“Hemodynamically, angiotensin II (Ang II) has a relatively greater vasoconstrictive effect on efferent than on afferent arterioles. In addition, Ang II decreases the glomerular ultrafiltration coefficient. These combined effects result in increased intraglomerular capillary pressures. Angiotensin II increases the uptake and decreases the egress of circulating macromolecules in the glomerular mesangium and fosters mesangial cell mitogenesis. Thus, inhibition of Ang II generation may explain why angiotensin converting enzyme (ACE) inhibitors may be effective in arresting or slowing the progression of renal failure in experimental animals and in man.” From Journal of Hypertension
The following Video doesn’t do a good job when it talks about pressure already in the kidneys in diabetics.