Even when blood sugar was kept normal, giving insulin made the body’s stress system more active than when nothing was given — suggesting insulin itself, not just the experiment, triggered the response.

When healthy young men were given insulin without changing their blood sugar, their body’s stress response system kicked in more — their heart beat faster and blood pressure rose, likely because insulin triggered their nerves to release more adrenaline.

Giving a higher dose of insulin to healthy young men made their stress response even stronger than a lower dose — their blood pressure and heart activity rose more, showing that more insulin leads to more nerve activity, even if blood sugar stays the same.

Even though there was more adrenaline in the blood during insulin infusion, the body wasn’t clearing it out slower — meaning the increase was because the nerves were releasing more, not because the body was holding onto it.

When blood sugar was raised without insulin, the body’s stress system didn’t react — meaning high sugar by itself didn’t trigger the same nerve response as insulin did.