GMI Calculator

Estimate Glucose Management Indicator (GMI) from average glucose using the published CGM-based equation.

Last updated on: March 30, 2026

Calculate GMI

Enter average glucose in mg/dL or mmol/L. The result will automatically show GMI and mean glucose in both units.

Clinical Significance

Glucose Management Indicator (GMI) is an estimated A1C-like metric derived from mean glucose, typically obtained from continuous glucose monitoring data.

It helps users compare sensor-derived average glucose with a familiar percent-based summary, while recognizing that GMI and laboratory HbA1c may not always match.

Formula and Example

Published GMI equation: GMI (%) = 3.31 + 0.02392 × mean glucose (mg/dL). A companion equation is also published for mmol/L input.

This calculator converts glucose as needed and shows the result together with mean glucose in both mg/dL and mmol/L for easier interpretation.

Example: a mean glucose of 154 mg/dL corresponds to a GMI of about 7.0%.

Reference Interpretation

Lower GMI Range: GMI below 5.7%. This falls below the commonly used prediabetes threshold, though GMI is not identical to laboratory HbA1c.
Intermediate GMI Range: GMI from 5.7% to 6.4%. This overlaps with the commonly used prediabetes HbA1c range, but sensor-derived GMI should be interpreted cautiously.
Diabetes-Range GMI: GMI from 6.5% to 7.9%. This overlaps with the commonly used diabetes HbA1c range, but GMI is an estimate rather than a laboratory diagnosis.
High GMI: GMI 8.0% or higher. This suggests high recent average glucose exposure and may warrant closer review of glycemic control and CGM patterns.

Clinical Notes

GMI is most useful when interpreted together with time in range, glucose variability, sensor wear time, and laboratory HbA1c when available.

  • GMI is derived from average glucose, often from CGM data.
  • GMI and laboratory HbA1c may differ meaningfully in some individuals.
  • Interpret alongside CGM wear duration, percentage of active sensor data, and glucose patterns.
  • Use GMI as a supportive metric rather than a stand-alone diagnostic tool.

This page has been medically reviewed by Dr. Khoulah Attia – PharmD, Immunology Specialist.

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