Insulin is a hormone secreted by the pancreas that allows s your body to utilize sugar  from carbohydrates in food you eat . It maintains blood sugar level from getting too high or too low.

After eating levels of blood glucose rises, Beta cells are released from pancreas in your blood stream to decrease amount of glucose in blood by helping glucose enter to the cell producing energy.

The islets of langerhans in pancreas contain alpha (α), beta (β) cells.

Alpha cells which release glucagon & beta cells release insulin. Insulin has an important role in lowering blood glucose concentration in hyperglycemic response by increasing rate of glucose into the muscle cells and it  facilitates a glucose utilization and it help in maintaining normal blood glucose concentrations.

Insulin is a hypoglycemic hormone by lowering blood glucose concentration but glucagon is a hyperglycemic hormone. It stimulates gluconeogenesis and stimulates lipolysis to rise blood glucose concentration.

insulin stimulates body gain by promoting protein and fat synthesis. So people who need to lose their weights are always advised with low intake of sugar and carbohydrates to avoid stimulating insulin secretion.