Blog - Diabetes Management
How to Interpret Your Dexcom rtCGM Data
Interpreting rtCGM data to manage diabetes
For people living with diabetes, monitoring blood sugar is important for staying healthy. Learn how sugar levels and glucose is measured, and how real-time continuous glucose monitoring (rtCGM) can help you make in-the-moment decisions to better manage your diabetes.
What is blood sugar monitoring?
Blood sugar monitoring means checking glucose in the blood by using a finger prick blood sugar test kit (or glucometer). People with diabetes must keep a close eye on their glucose levels so they can take action to keep it from getting too high or too low. Your doctor or diabetes healthcare specialist will advise you on how often to check your blood sugar levels, what you target range is and what to do if it’s too high or low.
How are blood sugar and glucose levels measured?
There are different ways to measure blood sugar and blood glucose levels:
1. Blood glucose meter
A blood glucose meter (BGM) measures the amount of sugar in a small sample of blood, usually from your fingertip, that you place on a disposable test strip. The main disadvantage of BGM is that it can only provide a snapshot of your blood sugar level at a moment in time. It can also be inconvenient, requiring you to interrupt your day to prick your finger. Since it only tells you your current level when you test, it can’t inform you of any highs and lows that may occur in between.
2. HbA1C test
As well as regularly testing your own blood sugars, at least once a year, your healthcare team will ask you to come in for an HbA1c blood test. This checks your average blood sugar levels over the last three months and helps your diabetes team and you to spot trends over time.1 It is typically recommended as part of a diabetes management plan that includes regular blood sugar monitoring with a BGM. The at-home monitoring can reveal daily fluctuations and patterns that cannot be identified with the HbA1C test.
3. Flash/intermittent scanning glucose monitoring
A flash glucose monitor (FGM) uses a sensor worn on your body that allows you to test your glucose without having to prick your finger*. Rather than measuring the blood sugar level, this device measures the amount of sugar in the interstitial fluid surrounding your cells. With a flash glucose monitor, you must wave or scan your smart device or handheld receiver over your sensor to get readings, meaning that you’d have to wake up in the middle of the night to do this. On average, users FGM only scan 11.5 times per day2, which may not give you a complete picture of your glucose levels.
4. Real-time continuous glucose monitoring
Continuous glucose monitoring uses a small wearable sensor to measure glucose levels and send those readings automatically to a smart device or handheld CGM receiver. Like flash monitors, they measure the amount of sugar in the interstitial fluid surrounding your cells. With real-time CGM, you don't have to scan your sensor or finger prick* to get readings.
How does Dexcom real-time CGM work?
Dexcom CGM Systems track your glucose levels continuously by taking automatic readings every 5 minutes (up to 244 readings within 24 hours), without finger pricks† or scanning. It translates the readings into easy-to-read data sent to a reciever or compatible smart device‡ in real time. Next to the current reading, they show the direction your glucose is heading—up, down, or steady—so you can make better decisions about food, activity and insulin in the moment. You can also set a range of alerts, such as high and low levels, to receive alerts when you’re above or below your chosen thresholds.
Real-time Dexcom CGM provides accurate3 readings day and night, enabling you to see patterns and access insights that can help improve your diabetes management. It also translates your readings into dynamic data so you're able to better manage your diabetes treatment.4,5,6
† Finger pricks required for diabetes treatment decisions if symptoms or expectations do not match readings
How to get glucose readings with Dexcom CGM apps
Once you have your Dexcom CGM System, you can download the app on your iOS or Android smart device‡ and follow the in-app instructions or User Guide to get started. Here are some features of the Dexcom CGM app and receiver that help you to see and manage your glucose levels:
Number in the circle: Current sensor reading which tells you where your glucose is now and updates every 5 minutes. Depending on the range and alert settings, the colour of the circle may change
Trend arrow: Shows where your glucose is heading and how fast it’s moving, allowing you to take action before your levels go too low or too high
White dot: Your current sensor reading (colour of the circle may change due to range and alerts)
Black dots: Previous sensor readings
Grey section within the graph: Shows your target range, or where you want your glucose to be. If your trend dots are above or below the grey area, it means you were outside your target range at that time. Depending on the device, this is area is fixed to 3.9 and 10.0 mmol/L but can be adjusted
Red line: Your Low Alert level
Yellow line: Your High Alert level
Watch this video to learn more about how to use a Dexcom CGM app to see and manage your glucose levels.
