MODEL RELEASED. Blood glucose test. Man about to put blood from his pricked finger onto a blood glucose test strip. This sort of test can help to diagnose diabetes, a metabolic disorder in which unused sugars accumulate in the blood and urine. It is caused because the body either fails to produce the hormone insulin (type I diabetes) or fails to respond to it properly (type II diabetes). In the healthy body, the release of insulin causes glucose in the blood to be converted to starch-like glycogen for storage. Diabetics must control their blood glucose levels through diet, medication and, in some cases, insulin injections.