What is Time in Range?
Time in range is the proportion of readings within a defined glucose interval. Consensus recommends over 70% in 70–180 mg/dL for many nonpregnant adults with type 1 or type 2 diabetes, individualized with their care team. Time below range, time above range and variability add information that TIR alone does not supply. CGM provides dense sampling, but TIR has also been studied using seven-point fingerstick profiles; it does not replace laboratory HbA1c.
TIR summarizes time in one interval. It does not by itself distinguish time below from time above range or fully describe variability; inspect complementary metrics and the actual trace.
Consensus recommends more than 70% in 70–180 mg/dL for many nonpregnant adults with type 1 or type 2 diabetes, individualized with the care team. In a study of 153 healthy people without diabetes aged 7–80, the median time in 70–140 mg/dL was 96% (interquartile range 93–98%); these are observed reference values, not a medical target (Shah et al., J Clin Endocrinol Metab 2019).
TIR complements laboratory HbA1c
Laboratory HbA1c reflects roughly three months of glucose exposure, with recent glucose, especially the last 30 days, contributing more. It can change before three months. GMI and time in range are complementary metrics, not replacements for laboratory testing. People with similar averages can have different distributions, but TIR alone is not a complete description of either distribution.
TIR correlates with complications. In an analysis of the Diabetes Control and Complications Trial (1,440 people with type 1 diabetes), time in range 70–180 mg/dL was estimated from seven-point fingerstick glucose profiles; each 10-percentage-point lower time in range was associated with a 64% higher hazard of retinopathy progression and a 40% higher hazard of microalbuminuria (Beck et al., Diabetes Care 2019). This is an observational association in type 1 diabetes, not a measure of absolute risk.
Laboratory HbA1c reflects roughly three months of glucose exposure, with recent glucose, especially the last 30 days, contributing more. It can change before three months. GMI and time in range are complementary metrics, not replacements for laboratory testing. Changes in TIR do not automatically show a treatment benefit; interpret the reporting window, data coverage and clinical context.
How to improve your Time in Range
Review time above and below your individualized range with your care team. Do not assume every low is an artifact or prioritize food substitutions over safety instructions.
Post-meal walks. In one small randomized crossover study of 41 adults with type 2 diabetes, a 10-minute walk after each main meal lowered the glucose rise in the three hours after meals (incremental area under the curve) by about 12% overall and by about 22% after the evening meal, compared with one 30-minute walk per day (Reynolds et al., Diabetologia 2016; the percentages are calculated from the reported ratios 0.88 and 0.78, and the comparison is against another walking pattern, not against no walk).
Meal timing and glucose responses vary. No universal breakfast change is established here as the fastest way to improve TIR.
Improve sleep quality. In a small controlled study, one night of four hours of sleep reduced insulin sensitivity in healthy adults the next day (Donga et al., 2010). Whether better sleep improves your own time in range is something you can look for in your data; it is not guaranteed.
Frequently asked questions
Sources & Further Reading
This article draws on the following clinical sources:
- Battelino et al. Clinical Targets for Continuous Glucose Monitoring Data Interpretation. Diabetes Care 2019. PubMed →
- Beck et al. Validation of Time in Range as an Outcome Measure for Diabetes Clinical Trials. Diabetes Care 2019. PubMed →
- American Diabetes Association. Time in Range as a Quality Metric. Diabetes Care →