From the Guidelines
I can interpret a Continuous Glucose Monitoring (CGM) report, though I recommend having a healthcare provider review your specific data for personalized guidance. When interpreting a CGM report, I look at several key metrics including time in range (ideally 70-180 mg/dL for most adults with diabetes for at least 70% of readings), glucose management indicator (GMI, similar to estimated A1C), glucose variability (coefficient of variation ideally below 36%), and patterns of hypoglycemia (below 70 mg/dL) and hyperglycemia (above 180 mg/dL) 1. The ambulatory glucose profile (AGP) is particularly useful, showing median glucose levels and interquartile ranges throughout a typical day. I would analyze overnight patterns, post-meal spikes, and recurring trends at specific times. Understanding these patterns helps identify when medication adjustments, dietary changes, or activity modifications might be beneficial. CGM interpretation requires considering contextual factors like meals, exercise, medication timing, stress, and illness that influence glucose levels, as suggested by the Chinese clinical guidelines for continuous glucose monitoring 1.
Some key points to consider when interpreting a CGM report include:
- Time in range: ideally 70-180 mg/dL for most adults with diabetes for at least 70% of readings
- Glucose management indicator (GMI): similar to estimated A1C
- Glucose variability: coefficient of variation ideally below 36%
- Patterns of hypoglycemia and hyperglycemia: below 70 mg/dL and above 180 mg/dL, respectively
- Ambulatory glucose profile (AGP): shows median glucose levels and interquartile ranges throughout a typical day
- Contextual factors: meals, exercise, medication timing, stress, and illness that influence glucose levels
The data becomes most valuable when correlated with these daily activities to develop targeted interventions for improved glucose management, as recommended by the guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus 1. The most recent and highest quality study, published in 2024, suggests that CGM is essential for creating an ambulatory glucose profile and providing data on time in range, percentage of time spent above and below range, and glycemic variability 1.
From the Research
Interpreting a Continuous Glucose Monitoring (CGM) Report
To interpret a CGM report, it is essential to understand the various components and how they relate to glycemic control. The following points highlight key aspects of CGM interpretation:
- The Ambulatory Glucose Profile (AGP) has been recommended as a standard method for reporting CGM data 2.
- A systematic approach to reviewing CGM data is crucial, especially for internists and family physicians who may have limited time to address complex topics in a typical office visit 3.
- Retrospective CGM data can help clinicians visualize glycemic patterns, and single-page summary views like the AGP Report make rapid interpretation feasible and intuitive 4.
- CGM data can be used to guide therapeutic modifications, optimize glycemic management, and reduce risks of hypoglycemia and hyperglycemia 5.
Key Components of CGM Interpretation
When interpreting a CGM report, consider the following components:
- Glycemic patterns and trends
- Time spent in target glucose range
- Frequency and severity of hypo- and hyperglycemia
- Glycemic variability (GV)
- Insulin dosing and adjustment
- Patient behavior and adherence to treatment plans
Challenges and Barriers to CGM Interpretation
Despite the benefits of CGM, there are challenges and barriers to its adoption, including: