In this study we will examine if the insulin-induced microvascular effects will occur after a physiological stimulus (i.e. a oral glucose tolerance test). With that the physiological importance of the insulin-induced microvascular dilatation can be elucidated. In this study we hypothesize that oral glucose intake and consequently the endogenous induced hyperinsulinemia will lead to insulin-induced microvascular dilatation in healthy normotensive subjects. Furthermore, we suggest that the insulin-mediated microvascular dilatation, resulting from this physiological induced hyperinsulinemia, will be less in hypertensive and obese subjects compared to healthy controls.

Inclusion Criteria:

healthy normotensive subjects:

1. 18-60 years
2. Caucasian
3. Blood pressure <140/90 mmHg

obese normotensive subjects:

1. 18-60 years
2. Caucasian
3. Blood pressure <140/90 mmHg
4. BMI 30-38kg/m2

hypertensive subjects:

1. 18-60 years
2. Caucasian
3. Untreated hypertension >140/90mmHg.

Exclusion Criteria for healthy normotensive and hypertensive subjects:

1. Obesity (BMI>27kg/m2)
2. Cardiovascular disease (stroke, coronary artery disease, peripheral vascular disease, heart failure)
3. Diabetes mellitus according to the criteria of the ADA
4. Smoking
5. Alcohol use >4U/day
6. Use of medication (antihypertensive drugs, lipid lowering drugs, corticosteroids, NNSAIDs)
7. Pregnancy
8. Wearing contact lenses

for normotensive obese subjects:

1. Cardiovascular disease (stroke, coronary artery disease, peripheral vascular disease, heart failure)
2. Impaired glucose tolerance or diabetes mellitus according to the criteria of the ADA
3. Smoking
4. Alcohol use >4U/day
5. Use of medication (antihypertensive drugs, lipid lowering drugs, corticosteroids, NNSAIDs)
6. Pregnancy
7. Wearing contact lenses