CGM vs. BGM: Understanding the difference

Both Continuous Glucose Monitoring (CGM) and Blood Glucose Monitoring (BGM) provide valuable insights about your glucose levels, but they function differently and offer unique benefits.

The basics of CGM and BGM

BGM is the traditional method, also known as Self-Monitoring of Blood Glucose (SMBG). With BGMs, you can check your blood sugar levels through finger stick testing. This involves pricking the finger to draw a drop of blood, which is then placed on a test strip and inserted into a blood glucose meter. The frequency of obtaining glucose values is different. Using SMBG, you might test several times a day, typically before meals and bedtime, depending on your type of diabetes and medication. This frequency gives you a value that reflects your blood glucose level at the moment of taking the blood drop for the test.

BGM provides immediate readings at specific times throughout the day, while CGM provides real-time blood glucose monitoring. 1 Your glucose level may change before or after taking the test.

CGM is a modern, real-time blood sugar monitor. By inserting a small sensor under the skin, it can measure glucose levels in the interstitial fluid - the fluid found in the spaces around cells - and send the data to a display device. You get a full picture of glucose levels over the time you are wearing the sensor. This helps you spot trends and patterns so you can better manage blood sugar levels.2

SMBG (left) and CGM glucose level measurement:

Image
 Two charts representing BGM on the left and CGM on the right. BGM is presented with dots, while the CGM chart has curves to help identify patterns.

How to measure glucose with Continuous Glucose Monitoring

CGM systems offer real-time glucose tracking, providing users with immediate insights into their glucose levels. A CGM solution can identify trends in glucose levels and warn you when glucose levels are trending too high or too low so you can take preventive action before a serious event occurs.3 A CGM allows you to see the previous glucose level development, and with the right software support, it can estimate future changes.

With alarms and predictive features enabled, the Accu-Chek SmartGuide CGM solution can predict and notify you of potential glucose excursions.

Which is right for you?

Each measuring approach has advantages. BGM devices are simple and accessible, while CGM solutions offer continuous insights for more in-depth decision-making. Your diabetes care plan may involve using one, or both, based on medical advice or preference.

Both CGM and BGM play crucial roles in diabetes management. The choice depends on lifestyle, personal preferences, and medical needs. You can choose the best method in consultation with a healthcare provider.

If you need real-time glucose tracking and want to reduce the number of finger sticks, CGM may be a good fit. If you prefer a simple yet effective approach and are comfortable with periodic testing, BGM remains a reliable choice. Some may use both CGM and BGM together to enhance accuracy and ensure effective glucose control. Accu-Chek products include both BGM and CGM solutions, providing reliable and user-friendly technology to support effective diabetes management.

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1. Cengiz E, Tamborlane WV. A tale of two compartments: interstitial versus blood glucose monitoring. Diabetes Technol Ther. 2009 Jun;11 Suppl 1(Suppl 1):S11-6. doi: 10.1089/dia.2009.0002. PMID: 19469670; PMCID: PMC2903977.

Maria Ida Maiorino, Simona Signoriello, Antonietta Maio, Paolo Chiodini, Giuseppe Bellastella, Lorenzo Scappaticcio, Miriam Longo, Dario Giugliano, Katherine Esposito; Effects of Continuous Glucose Monitoring on Metrics of Glycemic Control in Diabetes: A Systematic Review With Meta-analysis of Randomized Controlled Trials. Diabetes Care 1 May 2020; 43 (5): 1146–1156. https://doi.org/10.2337/dc19-1459

Glatzer T, Ehrmann D, Gehr B, et al. Clinical Usage and Potential Benefits of a Continuous Glucose Monitoring Predict App. J Diabetes Sci Technol. 2024 Sep;18(5):1009-1013.

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