Diabetes mellitus is caused by a disorder of the pancreas function. As a result, this organ is unable to produce sufficient amounts of the insulin hormone. After every meal, insulin ensures that excess sugar from the blood can enter the body's cells. Sugar is needed there to generate energy. Insulin also causes the metabolism to store excess sugar as glycogen (storage substance in the muscles) and body fat.
In diabetics, insulin deficiency leads to an interruption in the transport of sugar into the body's cells and thus to an increase in blood sugar levels. The excess sugar in the blood is partially excreted via the kidneys. That's why the excretion of sugar in the urine is a sign of diabetes. Since little or no glucose is available for energy production in the body's cells, untreated diabetics also experience changes in protein and fat metabolism.
In type 1 diabetes mellitus, the pancreas cannot produce insulin, so insulin must be administered regularly. In insulin resistance, a precursor to type 2 diabetes mellitus, insulin has a limited effect. If insulin no longer works at all, the blood sugar level is permanently elevated – this is type 2 diabetes mellitus
