Diabetes is a disease where the pancreas no longer produces sufficient amounts of insulin. Insulin is required to make the sugar in the bloodstream (from food) move into the cells of the body, where it is used for energy. If there is no insulin being produced, the sugar stays in the bloodstream and reaches very high levels. High levels of sugar or glucose in the blood cause an overflow of the glucose into the urine, which makes animals with diabetes very prone to urinary tract infections. It also causes the body to break down fat for energy (because glucose is unavailable to the body cells for energy). Breakdown of fat for energy results in ketone bodies, which can make the animal feel sick.