Because chronically elevated insulin levels and insulin resistance create this big fat storage problems, it is fair to say that hyperinsulinemia is toxic. Insulin toxicity increases the risk of atherosclerosis, cardiovascular diseases, and cancer [1,2,3,4].
It has been believed for a long time that glucose toxicity alone explains the increased risk of these conditions. This isn’t correct, insulin and other factors play a role too [5]. Case in point, controlling blood glucose levels by injecting insulin does not decrease the heart disease risk [6]. In fact, the opposite is true! Increased levels of insulin from injections further increase the net risk, despite lowering blood glucose sugars.