What is the GMI formula?

GMI (%) = 3.31 + 0.02392 x mean glucose (mg/dL). For mmol/L: GMI (%) = 3.31 + 0.4308 x mean glucose (mmol/L). GMI is derived from a regression analysis of CGM mean glucose against HbA1c in over 1,000 subjects.

Why is GMI preferred over eAG for CGM users?

GMI is directly derived from CGM data and reflects actual glycemic exposure over the sensor wear period (typically 14 days). It correlates better with HbA1c than the older eAG formula and accounts for glucose variability patterns.

What is the clinical significance of GMI vs laboratory HbA1c?

GMI and lab HbA1c often differ by 0.5% or more for the same patient. This discordance indicates abnormal red cell lifespan, hemoglobin variants, or post-translational modifications affecting glycation. Neither is uniformly superior.

Glucose Management Indicator (GMI)

Convert CGM mean glucose to estimated HbA1c: GMI = 3.31 + 0.02392 x mean glucose (mg/dL). More accurate than eAG formula for CGM time-in-range assessment.

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Frequently Asked Questions

What is the GMI formula?

Why is GMI preferred over eAG for CGM users?

What is the clinical significance of GMI vs laboratory HbA1c?