Diabetes mellitus (DM) is a disease of inadequate blood glucose control. It has many subclassifications, including type 1, type 2, maturity-onset diabetes of the young (MODY), gestational diabetes, neonatal diabetes, and steroid-induced diabetes. Diabetes mellitus leads to macrovascular and microvascular complications, leading to life-threatening conditions. The patient's age plays an important role in the development of diabetes. Diabetes in children is also not uncommon, although its incidence is low in newborns. Calorie restriction to restore body weight to normal is associated with increased insulin response even before normal weight is achieved. Moreover, physical activity is important because it increases the peripheral utilization of glucose. In the case when lifestyle changes are not sufficient to correct the diabetic condition, oral antidiabetic therapy is indicated. In diabetes mellitus, insulin is administered in such a way that it mimics its normal secretion, and it can be administered perorally or subcutaneously - intermittently or by continuous infusion - with a pump.