Continuous Glucose Monitoring Improves Diabetes Control

A study published in the December issue of the journal Diabetes Care showed that using a continuous glucose monitor helped people with poorly controlled Type 1 diabetes lower their blood glucose levels.


A continuous glucose monitor is a device that consists of a sensor worn under the skin that transmits information about the body’s glucose levels to a receiver. The receiver, which is generally about the size of a pager, displays frequently updated glucose levels and stores information about changes in glucose levels over time. The device can also be programmed to set off alarms when glucose levels become too low or too high.

The study, called the GuardControl Trial, lasted three months and followed 156 adults and children with Type 1 diabetes in seven countries. All of the study participants used either an insulin pump or multiple daily injections to control their blood glucose levels, and all had HbA1c levels (a measure of blood glucose control over two to three months) of 8.1% or higher at the start of the trial.

The participants were divided into three groups: One group used a continuous glucose monitor continuously for three months, one group used it for three days every two weeks, and one group (the control group) did not use it at all. The people who were using continuous glucose monitors were instructed to confirm glucose levels with a fingerstick if the high or low glucose alarms went off and to take corrective action accordingly. People who were not using continuous glucose monitors were instructed to continue monitoring their blood glucose levels by fingerstick as usual.

By the end of the study, 50% of the people who wore a continuous glucose monitor continuously experienced at least a 1% drop in their HbA1c levels, compared to 37% of the people who used a continuous glucose monitor for three days every two weeks and 15% of people who did not use one at all. A greater proportion of the continuous glucose monitoring group also experienced at least a 2% drop in HbA1c levels—26%, compared to 9% of the three-day group and 4% of the control group. What’s more, significant reductions in HbA1c were seen in the continuous monitoring group as early as one month into the trial. A 1% drop in HbA1c level has been associated with a 35% reduction in diabetes complications as well as a significant reduction in health-care costs.

Further studies like this one should help define treatment guidelines for the use of continuous glucose monitors and pave the way for insurance coverage of the devices in the United States.

This study used the Guardian RT Continuous Glucose Monitoring System, which is manufactured by Medtronic MiniMed. Other continuous glucose monitors currently on the market are the STS Continuous Glucose Monitoring System from DexCom and the REAL-Time Continuous Glucose Monitoring system, also from Medtronic MiniMed, in which the receiver is combined with an insulin pump. Another continuous glucose monitor called the FreeStyle Navigator from Abbott Diabetes Care is currently awaiting approval from the U.S. Food and Drug Administration.

For a firsthand account of continuous glucose monitoring, check out “New Monitoring Technology Brings Movies Instead of Snapshots” by Jan Chait.

Learn more about the health and medical experts who who provide you with the cutting-edge resources, tools, news, and more on Diabetes Self-Management.
About Our Experts >>

  • DotConnector

    Yesterday was my first day participating in a trail for the Freestyle Navigator Continuous Glucose Monitor. I have had type one diabetes since I was 14 and have dreamed of having a device that would “tell” me my blood sugar and now I have it.

    I have been on an insulin pump for at least 12 years, went through a very successful pregnancy with it, but labored over the 10-12 finger pricks to stay in control.

    I decided late last night that I should document my experience in this trial as a women living with diabetes, as a mother of a diabetic child and as the wife of a type two husband. So, I started a blog that can be found at

    I can’t tell you how much that last 12 hours wearing this device has changed my perspective about the future of living with diabetes.

    I have hope–real hope for living a long healthy life. long.


  • dbuitt

    Thanks for the article. It is good to kinow that checking your levels can result in good control.

    Very good article.


  • Robin

    I am 47 years old. A friend gave me her EasyPro glucose testing system. Where can I go on the web to find out what these numbers mean after I test my blood? I have been healthy my whole life so this is all new to me, but she feels my sugar levels are out of whack because I’ve been experiencing severe headaches, tiredness, mood swings, etc for over a year. Thank you for your direction as I know not what “normal” blood levels are and what should be a warning sign.

  • Tara Dairman, Web Editor

    Hi Robin,
    Only a medical professional can diagnose diabetes based on the results of blood tests run in a laboratory. You should discuss your symptoms with your doctor or other health-care professional, who may then recommend the test for diabetes.

    You may also want to look at our article Blood Glucose Monitoring: What Do the Numbers Tell You? found in the Magazine Archives section of this Web site. According to the article: Target goals for blood glucose set by the American Diabetes Association (ADA) are 90–130 mg/dl before a meal and less than 180 mg/dl two hours after the start of a meal. The American Association of Clinical Endocrinologists (AACE) has defined stricter blood glucose target goals of less than 110 mg/dl before a meal and less than 140 mg/dl two hours after the start of a meal. Ask your health-care provider whether you should use the ADA or the AACE targets as your goal.

  • Wood Badge Owl

    I have been on the Mini Med Contionous moonitor for 5 months. I am covered by insurance for it. My A1c has dropped 2.1%. Lots of data and I have a notebook from day 1. It has helped greatly. Now on Symlin 2 weeks. I can see what the drug is doing. How great is that. Learned more in the last 5 months than I did the previous 16 years.

  • joanne

    I just learned about the monitor do you know if it is covered by insurance, looks to be a very good thing. I have been on the pump for 10 years.