OBJECTIVE

The glucose management indicator (GMI) is widely used as a replacement for HbA1c, but information in pregnancy is very limited. We assessed the accuracy of GMI and associations with pregnancy outcomes in type 1 diabetes.

RESEARCH DESIGN AND METHODS

We compared HbA1c, continuous glucose monitoring (CGM) metrics, GMI at 12, 24, and 34 weeks’ gestation and outcomes in 220 women from the CGM in pregnant women with type 1 diabetes (CONCEPTT) trial using logistic/linear regression and Bland-Altman plots.

RESULTS

GMI equations performed less accurately in pregnancy, with higher bias, especially in first and third trimesters. GMI and mean CGM glucose had equivalent predictive capability over pregnancy outcomes. GMI did not offer additional predictive capability over time-in-range (63–140 mg/dL; 3.5–7.8 mmol/L), time-above-range (>140 mg/dL; >7.8 mmol/L), and average CGM glucose concentrations.

CONCLUSIONS

GMI is not an accurate replacement for HbA1c in pregnancy in women with type 1 diabetes.

Graphical Abstract

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© 2025 by the American Diabetes Association
2025
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