ACE and hypertensive disorder: Because hypertension is a common comorbidity in patients with T2DM and as little is known so far concerning possible interferences between antihypertensive drugs and CF actions especially in patients with diabetes mellitus, this study will additionally investigate possible influence of beta-blockers (BB), angiotensin converting enzyme inhibitor (ACEi), or angiotensin receptor blocker (ARB) in diabetic persons with arterial hypertension and non-diabetic persons with essential hypertension treated with these drugs.