Diabetics respond inappropriately to carbohydrate metabolism, and glucose can't enter the cells normally. If body cells become resistant to insulin's effect or if there isn't enough insulin, sugar stays in the blood and accumulates, causing high blood sugar. At the same time, cells starve because there's no insulin to help move sugar into the cells. Diabetes is diagnosed by measuring blood sugar levels. This can begin with a urine test sampled for glucose because excess sugar in the blood spills over into the urine.
Further testing involves taking blood samples after an overnight fast.
Diabetes can result in many complications, including nerve damage, foot and leg ulcers, and eye problems that can lead to blindness. Diabetics also are at greater risk for heart disease, stroke, narrowing of the arteries, and kidney failure. But evidence shows that the better the patient controls his or her blood sugar levels, the greater the chances that the disease's serious complications can be reduced. The first insulin for diabetes was derived from the pancreas of cows and pigs. Today, chemically synthesized human insulin is the most often used.