The study population is divided into 3 main groups, namely healthy controls, patients with diabetes type 2 (defined by American Diabetes Association's (ADA)) and patients with essential hypertension (the latter group is again divided into 3 subgroups: use of betablockers, angiotensin-converting enzyme (ACE)-inhibitors, angiotensin-receptor blockers (ARBs). Each main goup will consist of minimal 20 subjects.
In this interventional study the investigators ask the patient to come twice. One time they get capsules with real flavanols and the other time they get capsules with a placebo. The study will be double blinded so nor the investigators, nor the patients now at which investigation they get the real flavanols or the placebo.
Before and after the intake of these capsules, a few measurements will take place. These measurements will be compared on the one hand with the second investigation day (inter-patients and intra-patient) and on the other hand with the pre-intake measurements (intra-patient).
The different examinations are a Flow-mediated dilatation (FMD) test, blood pressure analysis and an exercise test.
The investigator who performs the FMD-test, followed a course and needed to pass an examination.
The blood pressure measurements will be continuously for 20 minutes to avoid to much bias.
