Most likely, the most common means of diabetes management involves the measurement or monitoring of their blood sugar levels. Two techniques are primarily used to achieve at least two of these goals. These are the Continuous Glucose Monitoring and the Blood Glucose Monitoring. Although they share the same general goal, they do differ in the way in which glucose levels are measured and how accurate they are, and importantly, they also differ concerning how they fit in with one’s daily life.
In this blog, we will discuss the CGM Vs BGM, the benefits of each, their limitations, and why one may be best suited over another for certain types of people managing diabetes.

What is Continuous Glucose Monitoring?

Continuous glucose monitoring systems are tiny, wearable sensors that measure the glucose level in the interstitial fluid surrounding your cells- at least once a minute throughout the day and night. CGM technology consists of a small sensor inserted under the skin, typically on the abdomen or upper arm, which continually monitors glucose levels in the interstitial fluid. This sensor sends glucose data wirelessly to a monitoring device, such as a separate handheld monitor, a smartphone app, or an insulin pump.
Common CGM brands available for distribution include Dexcom, FreeStyle Libre,  and Medtronic Guardian.

How CGM Works:

• Insertion: The sensor is placed beneath the skin by using a special inserter.
• Continuous Data Transmission: The sensor scans glucose levels constantly and transmits data to a receiver or mobile device. The of Dexcom sensors last for 10 days, and Abbott sensors  last for 14 or 15 days.
• Trend Monitoring: Graphical displays will illustrate the trending of glucose levels up and down during the day and night.
• Alerts and Notifications: Most of the available CGM systems offer a facility that features customizable alerts for abnormally high or low glucose levels.

What is Blood Glucose Monitoring (BGM)?

Blood Glucose Monitoring, or Self-Monitoring of Blood Glucose is the old method of obtaining small drops of blood from the pricked finger and placing it on the test strip inserted into the glucose meter. BGM immediately provides a snapshot of blood glucose levels at a given time.
Some popular brands of BGM include Accu-Chek, OneTouch, and Contour Next.

How BGM works:

Finger Prick Lancet used to pierce the skin usually on a fingertip to draw a drop of blood.
Test Strip Blood drop is placed on a test strip inserted in a glucose meter.
An Instant Reading Glucose meter will read the glucose on analyzing the blood sample.

Key Difference Between CGM and BGM

Measurement Frequency:

• CGM: Continuous measurement of glucose levels. Updates every 1 to 5 minutes based on the device.
• BGM: Only measures glucose at a point in time; the patient must apply several finger sticks at intervals during the day.

Data Insights:

• CGM: It offers a clear picture of glucose trends, patterns, and fluctuations over time. This helps users distinguish between the presence of nighttime hypoglycemia and post-meal spikes.
• BGM: It gives one glucose reading at the point of testing time but has no demonstration of the historical trend.

Ease of Use

• CGM: It has the advantage of eliminating frequent finger pricking but demands sensor insertion. It needs to be replaced every 7-14 days based on the brand selected.
• BGM: It does not require a sensor. Instead, it demands a finger prick every time the reading is required. This can be quite inconvenient and uncomfortable in case one has to monitor frequently.

Alerts

• CGM: Most of the CGM devices have alerts that can be customized to alert a person when their glucose is high or low. This is particularly good at preventing dangerous lows, as it will give a warning before they happen.
• BGM: No alerting and no alarm as it just takes a snapshot reading.

Accuracy

• CGM: Measures glucose in interstitial fluid; it can be delayed by a few minutes, especially in situations of a steep increase in glucose. CGMs need to be calibrated with BGM readings depending on the model.
• BGM: Measures glucose directly from the blood, and provides an immediate and accurate reading at the time.

Cost

• CGM Usually more expensive to establish at initiation, including the cost of sensor and receiver, as well as the ongoing cost of replacing sensors every 1-2 weeks.
• BGM is Less expensive to initiate and maintain, but test strips, lancets, and batteries for the meter need to be purchased continually.

Insurance Coverage:

• CGM: Insurance coverage of CGM systems will differ in that some insurance plans may cover the CGMs only to those patients with Type 1 diabetes or with a history of severe hypoglycemia.
• BGM: Blood glucose meters and test strips are covered by the majority of insurance without much restrictions as compared to the CGM system.

Advantages of CGM

• Real-time Glucose Monitoring: CGM provides an uninterrupted flow of glucose data, so they may notice trends and be more in control of diabetes management. This is especially true for those whose glucose levels tend to frequently fluctuate.
• Alerts and Notifications: User-set alerts can even prevent dangerous high and low glucose levels, so a user has time to be proactive to respond before glucose levels reach critical concentrations.
• Insight into Glucose Trends: CGM offers a view of how food, exercise, and insulin affect blood sugar levels at all times. This may allow for better strategies for the management of diabetes.
• Night-time Monitoring: CGM is particularly suited to detect nocturnal hypoglycemia and correct it. Nocturnal hypoglycemia is very dangerous because it strikes at night when asleep leaving the blood sugar far too low.

Advantages of BGM

• Cost-effective: BGM seems to be less expensive than CGM and thus more people with diabetes can purchase BGM. Available and Widely Replaced
• Widely Available: BGM systems are more prevalent and available. Most patients with diabetes are also aware of their use.
• Immediate Blood Sugar Reading: BGM offers an immediate and direct reading of blood glucose, which is very useful for immediate decisions regarding insulin injections or food intake.

Limitations of CGM

• Sensor Insertion: Some find sensor insertion uncomfortable and will endure skin irritation and even infection at insertion sites.
• Cost: The CGM device and its sensor are relatively costly, and insurance may not wholly cover it.
• Require Calibration: Some models must be calibrated using a BGM, which makes it inconvenient in situations like the one above.
• Lag Time: Because the glucose is measured in interstitial fluid rather than blood, the measurement will be delayed by about 10-15 minutes in changing blood glucose levels, especially in rapid changes.

Limitations of BGM

• No Continuous Monitoring: There is no continuity in the data yielded from BGM, and therefore individuals may miss the glucose fluctuations between tests.
• Finger Pricking: The repeated finger pricks are quite painful and inconvenient to people and may reduce the frequency of testing.

Reduced Data: BGM provides only a point-in-time reading, which does not yield the depth of data to understand the trends and patterns of glucose during the day.

Who Should Use CGM?

CGM may be better suited for people who:

• Have fluctuating glucose levels at frequent intervals.
• Experience nighttime hypoglycemia or have an unconscious low blood sugar event.
• Need more data about their glucose trends to gain a better understanding of their diabetes management.
• Want a more hassle- and pain-free experience with no finger pokes.

Who Should Use BGM?

BGM is for patients who:

• Have a lower cost option for the newly diagnosed diabetic.
• Need fewer checks of their glucose per day.
• Have stable glucose patterns in which they don’t need to check them at specific times.
• Need a more cost-effective option.

Conclusion

Both serve to have specific usage in the management of diabetes. CGM can constantly monitor and report changes without a requirement for its restarting; hence, it becomes a source of real-time alerts for changing glucose levels. BGM has been an effective, budget-friendly choice for many patients. Thus, the choice between CGM and BGM will depend on individual needs, budget, and lifestyle. Therefore, one must consult a healthcare provider to determine the best monitoring method for his or her particular situation. Regardless of modality, monitoring blood glucose regularly is essential to good diabetes control and general well-being.