Insulin resistance is now being understood to be a major contributor to the onset of diabetes. While we know that glucose and glycosylated hemoglobin tests can be used to detect diabetes type I or II, many in the general public did not realize that higher glucose levels over a long period of time can create insulin resistance, thus setting the stage for the more serious forms of diabetes in the future.

What causes insulin resistance? One can point to current dietary habits and lack of exercise as the main contributors.

The body's cells need sugar in order to run their metabolic functions, from brain activity to running to the tasks of everyday living. Most of this sugar is presented to the cells through the bloodstream in the form of glucose. Glucose is produced by the liver from foods that are digested in the stomach and small intestine, and whose components end up in the liver for further processing. The liver produces enough glucose to power the then-needs of the body, while converting the rest of the sugars to fat for storage for later use.

The liver creates glucose from all food types, but is particularly stimulated by the carbohydrates, which are easier to convert to glucose with fewer byproducts (such as ketones, which are poisonous byproducts of the production of glucose from proteins).

Two general types of carbohydrates stimulate the liver in different ways: the 'simple' carbohydrates are converted much faster, and create large amounts of glucose relatively quickly after ingestion. Simple carbohydrates include all the things that we love to eat, but are regarded as junk food by the general media: unrefined sugars, such as those found in soft drinks and in our cereals, flour, such as that found in white bread and fried foods, and sugar found in candies like chocolate bars and 'energy bars,' which are mainly sugars.

The 'complex' carbohydrates, on the other hand, are converted to glucose at a much slower rate, which means that there is less of a glucose peak after one eats complex carbs. Complex carbohydrates include whole-wheat bread, spaghetti and other forms of pasta, and starches found in legumes like beans and potatoes. These are 'complex' because the liver must perform a series of chemical transformations before converting to the end-product, glucose.

Insulin resistance is the result of too much glucose circulating in the bloodstream for too long a time. The high levels of glucose stimulate the pancreas (more specifically, the Islets of Langerhans) to produce more insulin. And more insulin circulating in the bloodstream means that the cells are 'tired' of the excess of hormonal signal, and develop a resistance to the chemical.

Simple carbs, consumed in too great a quantity, are clear causes of this insulin overproduction. The other factor which contributes is inactivity. That is, the less one exercises, the less the body is able to absorb the glucose which is produced in such high quantities by the liver.

If, for example, one eats too many simple carbs, but goes out and runs for an hour, much of the insulin messages are accepted by the cells, glucose levels are reduced and insulin resistance doesn't occur.

Insulin resistance is therefore caused by two main factors: the types of food one eats, and the amount of exercise one does after eating. Both affect the level of insulin circulating in the bloodstream, and therefore can have an important influence over insulin resistance by the body's cells.