MODEL RELEASED. Blood glucose test. Close up of a woman using a pen-like lancing device to prick her finger before a blood glucose test. Diabetics have to perform this test regularly. Diabetes is a metabolic disorder in which unused sugars accumulate in the blood and urine. Monitoring of blood glucose levels allows diabetics to control the disease through diet, medication and in some cases insulin injections. The pen is designed to make drawing blood less painful.