Time in range refers to the amount of time a person’s blood glucose levels remain within a specific target range. Your CGM will tell you what your time in range is every day.

Your diabetes team will work with you to determine your personal high and low levels for your target range and what your percentage goal for this range should be. As a guide, most people start at a glucose target range of 3.9 to 10 mmol/L

For people with type 1 or type 2 diabetes, it is recommended to aim for:

At least 70% of the day in 3.9-10 mmol/L (in-range)

Less than 4% of the day below 3.9 mmol/L (below-range)

Minimize time each day above 10 mmol/L (above-range)

Being in range 70% of the time equates to an HbA1c of about 53 mmol/mol. However, for some people, the target is greater than 50%, equating to an HbA1c of about 63 mmol/mol. Your diabetes team can discuss personal targets with you.

Why is time in range important?

Time in range is useful as it captures the daily variation in glucose levels that living with diabetes brings. HbA1c measures the average blood glucose over a two to three-month period; it doesn’t capture the time spent in various blood glucose ranges throughout the day.

The graphic below from DiaTribe illustrates the advantages of viewing time in range. Each graph represents a different person but they all share the same HbA1c of 53 mmol/mol (average blood glucose of 8.6 mmol/L).

The first graph shows the person has a rollercoaster of dangerous highs and lows, the second still has highs and lows but much less pronounced and more time in range, the third has little variability and spends all the time in range.

Although HbA1c doesn’t give you an understanding of what your blood glucose levels are doing day by day, it’s an effective way of measuring your risk of getting diabetes complications from high glucose levels.  

So using time in range together with HbA1c is a good way for your healthcare team to review your diabetes care to help you reduce your risk of long-term health problems.