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.

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 badly damaged kidneys and a salty diet, giving insulin for a month boosts kidney filtering power without affecting key blood pressure hormones, suggesting insulin helps kidneys adapt on its own.

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.

Giving rats insulin for a week while keeping their blood sugar normal doesn't change their blood pressure.