What are CGMs? Let’s Look at Continuous Glucose Monitors
Diabetes mellitus, Latin for “sweet urine,” has been documented for over 2,000 years. It was once recognized as a devastating and deadly disease. In the 17th century Dr. Thomas Willis, a physician from London, would diagnosis patients with diabetes by sampling their urine. If the patient’s urine had a “sweet taste,” he would diagnose them with diabetes mellitus or “honeyed” urine. This method of monitoring blood sugars really went unchanged until the early 20th century.
In fact, insulin was only discovered in Ontario, Canada in 1921! Dr. Frederick Banting and his assist Dr. Charles Best were able to keep a diabetic dog alive for 70 days. They injected the dog with a concoction of canine pancreas extract.
Other physicians helped refine extracted insulin. Leonard Thompson was the first person to ever receive “exogenous” insulin (insulin originating from outside an organism). Leonard Thompson was a young boy dying of diabetes. However, within 24 hours after receiving the insulin injection his dangerously high blood sugars dropped to near normal and he came out of his coma; his life was saved. Until this discovery of insulin, children diagnosed with diabetes were expected to live less than a year. The news of this new extract, insulin, spread around the world.
What about testing?
Since insulin’s discovery, medical breakthroughs have continued to prolong and ease the lives of people who are diagnosed with diabetes. But what about testing? Testing blood and urine to get accurate data for dosing insulin was in its infancy at the time of insulin discovery. Only recently, in the 1960’s, were urine strips developed. Urine strips help a person with diabetes gain knowledge on how much sugar is in the blood stream. This allows people to dose themselves with insulin with better accuracy.
The first portable glucose meter was created in 1969 by Ames Diagnostics.
Diabetes Health board member Dr. Richard Bernstein, in his book titled Diabetes Type II, Including Type I, describes his first Ames meter: “In October of 1969, I (Dr. Bernstein) came across an advertisement for a new device to help emergency rooms distinguish between unconscious diabetics and unconscious drunks when the laboratories were closed at night…The instrument had a four-inch galvanometer with a jeweled bearing, weighed three pounds, and cost $650.” (1)
Thankfully, new technologies have enabled glucose (sugar) monitors to be made the size of calculators, even smaller; carrying around a 3-pound meter is in the past.
With current inventions, CGM’s or continuous glucose monitors are FDA approved systems that track blood sugar (blood glucose) levels day and night. CGM’s can assist people, who have diabetes, in keeping a “closer eye” on blood sugar levels and making decisions in real live time. CGM’s can also help detect trends and patterns that give the person and their physician a much more complete and accurate picture. This can help in finding better ways to manage diabetes.
What does a CGM do?
The CGM measures the amount of glucose in the fluid inside the body. There are different devices that can collect this information using tiny sensors that can be attached to the skin or implanted. The transmitter on the sensor then sends information to a wireless-pager-like monitor or you can have the information sent to a smart phone. It is also possible to download data to a computer, tablet, or smart phone to watch for trends. The information gathered can help the person with diabetes, their significant other, and their doctor make the best plan to manage diabetes. CGM’s are a tool; you may still need to measure blood sugar with a fingerstick glucometer once in a while.
There are some CGM’s that can be linked to an insulin pump for continuous care. This means you won’t need to manually program the pump, as with the finger prick method.
So why use CGM’s?
Unlike traditional finger stick glucose monitors, CGM’s record your blood sugar levels throughout the entire day and night. It also shows high blood sugars and low blood sugars. CGM systems can help:
- Record dangerously low overnight blood sugar levels, which often go undetected
- Track high levels between meals
- Show early morning spikes in blood sugar
- Evaluate how diet and exercise affect you
- Determine if your treatment plan works on a day-to-day basis
CGM’s are not right for every person with diabetes. And there is a cost to consider; they are more expensive than finger-stick monitors. Insurances may not always cover them, even with a physician’s script. There is also a learning curve, a need to practice, and the time allowance for trouble-shooting issues that all needs to be taken into account.
The Future of CGM’s
At present, all CGM’s require some form of a sensor attached to the skin. Scientists are testing new and better types of CGM systems in clinical trials all the time. There is even one from ASHENSIA that is working on Bluetooth capability that would have no sensor attached to the skin, which would be a major breakthrough.
If you would like more information please reach out to me, Amy Simon, asimon@MilestonePA.org.
1. Al-Samarrie, Nadia. “The History of Diabetes.” Diabetes Health, 1 Jan. 2015, www. diabeteshealth.com/the-history-of-diabetes
2. Hirsch, Irl B. and University of Washington, Seattle, WA. “History of Glucose Monitoring.” Professional.Diabetes.org, professional.diabetes.org/sites/professional.diabetes.org/files/media/db201811.pdf. Accessed Dec. 2022.
