REN and diabetic kidney disease: Anti-hypertensive agents such as renin–angiotensin–aldosterone system (RAS) inhibitors, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin II receptor blockers (ARB) are used to treat DKD (Lewis et al., 1993; Brenner et al., 2001; Lewis et al., 2001; Yacoub and Campbell, 2015).