Flavanols are natural substances who are frequently found in our nutrition. A lot of research has already been executed in the past to investigate what effects this flavanols could have in the human population. Based on these examinations, the investigators think and suggest that flavanols can have positive effects on the vascularly system, more specifically on the peripheral and cerebral blood vessels. The effects are only observed in a healthy populations, meanwhile patient populations like diabetes patients could really benefit from this. This is why the investigators will execute this study.

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.

Inclusion Criteria:

• men and woman, age 18 - 85 years old, diabetes type 2 and/or using 1 sort of blood pressure lowering medication (betablockers, calcium-antagonists, RAAS-inhibitors)

Exclusion Criteria:

• GENERAL: diabetes type 1, maturity-onset diabetes of youth (MODY), Latent Autoimmune Diabetes of the Adult (LADA), smokers, alcohol abuse, active cancer, chronic inflammatory disease
• MICROVASCULAR: retinopathy, diabetic/hypertensive nephropathy, peripheral sensoric neuropathy, autonomic neuropathy
• MACROVASCULAR: cardiovascular diseases, cerebrovascular diseases, active or chronic palindromic vasculitis
• MEDICATION with impact on endothelial function: NO-containing medication, phosphodiesterase Type 5 -inhibitors
• DISEASES who can affect the exercise test: chronic obstructive pulmonary disease (COPD) with Global Initiative for Chronic Obstructive Lung Disease (GLOD) -stages III and IV, Heart failure class 3 and 4, serious musculoskeletal diseases
• OTHER: pregnancy

The different capsules are separated into 2 boxes but both sorts of capsules have the same colour and size. They just have a different number marked on the white box. During the investigation day, the participant chooses an envelope marked with number 1 or number 2 leading to the decision of the box and thus the capsules they will get.