Time in Range (TIR) in Diabetes: How to Understand Your CGM Report

ByDr. Moxit Shah

Dr. Moxit Shah, DM Endocrinology | Vishuddha Diabetes, Thyroid, Weight Loss Clinic, Ahmedabad

If you use a continuous glucose monitor (CGM), your report can tell you more than the latest glucose number. One of its most useful measures is Time in Range (TIR)—the percentage of time your glucose stays within a target range. TIR helps you and your diabetes clinician understand daily patterns, including highs and lows that an HbA1c result alone may not show.

This guide explains what TIR means, which numbers to look at, how to interpret a CGM report, and when to discuss changes with your diabetes team. Targets must be individualized, especially for people at risk of hypoglycaemia, older adults, and those who are pregnant.

What is Time in Range (TIR)?

For many non-pregnant adults with diabetes who use CGM, the usual reference range is 70–180 mg/dL (3.9–10.0 mmol/L). TIR is the percentage of monitored time glucose remains inside that range.

For example, a TIR of 70% means glucose was within the range for about 16 hours and 48 minutes of a typical day. The remaining time may be spent above or below range, so TIR should always be read alongside the high-glucose and low-glucose metrics.

What TIR target should you aim for?

For many non-pregnant adults, international consensus targets used in the American Diabetes Association’s 2026 Standards of Care include:

  • Time in Range (70–180 mg/dL): more than 70% of the time.
  • Time below 70 mg/dL: less than 4% of the time.
  • Time below 54 mg/dL: less than 1% of the time.
  • Time above 180 mg/dL: less than 25% of the time.
  • Time above 250 mg/dL: less than 5% of the time.

These are reference goals—not a personal prescription. A less stringent TIR target may be safer for some older adults or people with complex health needs, particularly when avoiding hypoglycaemia is a priority. Pregnancy has different glucose targets and requires specialist guidance. Do not change medication doses just to reach a TIR number.

How is TIR different from HbA1c?

HbA1c reflects average glucose over roughly the previous two to three months. TIR shows how glucose moves through the day and night. Two people can have similar HbA1c results but very different patterns: one may have fairly steady glucose, while another has repeated highs after meals and lows overnight.

CGM reports may also show a Glucose Management Indicator (GMI), an estimate based on average sensor glucose. GMI is not the same test as laboratory HbA1c and the two values may differ. Your clinician interprets them with symptoms, medicines and other clinical information.

How much CGM data is useful?

A report based on about 14 days of data, with the sensor active for at least 70% of that period, is commonly used for pattern assessment. A shorter or incomplete period may not represent your usual routine. Illness, travel, unusual meals, missed medicines, exercise changes and sensor gaps can affect the picture.

Bring the full report or share it with your diabetes team rather than focusing on a single day or isolated spike.

Which parts of the CGM report should you review?

  • Time in Range: How much of the day is glucose within your agreed target range?
  • Time Below Range: Are there lows, particularly overnight, during exercise or when meals are delayed?
  • Time Above Range: Do high readings occur after specific meals, at certain times, or throughout the day?
  • Average glucose and GMI: What is the overall pattern, and does it fit with your HbA1c?
  • Glucose variability: Are readings relatively steady or frequently swinging up and down?
  • Daily pattern graph: At what times do highs and lows repeatedly occur?

The aim is to identify repeatable patterns that can guide a safe, practical treatment discussion—not to achieve a perfect-looking graph every day.

What can affect Time in Range?

Glucose patterns can be influenced by meal timing and composition, physical activity, sleep, stress, infections, hydration, medicine timing and dose, and changes in daily routine. Insulin and some other diabetes medicines can cause low glucose, especially when food intake or activity changes.

Keep a brief note of relevant events when reviewing a CGM report. For example, a repeated post-meal rise may prompt a discussion about meal portions, timing, or the prescribed treatment plan. Repeated overnight lows need prompt review, particularly if you use insulin or a sulfonylurea.

Can you improve TIR safely?

  • Take medicines according to the prescribed plan and discuss missed doses or side effects with your clinician.
  • Build regular meals that suit your needs; avoid extreme restriction or skipping meals when your treatment can cause hypoglycaemia.
  • Choose activity that is appropriate for your health and fitness, and learn how exercise affects your glucose.
  • Review recurring highs and lows with your clinician or diabetes educator.
  • Use CGM alerts as instructed and keep a blood glucose meter available when recommended.

If a sensor reading does not match how you feel, changes unexpectedly, or seems implausible, follow the device instructions and confirm with a finger-stick glucose meter when advised. Sensor glucose can lag behind blood glucose, particularly when levels are changing quickly.

When should you seek help?

Repeated glucose readings below 70 mg/dL, any severe low, recurring overnight lows, persistent marked hyperglycaemia, or large unexplained swings deserve a treatment review. Confusion, seizure, unconsciousness or inability to swallow during a suspected severe low is an emergency; someone who is unconscious should not be given food or drink by mouth.

If glucose is very high and you are unwell, or you have vomiting, abdominal pain, deep or rapid breathing, drowsiness, or positive ketones where testing is advised, seek urgent medical assessment. People with type 1 diabetes should follow their individual sick-day and ketone plan and should not stop basal insulin without medical direction. See our guide to Diabetes sick-day rules.

Who may benefit from CGM?

CGM can be especially useful for people using insulin, those at risk of hypoglycaemia, and others whose diabetes team believes sensor data will help guide care. It is not necessary for every person, and the best device and monitoring approach depend on treatment, access, comfort, preferences and clinical needs. A CGM report should be interpreted with education and follow-up—not used as a substitute for care.

Frequently asked questions

Does 70% TIR mean my diabetes is cured?

No. TIR is one measure of glucose control. It does not establish remission or mean that screening for eye, kidney, nerve or cardiovascular complications can stop.

Can I compare my TIR with another person’s?

Use your own agreed targets. Age, pregnancy, diabetes type, medicines, hypoglycaemia risk and other health conditions can change what is appropriate.

Should I change insulin based on the graph?

Do not make major or repeated dose changes without a plan from your diabetes team. If you have been taught a specific insulin-adjustment algorithm, follow that plan and seek advice when patterns fall outside it.

Key takeaway

Time in Range complements HbA1c by showing how glucose behaves across the day. Review TIR together with time below range, time above range, variability and your symptoms. The safest goal is an individualized pattern with fewer clinically important highs and lows—not simply the highest possible TIR.

Related diabetes resources

Medical references

Medical disclaimer: This article is for general education and does not replace individual medical advice. Glucose targets and treatment decisions should be personalized by your healthcare professional.

Dr. Moxit Shah, DM Endocrinology
Vishuddha Diabetes, Thyroid, Weight Loss Clinic
104-105, Elite Magnum, Bhuyangdev Cross Road, Opp. Utsav Elegance, Vardhmannagar Society, Ghatlodiya/Memnagar, Ahmedabad, Gujarat 380061
Phone: +91 99799 92797

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