REN and diabetes mellitus: Two clinical trials measuring capillary density with videomicroscopy in dorsal finger skin showed no difference between healthy and glucose-intolerant subjects[10] or patients with type 2 diabetes.[14] A possible explanation might be that the diabetic patients received a blocker of the renin-angiotensin system for hypertension.[14] It has been shown that especially drugs targeting the RAS ameliorate capillary rarefaction.[29] Alternatively, it has to be questioned whether videomicroscopy in the dorsal finger skin assesses the capillary bed that is predominantly damaged by diabetes.