Wikipedia
Insulin resistance (IR) is generally regarded to as a pathological condition in which cells fail to respond to the normal actions of the hormone insulin. The body produces insulin when glucose starts to be released into the bloodstream from the digestion of carbohydrates in the diet. Normally this insulin response triggers glucose being taken into body cells, to be used for energy, and inhibits the body from using fat as energy. The level of glucose in the blood decreases as a results, staying within the normal range even when a large amount of carbohydrates is consumed. When the body produces insulin under conditions of insulin resistance, the cells in the body are resistant to the insulin and are unable to use it as effectively, leading to high blood sugar. Beta cells in the pancreas subsequently increase their production of insulin, further contributing to a high blood insulin level. This often remains undetected and can contribute to a diagnosis of Type 2 diabetes or latent autoimmune diabetes of adults. Although this type of chronic insulin resistance is harmful, during acute illness it is actually a well-evolved protective mechanism. Recent investigations have revealed that insulin resistance helps to conserve the brain's glucose supply by preventing muscles from taking up excessive glucose. Insulin resistance should even be strengthened under harsh metabolic conditions such as pregnancy, during which the expanding fetal brain demands more glucose.