Continuous Glucose Monitoring
How to Read a CGM Report: AGP and Glucose Patterns
Written by Dr. Ajay V. Kaduskar, Diabetologist, Nagpur
MD (Medicine), PGDHSc (Diabetology), FEACD (The Netherlands)
Published · 5 min read
Quick answer
A CGM report usually shows the Ambulatory Glucose Profile (AGP), a graph that combines your readings over 14 days into one typical day. Key numbers are time in range, time above and below range, average glucose, the glucose management indicator (GMI) and variability. Look for patterns: when sugars rise, when they fall, and how steady the line is. Review them with your doctor.
After wearing a continuous glucose monitor for two weeks, you receive a report full of charts and numbers. It can look overwhelming. In truth, only a few parts matter, and learning them helps you see what is happening with your diabetes.
What is the AGP?
The AGP is a standard report format used worldwide. It includes:
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A summary of key metrics
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A bar showing time in each range
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A graph of a typical day, built from 14 days of data
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Daily graphs for each day
What are the key metrics?
Time in range (TIR)
The percentage of time your glucose stays between 70 and 180 mg/dL. The common goal is above 70 percent.
Time above range (TAR)
The percentage of time above 180 mg/dL, with a separate figure for above 250 mg/dL. Lower is better.
Time below range (TBR)
The percentage of time below 70 mg/dL, and below 54 mg/dL. These should be as low as possible, ideally less than 4 percent and less than 1 percent.
Average glucose
The mean of all readings. It is similar to HbA1c but covers only the wearing period.
Glucose management indicator (GMI)
An estimated HbA1c calculated from the CGM average. It may differ from your lab HbA1c.
Glucose variability (CV)
The coefficient of variation shows how much your glucose swings. A value of 36 percent or lower suggests stable sugars.
Sensor use
The report should show that you wore the sensor for at least 70 percent of the 14 days. Otherwise, the data may not represent your usual pattern.
How do you read the AGP graph?
The graph has a central line, the median glucose, and shaded bands around it.
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Median line (50th percentile): Your typical glucose at each time of day.
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Dark band (25th to 75th percentile): Where half of your readings fall.
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Light band (5th to 95th percentile): Where most readings fall. A wide band means large swings.
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Target range lines: Usually at 70 and 180 mg/dL.
A flat, narrow band within the target range is the ideal picture.
What patterns should you look for?
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Post-meal peaks: A rise after breakfast, lunch or dinner. This suggests food portions or timing need review.
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Early morning rise: Sometimes called the dawn phenomenon. It happens due to morning hormones.
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Night-time lows: Dips below 70 mg/dL during sleep need urgent review of medicines.
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Daytime lows before meals: May be a sign of medicine timing problems.
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High overnight plateau: May be due to a heavy dinner or insufficient medicine.
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Wide swings: Suggest inconsistent meals, activity or medicine timing.
How do you use the report?
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Check sensor wear and time in range first.
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Look at time below range. Fix low readings before high ones.
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Look for patterns that repeat across several days.
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Compare with your food, activity, sleep and medicine diary.
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Pick one or two changes to try, such as a smaller dinner or a post-meal walk.
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Review again after the next sensor.
What mistakes should you avoid?
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Reacting to a single reading rather than patterns
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Changing medicine doses without your doctor
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Ignoring low readings that occur at night
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Comparing your numbers with someone else's
When should you see a doctor?
Contact your doctor if you see frequent lows, long periods above 250 mg/dL, sudden changes from your usual pattern or if the numbers confuse you.
A quick recap
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The AGP combines 14 days of CGM data into one typical day.
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Focus on time in range, time below range and variability.
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Look for repeated patterns, not single readings.
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Fix lows first, then address highs.
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Review the report with your doctor and plan small changes.
A CGM report is a map, and your doctor helps you read it. Small, steady changes based on real patterns improve control and safety. To review your report, consult Dr. Ajay V. Kaduskar, a diabetologist at Niramay Clinics in Nagpur.
Sources and further reading
Frequently asked questions
The Ambulatory Glucose Profile is a standard one-page CGM report. It shows time in range, average glucose, variability and a graph of a typical day built from about 14 days of data.
The GMI is an estimated HbA1c from CGM data. A GMI near 7 percent corresponds to an average glucose of around 154 mg/dL. Targets vary by person, so ask your doctor.
It means your glucose varies a lot at that time of day. A narrower band suggests steadier control. Wide bands often signal inconsistent meals, activity or medicine timing.
CGM reflects only the days you wore the sensor, while HbA1c covers about three months. Individual differences in red blood cell life can also cause gaps. Both are useful.
At least 14 days, with the sensor worn for 70 percent or more of that time, gives a reliable picture of your patterns.
It is a natural early-morning rise in glucose caused by hormones such as cortisol and growth hormone. It is common in diabetes. If it is high, your doctor may adjust treatment.
Related reading
- Full guide: continuous glucose monitoring
- What Is Time in Range (TIR) in Diabetes?
- CGM vs Glucometer: Which Is Better for Type 2 Diabetes?
- CGM in Pregnancy: When It Helps and What to Know
- Does Everyone With Type 2 Diabetes Need a CGM?
If you would like advice suited to your own reports and medicines, you can book an appointment or visit Niramay Clinics in Dhantoli, Nagpur.
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Call 0712 2422214 or +91 84591 41584, message us on WhatsApp, or use the appointment form. Please bring your previous reports and a list of the medicines you take.