What is time in range? How to read your percentage

Short answer: time in range is the share of your glucose values that fall inside your target range. With a finger-stick log it is simply readings in range ÷ all readings × 100.

1. How it is calculated

Say you logged 28 readings this week and 19 were inside your target range, 3 were below and 6 were above. Your time in range is 19 ÷ 28 = 68%, with 11% below and 21% above. Looking at below and above separately matters: the same 68% can hide very different weeks.

2. The range people usually quote

An international consensus for CGM data (Battelino et al., Diabetes Care, 2019) uses 70–180 mg/dL (3.9–10.0 mmol/L) as the target range for many adults with type 1 or type 2 diabetes, with separate targets for pregnancy and for higher-risk groups. Your own range may be different — use the numbers your care team gave you.

3. Finger-stick vs CGM

A CGM reads every few minutes, so its percentage really is time. A meter log only sees the moments you tested. If you mostly test fasting and before meals, your percentage leans toward those moments. Testing at a mix of times (including after meals and bedtime) gives a fairer picture.

4. Read the trend, not one day

A single day with few readings can swing a lot. Compare 7, 14, 30 or 90 days and look at fasting versus after-meal averages alongside the percentage. Bring those numbers to your care team rather than changing your treatment on your own.

How Dropvel helps

You set your own target range (with a separate high limit for after meals). Every entry is marked below, in or above, the home screen shows today's percentage in range, and the Trends tab shows below / in / above for 7, 14, 30 or 90 days with fasting and before/after meal averages — and puts it all in a PDF for your appointment.

This guide is general information, not medical advice. Your targets, medication and insulin doses are decided with your care team.

FAQ

Is time in range the same as A1c?

No. A1c reflects your average glucose over about 3 months. Time in range shows how much of the time (or how many readings) you were inside your target, so two people with the same A1c can have very different time in range.

What range should I use?

Use the range your care team gave you. Ranges differ for pregnancy, children, older adults and different treatments, so there is no single right number for everyone.

Why is my percentage different from my CGM report?

A CGM measures every few minutes, so its time in range covers the whole day. A finger-stick log only covers the moments you measured, so it is a share of readings, not of time.

← See Dropvel: a simple diabetes log with a PDF report for your doctor