In normal metabolism, insulin is secreted from the beta cells of the pancreas in response to carbohydrates in the diet. One of the functions of insulin is allowing carbohydrates to have access to the mitochondria of cells where they are converted into fuel (ATP) that is used by cells to perform their normal functions.
Sometimes, however, that process doesn’t occur as efficiency as it was designed. Cells do not respond appropriately to the carbohydrate signal and excess insulin is required to allow them to enter the cells.
There are many reasons this dysfunction occurs. For example, normally insulin will link to a receptor on the surface of the cell to begin the process that allows carbohydrates to enter cells. If there is a lack of receptors, insulin will be inefficient in allowing cells to produce energy and all their functions will be impaired.
Figure 1 depicts the decrease number of insulin receptors in normal cells and insulin-resistant cells.