas alogliptin, another DPP-4 inhibitor, lowered albuminuria in patients with type 2 DM with early-stage nephropathy treated with angiotensin II receptor blockers (ARBs) (Fujita et al., 2014).