Blood glucose, commonly known as blood sugar, is a key health indicator. It acts as the primary fuel source for our cells, especially those in the brain. 

Derived mainly from the foods we consume, particularly carbohydrates such as grains, fruits, vegetables, and sugars, glucose is broken down and released into our bloodstream. It is also created by our liver in a process called gluconeogenesis.

The balance of glucose in your blood is controlled by an intricate system involving several hormones, chiefly insulin and glucagon, both produced by the pancreas. After eating, our blood glucose levels increase, signaling the pancreas to produce insulin. This insulin then functions to facilitate glucose absorption by our cells, where it is used for energy or stored for later use. 

When blood glucose levels diminish, the pancreas releases glucagon, which prompts the liberation of stored glucose back into the bloodstream.

Persistent high blood glucose levels, a state known as hyperglycemia, can lead to health complications such as diabetes, heart disease, kidney disease, among others. Conversely, hypoglycemia, or exceedingly low blood glucose levels, can result in a slew of symptoms including weakness, confusion, and in severe cases, loss of consciousness.

Monitoring blood glucose levels is especially important for individuals with diabetes. This is where CGMs are instrumental, as they provide real-time data on glucose levels, aiding individuals in better managing their health.