Using your rtCGM to make diabetes management decisions
Dexcom CGM gives you the power to make meaningful diabetes management decisions in the moment thanks to real-time glucose data.
The most important thing to keep an eye on is your current sensor reading, particularly after eating and exercise. Is it in your target range? If your glucose level is out of range, which steps of your plan should you follow? If you’re experiencing hypoglycaemia (low blood sugar levels) make sure you act right away to increase your glucose levels.
Second, look at the trend arrow. The trend arrow is helpful for understanding where your glucose is headed and how you can respond. For example, if your glucose value is 5.0 mmol/L and the trend arrow shows that your levels are rapidly falling, you may need to take action, like having a snack, to prevent hypoglycaemia. If your glucose value is 5.0 mmol/L and it shows your levels are increasing, you might need to increase your activity, such as taking a walk or using insulin, to bring it back down.
Third, leverage the alert features of your rtCGM. Consult with your HCP on the right thresholds for your low and high settings and employ predictive alerts, like the Dexcom Urgent Low soon§,7,8, to get ahead of serious events.
Monitor your rtCGM over time with Dexcom Clarity
Dexcom Clarity is an important part of Dexcom CGM Systems||, providing a holistic view of your diabetes management by highlighting glucose trends and statistics in easy-to-read reports. It can help you identify glucose patterns and, with your healthcare professional (HCP), find ways to improve your management.¶ Download Dexcom Clarity on your iOS or Android smartphone‡ or log in on desktop with your existing Dexcom CGM username and password to take full advantage of your CGM data and insights.
Get Dexcom rtCGM data in the palm of your hand
If you’ve been monitoring your blood sugar with finger pricks or your glucose readings with FGM, switching to Dexcom rtCGM can be a much more convenient and effective option.4,9,10,11 Having real-time glucose readings available at a glance makes it easier to see how food, medication and activity affect your glucose so you can make better diabetes management decisions in the moment. Talk to your doctor to see if rtCGM is right for you.
Compare Dexcom CGM Systems to learn more or find out how you can access CGM through NHS funding.
References:
* Refer to the manufacturer’s user guide for correct usage.
†Finger pricks required for diabetes treatment decisions if symptoms or expectations do not match readings.
‡ Compatible smart device sold separately. For a list of compatible devices, visit dexcom.com/compatibility.
§ The Urgent Low alert is only available with the Dexcom G7 and Dexcom G7.
|| An internet connection is required to send data to Dexcom Clarity.
¶ Patient must first sync their Dexcom CGM data with the Dexcom Clarity app and consent to share their data with their healthcare provider.
1 Diabetes UK. Checking your blood sugar levels. Diabetes.org.uk. https://www.diabetes.org.uk/guide-to-diabetes/managing-your-diabetes/testing. Accessed 22/3/23.
2 Lameijer A, et al. Flash Glucose Monitoring in the Netherlands: Increased monitoring frequency is associated with improvement of glycemic parameters. Diabetes Res Clin Pract. 2021;177:108897.
3 Shah VN, et al. Performance of a factory-calibrated real-time continuous glucose monitoring system utilizing an automated sensor applicator. Diabetes Technol Ther. 2018;20(6):428-433. The study was performed with the G6 but Dexcom ONE uses the same applicator, sensor and algorithm.
4 Lind M, et al. Sustained Intensive Treatment and Long-term Effects on HbA1c Reduction (SILVER Study) by CGM in People With Type 1 Diabetes Treated With MDI. Diabetes Care. 2021;44(1):141-149.
5 Martens T, et al. Effect of continuous glucose monitoring on glycemic control in patients with type 2 diabetes treated with basal insulin: A randomized clinical trial. JAMA. 2021;325(22):2262-2272.
6 Šoupal J, et al. Glycemic Outcomes in Adults with T1D Are Impacted More by Continuous Glucose Monitoring Than by Insulin Delivery Method: 3 Years of Follow‐Up from The COMISAIR Study. Diabetes Care. 2020;43:37-43.
