Final answer:
Excess glucose appears in the urine as a result of type 1 or type 2 diabetes due to a lack of insulin action or insulin resistance, respectively. The resulting high blood glucose levels exceed the kidneys' capacity for reabsorption, leading to glucosuria and the production of ketones from fat metabolism.
Step-by-step explanation:
Excess glucose can be found in the urine as a result of type 1 diabetes or as a result of type 2 diabetes. In both cases, the problem lies in the use of glucose by the body's cells. For people with type 1 diabetes, the pancreas does not produce sufficient insulin, a hormone that helps cells take up glucose from the bloodstream. In type 2 diabetes, cells develop a resistance to insulin, even though it may be present.
Without the action of insulin, glucose cannot enter the cells and remains in the bloodstream. This high level of glucose in the blood can lead to a condition known as glucosuria, where the kidneys' ability to reabsorb glucose is overwhelmed, leading to the excretion of glucose in the urine.
Moreover, when the body is unable to utilize glucose for energy due to a lack of insulin or insulin resistance, it begins to break down fat, resulting in the production of ketones, which are released into the urine. This situation indicates that the body is using fat as its primary energy source instead of glucose.