Symptoms may seem benign - increased hunger, excessive thirst, frequent urination, weight loss, fatigue - but undiagnosed or uncontrolled disease can take a toll on the body's nerves, eventually damaging the eyes, kidneys and lower limbs, and can raise the risk of a heart attack or stroke.
The two main types of diabetes are Type 1, accounting for 5% to 10% of adult cases, and Type 2, accounting for 90% to 95%. An estimated 1% to 5% of additional cases are caused by surgery, medications, infections and disease.
Type 1 can occur at any age, but is usually diagnosed in childhood or young adulthood. In this form of the disease, the body's immune system attacks beta cells in the pancreas that make the glucose-regulating hormone insulin.
Type 2 occurs as the body loses the ability to use insulin properly and, gradually, the ability to produce it
The disease is insidious and deadly. Though listed as only the seventh-leading cause of death in 2006, it's believed to be dramatically under-reported as a cause - contributing to many more. It's also expensive. Medical costs for people with diabetes are 2.3 times higher than for those without diabetes, government data show.