Blood glucose (BG) is a type of sugar that circulates in the bloodstream and is used by cells to fuel their functions. The pancreas produces insulin, a hormone that regulates this delicate balance. It is produced by the liver and stored in muscle and fat cells as glycogen or as BG. The two major BG sources are the breakdown of fats stored in the blood and food intake. Carbohydrates in the diet, including vegetables and fruits, are broken down into BG by the liver. This is called endogenous glucose production or "EGP". The second source is when carbohydrates are not consumed or the body can't process them, the liver converts protein into BG. This is known as gluconeogenesis (GNG)

BG monitoring is a basic practice for diabetes patients. It tells the patient their normal BG range and their level of control over the disease. There are several different types of technologies used to monitor BG levels. BG meters are the most widely available and accurate. They use a small plastic stick dipped in a test strip to measure BG levels. These meters can measure the BG level in the blood drops. They take just a few minutes to get a reading and come in different sizes. They are largely used to test BG levels before and after you eat to determine insulin dosage. They can be used in the clinic or at home. Nowadays, they can test blood sugar levels at different body parts such as the ear lobe, palm, or forearm.

The strip is placed in a lancet pen and a minimal drop of blood is taken through the skin and into the meter. A BG meter can detect illness before the symptoms of feeling unwell. This is extremely helpful for diabetics, particularly in the case of ketoacidosis or hypoglycemia. Diabetic individuals are advised to use a BG meter to keep track of their sugar levels regularly. This enables them to notice the change in their BG level. In case of high BG values, they can take corrective action. Test strips are disposed of after use and require regular replacement. This is because the test strip is designed to be used just once.

Non-invasive BG monitors are used for people with diabetes who need to keep track of their sugar levels regularly. This test is less invasive as a small needle is not used. The body part that requires testing is inserted into a device that measures BG levels in the body. These monitors measure your BG level by placing a small sensor into bodily fluid, such as blood or urine. There are two types of non-invasive blood sugar monitors. Indirect tests are used for people who need to test BG levels only occasionally, are taking insulin, or have a CGM. Sensors can be placed in the abdomen, thigh, or arm. This test is used to monitor blood sugar levels before and after eating.