Background: Correlations between mean glucose and A1c vary among persons with T1D, with weaker associations in youth vs. adults. We investigated the relationships between mean glucose assessed by continuous glucose monitoring (CGM) and A1c according to pubertal stage in youth with T1D.

Methods: Mean glucose and percent of time in various glucose ranges (<70, 70-180, >250 mg/dL) were calculated using CGM data from the 4 weeks before A1c measurement in 107 youth, ages 8-17, with T1D. Glucose data were compared by pubertal stage (pre-pubertal: Tanner (T) 1, pubertal: T2-4, post-pubertal: T5) and A1c categories (<7.5%, 7.5-8.4%, ≥8.5%).

Results: Mean (±SD) ages for the pre-pubertal (64% male), pubertal (56% male), and post-pubertal (32% male) groups were 10.1±1.3, 12.9±1.4, and 15.9±1.6 years, respectively. For the entire sample, CGM glucose (196±29 mg/dL) and A1c (7.8±0.8%) were highly correlated (r=.71, p<.001). Overall and among youth with A1c ≥7.5% vs. A1c <7.5%, there were no differences in mean glucose, A1c, or % time in various glucose ranges according to pubertal stage (Table).

Conclusions: Pre-pubertal youth appear to have higher mean glucose than reflected by their A1c, particularly for those achieving A1c <7.5%, suggesting greater glycemic excursions in young children. Ideally, A1c should be interpreted in association with CGM data, particularly in young children, in efforts to optimize glycemia.


J. Zhu: None. L. Volkening: None. M. Katz: None. L.M. Laffel: Consultant; Self; Eli Lilly and Company, Novo Nordisk Inc., Sanofi US, MannKind Corporation, Roche Diagnostics Corporation, Dexcom, Inc., Insulet Corporation, AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Johnson & Johnson Diabetes Institute, LLC..

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