Continuous glucose monitoring (CGM) vs blood glucose monitoring (BGM)

Ready to learn more about how CGM works? Let's dig deeper into the differences between CGM and BGM.

The CGM difference

  • Think of glucose readings as the cars of a train, where the front of the train is blood glucose and the back of the train is sensor glucose.1 Because glucose enters the bloodstream first, blood glucose readings lead sensor glucose readings.1 Eventually, sensor glucose readings catch up to blood glucose readings just like the back of the train following the front of the train.1 BGM provides a glucose value for the specific point in time when a blood drop is read, whereas CGM gives you a more complete picture of where your glucose is going, and where your glucose has been, so you can make more informed treatment decisions.1

  • The insights from CGM can help you figure out what has triggered a spike or a drop in glucose levels, such as exercise or something you ate.

    "Right away I started wanting to modify my behavior to get better results." - Vykki, CGM User

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See the full

CGM shows you where your glucose levels were, where they are in the moment, and where they’re headed. It also helps you see the impact of food, medicine, physical activity on your glucose levels. When you can see trends and patterns, you can make more informed insulin dosing decisions. 

No fingersticks*†

CGM uses a small sensor paired with your smartphone or a reader, instead of fingersticks.*†

Feel in control

CGM is clinically proven to significantly reduce hypoglycemia,ǁ2,3 day and night, while also lowering A1c levels.ǁ4,5 Some CGM systems even have optional alarms that warn when glucose levels are outside of the target range.

How it works

Instead of taking glucose readings from your blood, CGM sensor glucose readings are taken from the interstitial fluid (ISF), a thin layer of fluid that surrounds the cells of the tissues below your skin. Blood glucose readings tend to be about 5 to 10 minutes ahead of interstitial glucose readings.

The more affordable CGM system#**6

Managing your diabetes shouldn't break the bank. See how insurance and Medicare§7 can help cover the cost.
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Ready to get started with a FREE†† trial?

Sign up for the MyFreeStyle program to try one of the FreeStyle Libre systems (CGM) —at no cost.††
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Medicare coverage is available for FreeStyle Libre systems if their respective readers are used to review glucose data on some days every month. Medicare and other third party payor criteria apply.

Abbott provides this information as a courtesy, it is subject to change and interpretation. The customer is ultimately responsible for determining the appropriate codes, coverage, and payment policies for individual patients. Abbott does not guarantee third party coverage or payment for our products or reimburse customers for claims that are denied by third party payors.

* FreeStyle Libre 2 system: Fingersticks are required if your glucose alarms and readings do not match symptoms or when you see Check Blood Glucose symbol during the first 12 hours.

† FreeStyle Libre 14 day system: Fingersticks are required for treatment decisions when you see Check Blood Glucose symbol, when symptoms do not match system readings, when you suspect readings may be inaccurate, or when you experience symptoms that may be due to high or low blood glucose.

‡ The FreeStyle LibreLink app is only compatible with certain mobile devices and operating systems. Please check our compatibility guide for more information about device compatibility before using the app. Use of the FreeStyle LibreLink app requires registration with LibreView.

II Data from this study was collected with the outside US version of Freestyle Libre 14 day system. Freestyle Libre 2 has the same features as Freestyle Libre 14 day system with optional, real-time glucose alarms. Therefore, the study data is applicable to both products.

¶ Notifications will only be received when alarms are turned on and the sensor is within 20 feet of the reading device.

# Based on a comparison of list prices of the FreeStyle Libre 2 system versus competitors’ CGM systems. The actual cost to patients may or may not be lower than other CGM systems, depending on the amount covered by insurance, if any.

** Based on a comparison of list prices of the FreeStyle Libre 14 day system versus competitors’ CGM systems. The actual cost to patients may or may not be lower than other CGM systems, depending on the amount covered by insurance, if any.

§ Patients must meet Medicare eligibility coverage criteria.

†† or ♢ Eligible patients will receive one (1) FreeStyle Libre 2 sensor or (1) FreeStyle Libre 3 sensor for users with a compatible mobile phone operating system at $0 copay. The expiration date of the voucher is 60 days from the issue date. This program is available for patients with Type 1, Type 2, or gestational diabetes. Patients ages 18 and older are eligible to sign up and receive an offer for the (1) FreeStyle Libre 2 sensor or (1) FreeStyle Libre 3 sensor. Patients ages 4-17 are eligible to receive an offer for the (1) FreeStyle Libre 2 sensor or (1) FreeStyle Libre 3 sensor through their parent or guardian. This offer is void where prohibited by law. Abbott may modify or rescind this offer at any time without notice. The discounts are not available to beneficiaries of Kaiser Permanente, Medicare, Medicaid or other federal or state healthcare programs, residents of Massachusetts, or US territories (other than Puerto Rico). The free (1) FreeStyle Libre 2 sensor or (1) FreeStyle Libre 3 sensor is provided as a sample and is limited to one sample per eligible person per product identification number. The FreeStyle Libre 2 sensor or FreeStyle Libre 3 sensor cannot be re-sold, traded nor submitted to any third-party payer for reimbursement and is not provided as any inducement for future purchases. The free sample card is not health insurance.
References: 1. Cengiz, Eda, and William V Tamborlane. “A Tale of Two Compartments: Interstitial Versus Blood Glucose Monitoring.” Diabetes Technology & Therapeutics 11, Suppl 1 (June 2009): S11-6. doi:10.1089/dia.2009.0002. 2. Bolinder, Jan, et al. “Novel Glucose-sensing Technology and Hypoglycaemia in Type 1 Diabetes: a Multicentre, Non-masked, Randomised Controlled Trial.” The Lancet 10057, no. 388 (September 2016): 2254-2263. 3. Haak, Thomas, et al. “Flash Glucose-Sensing Technology as a Replacement for Blood Glucose Monitoring for the Management of Insulin-treated Type 2 Diabetes: a Multicentre, Open-label Randomised Controlled Trial.” Diabetes Therapy 8, no. 1 (February 2017): 55-73. 4. Evans, Mark, et al. “The Impact of Flash Glucose Monitoring on Glycaemic Control as Measured by HbA1c: a Meta-analysis of Clinical Trials and Real-world Observational Studies.” Diabetes Therapy 11, no. 1 (January 2020): 83-95. 5. Kroeger, Jens, Peter Fasching, and Helene Hanaire. “Three European Retrospective Real-World Chart Review Studies to Determine the Effectiveness of Flash Glucose Monitoring on HbA1c in Adults with Type 2 Diabetes.” Diabetes Therapy 11, no. 1 (January 2020): 279-291. 6. Data on file. Abbott Diabetes Care. 7. Local Coverage Determination (LCD) L33822, Glucose Monitors,

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