What is a Continuous Glucose Monitor (CGM)?

Every day, healthcare professionals across disciplines encounter people living with diabetes, whether during routine check-ups, hospital rounds, consultations at the pharmacy counter, or follow-ups in specialty clinics. Increasingly, these patients are using a technology called Continuous Glucose Monitoring (CGM) to manage their condition. But what exactly is a CGM? How does it differ from traditional glucose testing with a glucometer? And why should every healthcare provider, not just diabetes specialists, understand the basics?

Let’s break it down.

What is a CGM?

A Continuous Glucose Monitor or CGM is a wearable device that tracks a person’s glucose (sugar) levels throughout the day and night. Unlike blood glucose meters that provide a single reading at a single moment in time, CGMs offer a real-time stream of glucose data, capturing changes and trends across the day.

Most CGMs consist of:

• A small sensor inserted under the skin (typically on the abdomen, buttocks, or back of the upper arm)
• A transmitter that sends glucose readings wirelessly
• A receiver or smartphone app that displays the data

Depending on the device, readings may be updated every 1 to 5 minutes, with some systems capable of sending alerts for high or low blood glucose levels.

Why is CGM Important?

Understanding glucose trends and not just snapshots can influence the trajectory of diabetes management. CGMs reveal how glucose levels respond to meals, activity, sleep, stress, medications, and more, giving both individuals with diabetes patients and HCPs a fuller picture than was ever possible with fingerstick testing alone.

The benefits of CGM are multiple, a few include:

• Better informed insulin dosing and medication adjustments
• Ability to alert for impending hypoglycemia and hyperglycemia
• Arrows allow users to proactively act rather than react
• Improved A1C levels
• Increased time spent in a safe glucose range (TIR) – do we want to say increased time in range?
• Greater patient confidence and self-management

CGM can be a powerful tool to guide lifestyle changes or detect patterns that warrant medication review even for individuals not taking insulin.  And for those with hypoglycemia unawareness, CGM provides them with a device that improves their safety.   

CGM vs. Fingersticks

Let’s clarify an important point: CGMs don’t always replace fingersticks, but they can dramatically reduce the need for them. Many newer CGMs are factory-calibrated and do not require fingerstick calibration. However, patients may still use fingersticks occasionally to confirm accuracy or during certain clinical situations.

Who Can Benefit from a CGM?

The short answer is everyone with diabetes.

CGM was once reserved for people with Type 1 diabetes, but guidelines and technology have expanded access. Today, CGM is increasingly used by:

• People with Type 2 diabetes on multiple daily insulin injections or basal insulin
• Pregnant individuals with diabetes
• Individuals with frequent or unrecognized hypoglycemia
• Anyone with difficulty managing glucose variability

CGM can also be prescribed as a short-term tool in primary care, inpatient, or transitional care settings to assess glycemic control more thoroughly (see article on professional wear.

What CGMs Are Currently Available?

There are several CGM systems currently available in the U.S., each with unique features, costs, and prescribing channels (e.g., pharmacy or durable medical equipment [DME]).

Below are the most widely used. For a current review and comparison of all CGMs, visit our Find & Compare CGMs page.

Why Should You Be Familiar with CGM?

Whether you’re a primary care provider, pharmacist, hospitalist, nurse, dietitian, or mental health professional, understanding CGM gives you:

• A clearer window into your patients’ daily lives and ability to help them understand lifestyle choices around stress, physical activity, and food choices
• Tools to support medication and lifestyle decisions
• Insight into conversations about alarms, data, and technology use
• A way to collaborate better with diabetes educators, endocrinologists, and patients themselves
  

Key Takeaway

CGMs are transforming the way diabetes is managed. They are no longer niche tools for specialists; they’re becoming standard of care for a growing segment of people with diabetes. As the technology becomes more accessible, healthcare professionals in all settings will increasingly encounter patients using it.

Understanding the basics, what a CGM is, what it does, and how it helps, will empower you to better support your patients, ask smarter questions, and confidently incorporate CGM into care conversations.

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