In normal persons the hormone insulin, which is made by the beta cells of the pancreas, regulates how much glucose is in the blood. When there is excess glucose in the blood, insulin stimulates cells to absorb enough glucose from the blood for the energy that they need. Insulin also stimulates the liver to absorb and store any glucose that is excess in blood. Insulin release is triggered after a meal when there is rise in blood glucose. When blood glucose levels fall, during exercise for example, insulin levels fall too.
Diabetes is a number of diseases that involve problems with the hormone insulin. Normally, the pancreas (an organ behind the stomach) releases insulin to help your body store and use the sugar and fat from the food you eat. Diabetes can occur when the pancreas produces very little or no insulin, or when the body does not respond appropriately to insulin. As yet, there is no cure. People with diabetes need to manage their disease to stay healthy.