Differences Between Glycated Hemoglobin and Glucose Management Indicator in Real-Time and Intermittent Scanning Continuous Glucose Monitoring in Adults With Type 1 Diabetes.

BACKGROUND

This study demonstrates the difference between glucose management indicator (GMI) and glycated hemoglobin (HbA) according to sensor mean glucose and HbA status using 2 continuous glucose monitoring (CGM) sensors in people with type 1 diabetes.

METHODS

A total of 275 subjects (117 Dexcom G6 [G6] and 158 FreeStyle Libre 1 [FL]) with type 1 diabetes was included. The G6 and FL sensors were used, respectively, over 90 days to analyze 682 and 515 glycemic profiles that coincide with HbA.

RESULTS

The mean HbA was 6.6% in Dexcom G6 and 7.2% in FL profiles. In G6 profiles, GMI was significantly higher than HbA irrespective of mean glucose (all < .001, mean difference: 0.58% ± 0.49%). The GMI was significantly higher than the given HbA when HbA was below 8.0% (all < .001). The discordance was the highest at 0.9% for lower HbA values (5.0%-5.9%). The proportion of discordance >0.5% improved from 60.1% to 30.9% when using the revised GMI equation in G6 profiles. In FL profile, the overall mean difference between GMI and HbA was 0 ( = .966). The GMI was significantly lower by 0.9% than HbA of 9.0% to 9.9% and higher by 0.5% in HbA of 5.0% to 5.9% (all < .001).

CONCLUSIONS

The GMI is overestimated in G6 users, particularly those with well-controlled diabetes, but the GMI and HbA discordance improved with a revised equation from the observed data. The FL profile showed greater discordance for lower HbA levels or higher HbA levels.