Hyperinsulinemia is a marker for several disease, and carbohydrate ingestion causes the release of insulin, but high carbohydrate ingestion does not cause hyperinsulinemia. The reason that the, "if x=y and y=z, therefore x=z" argument doesn't work is because the problem is the insulin receptor. We are dealing with a biological organism that is extremely complex. There are more variables than meets the eye, and controlled scientific analysis of the situation reveals that a high complex carbohydrate diet lowers insulin levels. Regular aerobic exercise also enhances insulin receptor sensitivity and is protective against the development of atherosclerotic disease.
Insulin promotes anabolic (storage) processes and inhibits catabolic (breakdown) ones. Thus, it signals a "fed state" and instructs the body to store fuels for use later. Insulin promotes uptake and storage of glucose in muscle and fat cells. In the muscle, glycogen is built from glucose molecules. In fat cells, the glucose is used to make fat. Once assimilated into fatty acids the glucose is trapped (i.e. animals cannot break down fatty acids to yield glucose). However, the fatty acids can be exported into the blood stream for use as fuel. Additionally, insulin inhibits the production of glucose by the liver. The body has a series of checks and balances to all of it's processes and insulin is no exception. There are counter-regulatory hormones (glucagon, catecholamines, and cortisol) which give the opposite signal to insulin.
If one looks at epidemiological data, the traditional diet of many third world countries consists of high complex carbohydrate content, very low fat, and high fiber. Athersosclerotic disease was virtually unheard of until the introduction of the high fat Western diet. There are many published studies which show that starting insulin resistant individuals on a high carbohydrate / low fat diet reduces hyperinsulinemia, hypertension, and hyperlipidemia. For example in a study published in the American Journal of Cardiology (Am J Cardiol 1992;69:440-444), diabetic patients (NIDDM), insulin resistant patients, and normal controls were started a 3 week program of diet ( 75 - 80% carbohydrate, 10-15% protein, and<10% fat) and exercise. in all there were statistically significant reductions in blood pressure, insulin levels, and triglycerides. additionally, high-carbohydrate / high-fiber diets have been shown to lower cholesterol and may reduce the risk of colon cancer.
Unfortunately, that is the best straightforward answer I have. There is no exact reason why it is or isn’t happening but if you want to check out some articles or studies that I used, let me know I will send em.