7 Puhr S, et al. Real-World Hypoglycemia Avoidance With a Predictive Low Glucose Alert Does Not Depend on Frequent Screen Views. J Diabetes Sci Technol. 2020;14(1):83-86.
8 Puhr S, et al. Real-world hypoglycemia avoidance with a continuous glucose monitoring system’s predictive low glucose alert. Diabetes Technol Ther. 2019;21(4):155-158.
9 Polonsky WH, et al. The impact of continuous glucose monitoring on markers of quality of life in adults with type 1 diabetes: Further findings from the DIAMOND randomized clinical trial. Diabetes Care. 2017;40(6):736-741
10 Visser MM, et al. Effect of switching from intermittently scanned to real-time continuous glucose monitoring in adults with type 1 diabetes: 24-month results from the randomised ALERTT1 trial. Lancet Diabetes Endocrinol. 2023;11:96–108.
11 Haskova A, et al. Real-time CGM Is Superior to Flash Glucose Monitoring for Glucose Control in Type 1 Diabetes: The CORRIDA Randomized Controlled Trial. Diabetes Care. 2020;43(11):2744-2750
* Refer to the manufacturer’s user guide for correct usage.
†Finger pricks required for diabetes treatment decisions if symptoms or expectations do not match readings.
‡ Compatible smart device sold separately. For a list of compatible devices, visit dexcom.com/compatibility.
§ The Urgent Low alert is only available with the Dexcom G7 and Dexcom G7.
|| An internet connection is required to send data to Dexcom Clarity.
¶ Patient must first sync their Dexcom CGM data with the Dexcom Clarity app and consent to share their data with their healthcare provider.
1 Diabetes UK. Checking your blood sugar levels. Diabetes.org.uk. https://www.diabetes.org.uk/guide-to-diabetes/managing-your-diabetes/testing. Accessed 22/3/23.
2 Lameijer A, et al. Flash Glucose Monitoring in the Netherlands: Increased monitoring frequency is associated with improvement of glycemic parameters. Diabetes Res Clin Pract. 2021;177:108897.
3 Shah VN, et al. Performance of a factory-calibrated real-time continuous glucose monitoring system utilizing an automated sensor applicator. Diabetes Technol Ther. 2018;20(6):428-433. The study was performed with the G6 but Dexcom ONE uses the same applicator, sensor and algorithm.
4 Lind M, et al. Sustained Intensive Treatment and Long-term Effects on HbA1c Reduction (SILVER Study) by CGM in People With Type 1 Diabetes Treated With MDI. Diabetes Care. 2021;44(1):141-149.
5 Martens T, et al. Effect of continuous glucose monitoring on glycemic control in patients with type 2 diabetes treated with basal insulin: A randomized clinical trial. JAMA. 2021;325(22):2262-2272.
6 Šoupal J, et al. Glycemic Outcomes in Adults with T1D Are Impacted More by Continuous Glucose Monitoring Than by Insulin Delivery Method: 3 Years of Follow‐Up from The COMISAIR Study. Diabetes Care. 2020;43:37-43.
7 Puhr S, et al. Real-World Hypoglycemia Avoidance With a Predictive Low Glucose Alert Does Not Depend on Frequent Screen Views. J Diabetes Sci Technol. 2020;14(1):83-86.
8 Puhr S, et al. Real-world hypoglycemia avoidance with a continuous glucose monitoring system’s predictive low glucose alert. Diabetes Technol Ther. 2019;21(4):155-158.
9 Polonsky WH, et al. The impact of continuous glucose monitoring on markers of quality of life in adults with type 1 diabetes: Further findings from the DIAMOND randomized clinical trial. Diabetes Care. 2017;40(6):736-741
10 Visser MM, et al. Effect of switching from intermittently scanned to real-time continuous glucose monitoring in adults with type 1 diabetes: 24-month results from the randomised ALERTT1 trial. Lancet Diabetes Endocrinol. 2023;11:96–108.
11 Haskova A, et al. Real-time CGM Is Superior to Flash Glucose Monitoring for Glucose Control in Type 1 Diabetes: The CORRIDA Randomized Controlled Trial. Diabetes Care. 2020;43(11):2744-2750
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