The 6 Best Continuous Glucose Monitors Of 2023 + Signs Of A Blood Sugar Imbalance

Diabetes and blood-sugar-related health concerns affect 1 in 10 Americans, but the best continuous glucose monitors (CGMs) have transformed how easily people can monitor their blood sugar. Of course, that's just the tip of the iceberg. 

Continuous glucose monitors play a critical role in maintaining healthy blood sugar levels1. They provide real-time monitoring of glucose levels, which supports improved management and healthier outcomes.

Blood glucose, commonly known as blood sugar, is a key health indicator. It acts as the primary fuel source for our cells, especially those in the brain. 

Derived mainly from the foods we consume, particularly carbohydrates such as grains, fruits, vegetables, and sugars, glucose is broken down and released into our bloodstream. It is also created by our liver in a process called gluconeogenesis.

The balance of glucose in your blood is controlled by an intricate system involving several hormones, chiefly insulin and glucagon, both produced by the pancreas. After eating, our blood glucose levels increase, signaling the pancreas to produce insulin. This insulin then functions to facilitate glucose absorption by our cells, where it is used for energy or stored for later use. 

When blood glucose levels diminish, the pancreas releases glucagon, which prompts the liberation of stored glucose back into the bloodstream.

Persistent high blood glucose levels, a state known as hyperglycemia, can lead to health complications such as diabetes, heart disease, kidney disease, among others. Conversely, hypoglycemia, or exceedingly low blood glucose levels, can result in a slew of symptoms including weakness, confusion, and in severe cases, loss of consciousness.

A continuous glucose monitor (CGM) is a device that provides real-time measurements of blood glucose levels throughout the day and night. This advanced tool helps people, particularly those with diabetes, actively manage their blood sugar levels.

The primary advantage of a CGM is that it provides a more comprehensive view of blood glucose levels compared to traditional blood glucose testing, which only provides a single point-in-time measurement. A CGM displays glucose direction and rate of change, alerting the user to highs, lows, and rapid changes.

When used mindfully, CGMs offer insights into how diet, physical activity, medication, and illness impact blood sugar levels. This information is extremely beneficial in making decisions about food choices, exercise routines, and medication dosage.

A continuous blood glucose monitor is a valuable tool for a wide range of individuals, particularly for those managing Type 1 or Type 2 diabetes.

People with Type 1 diabetes can greatly benefit from CGMs. These devices provide real-time data and trend information, alerting users to sudden changes in blood glucose levels. This information can be vital in making timely decisions about insulin administration. Some can even pair with insulin pumps for a streamlined diabetic management plan.

CGMs are also beneficial for individuals with Type 2 diabetes, particularly those who require insulin therapy. CGMs help identify patterns and fluctuations in blood sugar levels, which can be instrumental in making necessary lifestyle or medication adjustments.

Women diagnosed with gestational diabetes, a form of diabetes that develops during pregnancy, can also find CGMs useful. It is essential for the health of both mother and baby to manage blood glucose levels effectively—and CGMs offer real-time monitoring to help achieve that balance.

Non-diabetic individuals with conditions that might cause hypoglycemia (low blood sugar), those following specific diets for weight loss like ketogenic or low-carb diets, and those focused on optimizing their health and wellness could also benefit from using a continuous blood glucose monitor.

When considering the purchase of a CGM, several factors should be taken into account. Here are some important criteria to consider:

Accuracy

Again, accuracy can vary between models. To determine accuracy, check the Mean Absolute Relative Difference (MARD) value of the CGM device. A lower MARD signifies a higher level of accuracy.

Price

The cost of CGMs varies based on the brand and specific features. Consider both the upfront costs of the device and the ongoing costs for sensors, transmitters, and any required supplementary devices. Don't forget to inquire about insurance coverage, manufacturer's patient assistance programs, and the availability of generic or third-party components.

Ease of use and comfort

Consider the size, insertion process, and wearability of the CGM. Some models are more comfortable or discreet than others. If the device isn't comfortable or easy to wear, you'll be less likely to use it consistently.

Data management and connectivity

Modern CGMs offer various features, including the ability to share data with your health care provider, compatibility with other devices (like insulin pumps), and smartphone connectivity. Depending on your lifestyle and tech-savviness, these could be significant factors. Some devices can also send real-time glucose readings to your smartphone or smartwatch, while others may require you to scan the sensor to get a reading.

Alerts and alarms

Some CGMs offer customizable alerts for high and low glucose levels, rate of change alerts, and predictive alerts that let you know when you're about to go high or low. If you have trouble recognizing symptoms of hypo- or hyperglycemia, these features might be particularly valuable.

It's worth noting that these figures are general guidelines and may vary depending on individual health factors.

Abnormalities in blood sugar levels can manifest in a variety of ways. Recognizing these signs is fundamental for taking corrective actions, as both high and low blood glucose levels can pose significant health risks.

In extreme cases, very low blood glucose levels can lead to confusion, seizures, or loss of consciousness.

Abnormal blood sugar levels, whether persistently high (hyperglycemia) or low (hypoglycemia), can pose significant health risks if not properly managed.

Chronic hyperglycemia, often associated with diabetes, can lead to long-term complications affecting various organs and systems. 

Continuous glucose monitors are generally accurate, but their precision depends on the specific model of the device, the location of the sensor on the body, and the individual's level of physical activity.

The accuracy of a CGM is often evaluated using a measure known as the Mean Absolute Relative Difference (MARD)2. MARD is the average of the absolute error between the CGM readings and the reference blood glucose measurements. A lower MARD percentage signifies a higher level of accuracy.

Most modern CGMs have a MARD that falls between 9% and 12%, making them quite reliable. However, even the most accurate CGM devices can occasionally produce incorrect readings due to factors such as pressure-induced sensor attenuations (e.g., sleeping on the sensor), changes in temperature, or dehydration.

CGMs measure glucose in the interstitial fluid (fluid between the cells), not directly in the bloodstream. Therefore, there can be a lag of about five to 10 minutes between blood glucose and interstitial glucose readings. This lag can make it seem like the CGM is inaccurate at times when blood glucose levels are changing rapidly, such as after eating or during exercise.

Despite these considerations, CGMs are an impactful tool for many people in managing blood glucose levels. Regular calibration, if the device requires it, and following the manufacturer's instructions for use and sensor placement, can help ensure the most accurate readings.