Insulin is primarily secreted by specialized cells called beta cells, which are located in the islets of Langerhans within the pancreas. These beta cells are highly sensitive to glucose levels in the blood. When blood sugar levels rise, such as after a meal, beta cells release insulin into the bloodstream. Insulin then acts on various cells throughout the body, particularly muscle, fat, and liver cells, to promote the uptake and utilization of glucose, thereby lowering blood sugar levels. This process is crucial for maintaining normal blood sugar levels and providing cells with the energy they need to function properly. In individuals with diabetes mellitus, either the beta cells fail to produce enough insulin or the body’s cells become resistant to the effects of insulin, leading to impaired glucose regulation and elevated blood sugar levels.