Even with the best calibration possible, there can sometimes be differences in the level of glucose in your blood and the level of glucose in your interstitial fluid because of the way the body uses glucose. A noticeable difference is particularly likely if the glucose level in your blood is changing rapidly, which can occur just after eating or taking insulin or during exercise, but there can be differences at other times, too. It is best not to calibrate your continuous monitoring device when your blood glucose level is likely to be changing rapidly. Some people find the best time to calibrate is just before a meal.
With time and experience, you will learn when the difference between the sensor readings and your blood glucose monitoring readings is normal and when there may be a technical problem that needs addressing, such as a sensor that needs changing. If you’re concerned about the accuracy of your readings, however, speak to your health-care provider, or call your monitor’s manufacturer for help.
It may take some time to get the most from continuous glucose monitoring. Start by learning as much as you can about the technical aspects of your new device, such as how to insert the sensor properly, how to calibrate the device with fingerstick blood glucose readings, how to set the alarms, how to put the alarms on vibrate mode, and how to transfer your monitoring data to a computer. Once you are up to speed on operating the system, you can work on learning to analyze and respond to the information you’re getting from it.
Don’t be surprised if you have an emotional response to seeing all of the glucose changes you experience over the course of a day. For some people, all this new information can be confusing or even frightening. If you’re feeling overwhelmed, try not to tune out, but instead take the challenge to see how you can use this technology to help your diabetes care. Although there is a lot of information, you will quickly learn how to focus on the important trends and worry less about each individual number.
Keep in mind that even though you are using a continuous monitor, there are still times you should use your blood glucose meter. For example, you should still check your blood glucose level with your meter if you have symptoms of low blood glucose (hypoglycemia) and before making any diabetes care changes, including taking a “correction” dose of insulin for high blood glucose. (Also remember to consider how much insulin is already active in your system before you take more.) You should also check your blood glucose level before driving or doing anything that could be dangerous if you had low blood glucose.
Responding to your readings
Continuous glucose monitoring can offer information that can be of use immediately, over the intermediate term, and over the longer term.
Immediate information. Your blood glucose meter gives you point-in-time blood glucose levels, so you know where your blood glucose is, but not necessarily where it’s going. Your continuous monitor, on the other hand, reports glucose levels every few minutes, so you can see not only where it is but also which direction it’s headed. With this added information, you may decide to respond differently to the same number, depending on whether your glucose is rising or falling. Being able to see trends in your glucose levels may enable you to take preventive action—by eating a snack, for example—before your glucose reaches a level considered problematic.
As you use this new technology, you may discover that you don’t always know how to respond to the glucose trends you’re seeing. Should you take more insulin? Less insulin? Delay your meal? Do something different before eating a similar meal in the future?