MHMW

GMI calculator: glucose management indicator from CGM data

Glucose Management Indicator at a mean glucose of 150 mg/dLworked example

6.9%

Mean glucose used
150 mg/dL
ADA range for this figure
the range the ADA uses to diagnose diabetes

GMI estimates what an A1C would look like given your CGM mean glucose. It is not the same measurement as a laboratory A1C, and the two often differ — enter your lab value above to see the gap.

Glucose unit

GMI replaced the older term "estimated A1C" precisely because it is a different measurement from a lab A1C. If you want the other direction — a lab A1C turned into an average glucose — use the A1C calculator.

GMI estimates what an A1C would look like given your CGM mean glucose, using the equation GMI = 3.31 + 0.02392 x mean glucose from Bergenstal 2018. Enter your mean glucose and, optionally, your laboratory A1C to see the gap between them, which the paper treats as informative rather than an error.

  • Glucose Management Indicator (GMI) — GMI (%) = 3.31 + 0.02392 x mean glucose (mg/dL). Verified against Bergenstal et al., Diabetes Care 2018 (GMI and a laboratory A1C commonly differ in the same person; the paper reports that difference is often substantial and is itself informative rather than an error.)

Everything you type here is computed in your browser. Nothing you enter is stored on a server, sent anywhere, or shared — there is no account and no health data to leak.

Frequently asked questions

Is GMI the same as A1C?
No. GMI is calculated from CGM mean glucose; a laboratory A1C measures glycated hemoglobin. Bergenstal and colleagues introduced the term GMI in 2018 specifically to stop the CGM figure being called an "estimated A1C", because the two commonly differ in the same person.
How is GMI calculated?
GMI (%) = 3.31 + 0.02392 x mean glucose in mg/dL. A mean glucose of 150 mg/dL gives a GMI of about 6.9%.
Why is my GMI different from my lab A1C?
The 2018 paper found the difference is often substantial and varies between individuals. Factors include how red blood cells glycate in that person and the period each measure covers. The size and direction of your gap is a useful thing to raise with your clinician.
How much CGM data does GMI need?
The figure is only as good as the average behind it. A mean glucose from a short or patchy wearing period is not comparable to one from a continuous fortnight or more, so use the longest complete period your CGM reports.
Should I use GMI or A1C to track my glucose?
That is a decision for you and your clinician, not a calculator. What this tool can tell you is exactly what each number is and how far apart yours are.

Get a quarterly nudge to re-check your numbers

Four emails a year: a reminder to re-take your numbers, and what changed in the guidance behind these tools. No spam, unsubscribe any time.

Double opt-in: you will get one confirmation email and nothing else until you click it.

The next number

No body metric means much on its own. Here is what this one feeds into.

A1C calculatorTurn a lab A1C into an average glucose, in either unit.Glucose to A1C calculatorTurn a meter average into an A1C using the ADA equation instead.

Related calculators

A1C calculatorGlycemic markersGlucose to A1C calculatorGlycemic markers

Every formula on this page is listed with its source on the methodology page, and changes to any reference value are logged in the data changelog. Canonical URL: https://myhealthmywellness.com/gmi-calculator

We use cookies to improve your experience and analyze traffic. Analytics and ads only load after consent. Learn more