Diabetes is a disease where blood glucose levels are too high due to either not enough insulin production or cells not properly responding to insulin. There are two main types: type 1 is usually diagnosed in childhood and type 2 in adulthood. Symptoms include frequent urination, thirst, hunger and fatigue. Complications affect the eyes, heart, kidneys, nerves and risk of infection if blood sugar is not controlled through lifestyle changes like diet, exercise and medication if needed.