Glucometer is the device that measures the glucose (sugar) level in the blood. A substantial part of the food we eat gets converted into sugar in the process of digestion and gets mixed in the blood. A very intricate balance of the sugar level in blood is maintained by the two hormones produced by human pancreasPancreas. Breakdown of control mechanism results either in (diabetes) hyperglycemiaHyperglycemia (excess of sugar in blood) or hypoglycemiaHypoglycemia (lower sugar level), both of which are dangerous. The tight sugar control mechanism in the body, symptoms of the two types of sugar abnormalities, mechanism and method of measuring glucose blood level using different measuring instruments, etc., are discussed in this chapter.