Medical Encyclopedia
Summary of the types of CGMS available in the U.S.
Real time systems display results for the user to see and sound alarms when blood sugars are too high or too low.
There are three real-time systems:
-- Two non-integrated, "real time" CGMS available: The Guardian RT and the DexCom STS CGMS; and
-- One integrated real-time system (MiniMed Paradigm REAL-Time System).
There is also one more CGMS, the MiniMed Gold CGMS, which is not a real-time system and is intended for diagnostic purposes as requested by a doctor.
Will my insurance cover the cost of a CGMS?
Depending upon your individual insurance policy most plans will cover the cost if it is being used for a trending test by your doctor. That is, you are hooked up to a CGMS for 3 days to determine trends as part of your treatment plan but do not keep the device.
You doctor can prescribe CGMS trending as often has s/he deems it to be medically important.
CGMS testing for diagnostic purposes is currently reimbursed by Medicare.
Continuous Glucose Monitoring System (CGMS)
Definition of a Continuous Glucose Monitoring System (CGMS) - medical device that measures and logs blood sugar readings frequently during the day and night. It then averages the blood sugar readings.
About the MiniMed System Gold CGMS
The MiniMed System Gold CGMS is not a real-time system and is intended for diagnostic purposes as request by a doctor.
This system is an FDA-approved medical device (co-developed by Medtronic MiniMed and Becton, Dickinson and Company; approved July 2003) that measures and records blood sugar (glucose) levels throughout the day and night.
Picture of MiniMed's System Gold CGMS
How does it work?
Using a cannula, a small "sensor" is inserted under the skin. The sensor must be placed in the abdomen where it then senses blood sugar (glucose) levels every 10 seconds. The readings are sent via a wireless pager to the monitor where the data is recorded. The monitor then averages blood sugar readings every 5 minutes for up to 72 hours before the sensor needs to be replaced.
Three days after beginning the CGMS you must return to your doctor who will upload the readings to a computer and print the anaylsis.
The sensor does not administer insulin and a separate cannula must be worn to infuse insulin from an insulin pump or you will need to continue taking shots.
Misconceptions about MiniMed's System Gold CGMS
The MiniMed System Gold CGMS is not intended for day-to-day monitoring or long-term self-care. Some key points about the Gold CGMS are:
- It does not replace the need for finger-prick blood sugar tests.
- It is not intended to be used for long-term or daily diabetes care management.
- It does not administer insulin.
- It is not kept by the patient and is returned to the doctor's office after three days.
- It is not a "real-time" system. That is, the patient cannot see what readings are being taken until they are uploaded at the doctor's office to a computer and printed out.
What MiniMed System Gold CGMS can do for you
What the System Gold can do is pick up on trends that might otherwise go undetected. For example, the System Gold will pick up low blood sugar readings during the nighttime when the patient is sleeping. It can also evaluate how a person's blood sugar reacts to exercise, food, illness, etc. Understanding these trends can help your doctor make adjustments in your diabetes care plan to keep you blood sugars under better control while reducing the risk of hypoglycemia (low blood sugar)
Picture of Guardian RT System
Things to consider before purchasing the Guardian RT
With CGMS technology you have to calibrate the system with each sensor change and in some cases daily. It will not do away with finger sticks. The sensors on both the Gold and Guardian RT systems are only good for up to 72 hours. Both devices don’t begin working for about 2.5 hours after set up and must be calibrated (with a finger stick blood sugar check) at 2 hours after insertion, again at 6 hours after insertion and then every 12 hours afterwards.
The FDA warning label on CGMS specifically states not to act (treat lows or take insulin) based on sensor readings but to do a finger stick before acting.
CGMS are valuable tools for learning trends, but they do not replace finger sticks and require you to wear to a separate cannula.
The cost of transmitters, sensors and other CGMS-related items can average as much as $400 per month (in addition to your test strips and insulin pump supplies).
Continuous glucose monitoring is not the same thing as a closed loop system.
A closed loop system, which is not yet available, would deliver insulin automatically based on readings taken by CGMS sensors. This would mimic the normal function of the pancreas by constantly making insulin adjustments based on current blood sugar readings and history of insulin already delivered.