A diabetic gives himself an intramuscular insulin injection. Diabetes is usually caused by insufficient pancreatic production of insulin, which is the hormone responsible for the absorption of glucose from the blood by the cells. Deficiency results in rising blood glucose levels, causing thirst and excretion of sugar in the urine, weight loss, hunger and fatigue. If insulin replacement therapy is not administered in serious cases, coma and death may occur. Two to four injections each day plus careful control of carbohydrate intake usually prevent marked fluctuations in blood glucose levels. In milder cases diet control is sufficient.