Persistence of Individual Variations in Glycated Hemoglobin: Analysis of data from the Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Randomized Trial

OBJECTIVE: To determine the individual persistence of the relationship between mean sensor glucose (MG) concentrations and hemoglobin A(1c) (A1C) from the Juvenile Diabetes Research Foundation Continuous Glucose Monitoring (CGM) Randomized Trial. RESEARCH DESIGN AND METHODS: MG was calculated using CGM data for 3 months before A1C measurements at 3, 6, 9, and 12 months for the CGM group and at 9 and 12 months for the control group. An MG-to-A1C ratio was included in analysis for subjects who averaged ≥4 days/week of CGM use. RESULTS: Spearman correlations of the MG-to-A1C ratio between consecutive visits 3 months apart ranged from 0.70 to 0.79. The correlations for children and youth were slightly smaller than those for adults. No meaningful differences were observed by device type or change in A1C. CONCLUSIONS: Individual variations in the rate of hemoglobin glycation are persistent and contribute to the inaccuracy in estimating MGs calculated from A1C levels.