Even though high insulin levels can briefly rev up the nervous system and make the kidneys hold onto salt, having high insulin for a long time doesn’t seem to raise blood pressure in people or animals — fat or thin — so it probably isn’t the main reason high blood pressure happens in obesity.

Some people and animals can have serious insulin problems without getting high blood pressure — even when they're obese — which means these insulin issues don't always cause high blood pressure.

In dogs with damaged kidneys and eating a lot of salt, pumping extra insulin into their blood for almost a month doesn’t raise their blood pressure — it stays normal, even though insulin levels go way up.

In dogs with most of their kidney removed, having high insulin levels didn’t make blood pressure go up any more when they were also given a blood-pressure-raising hormone — even though that hormone had already raised their blood pressure a bit on its own.

High insulin levels and insulin resistance are linked to high blood pressure in people, especially those who are overweight — but even some people at a healthy weight. This connection doesn’t show up in other types of high blood pressure, so it might be a key factor in the most common kind.

Insulin might not actually raise your blood pressure after all — recent studies haven't been able to prove that having too much insulin in your blood leads to high blood pressure.