The beta cells of the islets of the pancreas recognise changes in blood sugar levels. The pancreas is located in the abdominal cavity behind the stomach. The pancreas makes intestinal digestive enzymes as well as different hormones.
When blood glucose level rises, the beta cells of the islets of Langerhans release insulin. Insulin is a hormone consisting of amino acids which lowers the blood glucose level and controls the fat and protein metabolisms.
When the blood sugar level drops, less insulin is released into the blood and the alpha cells of the islets release the hormone called glucagon which increases the blood sugar level. Glucagon releases the sugar stored in the liver into the blood stream.
Insulin is released in two different ways
In a healthy person, insulin is released by the beta cells of the pancreas in small bursts occurring every couple of minutes. This is called the basal insulin secretion. It controls the blood sugar level and metabolism, especially between meals and at night.
When a healthy person eats, insulin is released in two phases. First comes the brief first phase, followed by the slower second phase lasting roughly 1–2 hours. The brief first phase is controlled by hormones released by the intestines in connection with a meal.
If the amount of released insulin is insufficient or if the effect of insulin in the tissues is reduced, the body is unable to process the nutrients in the food normally and the liver makes too much sugar into the blood circulation. This results in blood sugar level becoming too high. Diabetes is also closely linked to a fat and protein metabolism disorder.