There are 3 common myths about insulin. The first is that insulin raises blood pressure and causes dyslipidemia, and, as a consequence, may increase the risk of atherosclerosis. The second is that insulin aggravates insulin resistance. The third is that insulin therapy inevitably results in weight gain.
How did these myths come about? The history of these myths is interesting. Let’s talk first about the myth that insulin is atherogenic. A number of epidemiological studies going back to the 1970s and continuing even now demonstrated that the higher the circulating insulin levels, the higher the likelihood of coronary artery disease (CAD). Most of these studies were done in nondiabetic populations. There is no question that there is an association between insulin levels and CAD. But that’s because insulin is easy to measure, and so epidemiologists measure insulin, not insulin resistance, and may conclude erroneously that insulin is responsible for the increased CAD. One has to appreciate that the reason the insulin levels are high is that there is insulin resistance. The body’s compensatory mechanism to overcome the insulin resistance is to raise the circulating insulin level.
In healthy people who can compensate for the insulin resistance, you can have a higher insulin level and still have a normal glucose level. Hyperinsulinemia is a compensatory mechanism that is not itself responsible for the increased CAD. The culprit is the insulin resistance, not hyperinsulinemia. Insulin resistance leads to both high blood pressure and dyslipidemia. If you look at the mechanisms, the sequence of events becomes clear.