Glucose Management Indicator (GMI)

The Glucose Management Indicator, or GMI, estimates what your HbA1c blood test result would likely be, based on the glucose readings stored in this app. It lets you track your long-term glucose control between doctor visits.

How It Works

The formula uses your average glucose level over all stored readings:

GMI = 3.31 + (0.02392 × average glucose in mg/dL)

For example, if your average glucose is 115 mg/dL: GMI = 3.31 + (0.02392 × 115) = 3.31 + 2.75 = 6.06%

The GMI is expressed as a percentage, just like HbA1c. The app needs at least 14 days of readings before it will display a GMI, because fewer readings produce unreliable estimates.

Your Target

• Below 5.7% — Normal range
• 5.7% to 6.4% — Prediabetic range (this is where you want to be moving downward)
• 6.5% and above — Diabetic range

For prediabetes management, a GMI below 5.7% is the goal. Even moving from 6.2% to 5.9% is meaningful progress.

Why This Matters

Your HbA1c lab test reflects your average glucose over roughly three months, but you can only get it done every few months. GMI gives you a real-time estimate so you can see the direction you are heading right now, not just at your next appointment. Studies show GMI correlates closely with laboratory HbA1c results, though the two values can differ by up to 0.3–0.5% in some individuals.

What You Can Do

• GMI is an estimate — always confirm with a real HbA1c lab test, especially before making any medical decisions.
• If your GMI is creeping up over weeks, it is an early warning sign to review your diet and activity level before your next lab appointment.
• Adding more readings spread across different times of day will make your GMI more accurate.
• A drop of 0.5% in GMI corresponds roughly to an average glucose reduction of about 20 mg/dL — small consistent improvements add up.

Based on: Bergenstal et al., Diabetes Care 2018; American Diabetes Association Standards of Care 2023