Continuous glucose monitors (CGMs) are an increasingly common technology for managing type 2 diabetes. This tool provides insights into glucose levels throughout the day and night, offering a complete picture of how the body responds to various factors. CGM systems help individuals approach their condition with more informed and proactive self-management.
Understanding Continuous Glucose Monitoring
A Continuous Glucose Monitor (CGM) system uses three main components: a small, wearable sensor, a transmitter, and a display device. The sensor is inserted just beneath the skin, often on the belly or arm, and remains in place for several days to weeks. It measures glucose levels in the interstitial fluid, the fluid surrounding cells, rather than directly from the blood.
Interstitial fluid glucose levels closely mirror blood glucose levels, though a slight time lag (5 to 20 minutes) can occur during rapid changes. A transmitter attached to the sensor wirelessly sends readings to a display device. This display can be a dedicated receiver, a compatible smartphone application, or an insulin pump, providing constant updates on glucose trends.
CGM Versus Traditional Finger-Prick Testing
Traditional blood glucose monitoring (BGM) with finger-prick tests provides a single snapshot of glucose levels at a moment in time. This method requires drawing a small blood sample, giving discrete readings that indicate glucose concentration only at the instant the test is performed. While accurate for that specific point, it does not reveal the direction or speed of glucose changes between measurements.
A continuous glucose monitor, in contrast, offers a continuous “movie” of glucose levels by taking readings every few minutes throughout the day and night. This constant data stream allows users to see trends, such as whether glucose levels are rising, falling, or remaining stable. CGM systems provide trend arrows, which indicate the direction and rate of glucose movement, offering a proactive view of changes. They also reveal overnight glucose patterns and post-meal spikes that might otherwise go undetected without frequent finger-pricks.
Acquiring and Paying for a CGM
Obtaining a Continuous Glucose Monitor for type 2 diabetes begins with a consultation with a healthcare provider. A doctor’s prescription is necessary, as CGMs are prescription-only devices. During this visit, the provider assesses whether CGM use is suitable and ensures the individual or caregiver is trained to use the system.
Insurance coverage for CGMs for type 2 diabetes has expanded, but criteria vary among plans. Many commercial health insurance plans now cover CGMs, particularly for those taking multiple daily injections of insulin or using an insulin pump. Medicare expanded its coverage in 2023 to include people with type 2 diabetes who use any type of insulin, and those not on insulin but with a history of problematic low blood sugar events. If insurance denies coverage, individuals can appeal the decision, and some CGM manufacturers offer patient assistance programs or discounts to help manage out-of-pocket costs.
Leveraging CGM Data for Health Management
The data from a Continuous Glucose Monitor offers a tool for informed health management. A key metric is “Time in Range” (TIR), representing the percentage of time glucose levels remain within a target range, typically 70 to 180 mg/dL. This metric complements the A1c test, which provides an average glucose level over three months but does not show daily fluctuations. Aiming for at least 70% Time in Range (approximately 17 hours per day) is a common goal recommended by organizations like the American Diabetes Association.
Real-time feedback from a CGM allows individuals to observe the immediate impact of foods, exercise, stress, and illness on their glucose levels. For example, seeing a glucose spike after a meal can help a person adjust future dietary choices, while observing stable levels during an activity can reinforce positive behaviors. These insights facilitate personalized lifestyle adjustments and enable productive discussions with healthcare providers to optimize treatment plans. The ability to receive alerts for high or low glucose levels also supports proactive management, helping to prevent or address episodes before they become serious.