Several high-tech devices can monitor glucose levels 24 hours a day rather than at just one point in time, giving you unprecedented information on how well you are managing your diabetes. Most useful to avoid hypoglycemic episodes in those whose diabetes requires insulin, continuous monitoring can benefit all individuals with either type 1 or type 2 diabetes. But is a continuous glucose monitor really right for you? Here's information to help you decide.
Continuous glucose monitors can enable you to spot general trends in how well you are controlling your blood glucose, recognize whether it is on its way up or down, and help determine adjustments in your treatment. Better yet, the new sensors even include alarms that can warn you if your blood glucose is too low or too high. Such continuous glucose monitoring has been compared to having your own security camera rather than just occasional snapshots of your home. Whereas traditional finger-prick blood tests give a snapshot of your blood sugar levels, continuous glucose monitors track fluctuations continuously over several days.
Six continuous glucose monitors are approved by the U.S. Food and Drug Administration (FDA): CGMS System Gold, Guardian REAL-time System, Guardian RT, MiniMed Paradigm REAL-Time System (all from Medtronic), DexCom STS, and The Abbott FreeStyle Navigator.
All of the devices use a tiny, flexible sensor that is inserted via a needle under the skin of your abdomen to measure blood glucose levels in the fluid outside of cells (extracellular fluid). The sensor connects to a transmitter that is attached to the skin by an adhesive patch; the transmitter sends real-time data every one to five minutes to a pager-sized receiver with a visible display that attaches to your belt or the waistline of your pants.
The amount of glucose in the extracellular fluid reflects the level in your bloodstream, although there is a lag time of 20-30 minutes before changes in blood glucose are reflected in the extracellular fluid. The readings can be downloaded later to a computer to produce charts that show the average trends of a person's glucose levels over three days. As with other home glucose tests, all continuous glucose monitors must be calibrated with a finger-prick blood test and checked to make sure they are working properly.
Unfortunately, continuous monitors are costly and health insurance coverage is presently a real problem. The few successes in obtaining coverage have required strong advocacy by the prescribing physician. You will definitely need a doctor's prescription and a strong letter of medical necessity before you can expect coverage. So carefully consider the cost not only of the device, which can run in the thousands, but also of the disposable supplies. The sensors may cost about $35 a day, which is a big expense over the course of a year.
Our recommendation: At the moment, we consider continuous monitoring most useful for people who have had severe swings in their blood glucose despite good self-care patterns and, especially, for those who have been troubled by severe hypoglycemia. We are aware that insurance coverage is still spotty but hope that it will improve.
