Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes tends to progress in severity, and is due to either a reduced production of the hormone insulin by the pancreas or unresponsiveness of bodily cells to insulin's effects. Classic symptoms include the three Ps: polydipsia, polyuria, and polyphagia, together with weight loss and blurred vision. If left untreated, the disease can lead to many health complications, including disorders of the cardiovascular system, eye, kidney, and nerves.