Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar (glucose) levels, and it is primarily used to manage diabetes — particularly Type 1 diabetes and, in some cases, Type 2 diabetes. In people with diabetes, the body either does not produce enough insulin or cannot use it effectively, leading to high blood sugar levels that can cause serious complications over time, including nerve damage, kidney disease, vision loss, and heart problems. Administering insulin via injections or pumps helps replace or supplement the body's own supply, allowing glucose to enter cells and be used for energy. It must be carefully balanced with food intake, exercise, and other medications to avoid both high (hyperglycemia) and low (hypoglycemia) blood sugar. Without proper insulin management, diabetes can become life-threatening. Understanding insulin’s role is key to effective long-term diabetes care and preventing related health complications.