When the lining of your blood vessels stops working properly, it makes diabetes and kidney disease much worse by damaging your blood vessels and increasing the chance of heart attacks, strokes, and circulation problems. This happens because the blood vessels can't relax properly, become stiff, and are more likely to form dangerous clots.

When the lining of blood vessels isn't working right and makes less of a substance that keeps vessels open, it can raise blood pressure — even if the heart's pumping and blood amount stay the same.

In healthy adults, insulin doesn't make blood vessels relax more when nitric oxide is already at work — meaning insulin probably doesn't improve blood flow by boosting the muscle's response to nitric oxide.

Uric acid messes with blood vessel relaxation in human cells more than it affects blood vessel tightening, which might explain how it harms blood flow.