Translating glycated hemoglobin A1c into time spent in glucose target range: A multicenter study.

ABSTRACT

BACKGROUND: Approximately 90% of children and adolescents with type 1 diabetes in Sweden use continuous glucose monitoring (CGM), either as real-time CGM or intermittently scanned CGM to monitor their glucose levels. Time in target range (TIT) is an easily understandable metric for assessing glycemic control. OBJECTIVE: The aim of this study was to examine the relation between TIT and hemoglobin A1c (HbA1c). SUBJECTS AND METHODS: Subjects were recruited from three diabetes care centers in Sweden. Glucose data were collected for 133 children and adolescents with type 1 diabetes through CGM using Diasend. Subjects with registration time over 80% were included in the analysis. HbA1c was collected from SWEDIABKIDS, the Swedish pediatric diabetes quality registry. TIT was defined as 3.9 to 7.8 mmol/L (70-140 mg/dL) and time in range (TIR) as 3.9 to 10 mmol/L (70-180 mg/dL). RESULTS: During the period of 60 days, 105 subjects provided complete data for analysis. Mean age was 12.2 (±3.3) years, mean HbA1c was 53.9 (±8.2) mmol/mol or 7.1% (±0.7%). Mean sensor glucose value was 8.6 (±1.3) mmol/L, mean coefficient of variation was 42.2% (±7.2%), mean TIT was 40.9% (±SD 12.2%), and mean TIR was 60.8% (±13.1%). There was a significant nonlinear relation between TIT during 60 days and HbA1c, R2 = 0.69. CONCLUSION: This study suggests a nonlinear relation between time spent in glucose target range and HbA1c. The finding implies that time spent in TIT could be a useful metric in addition to HbA1c to assess glycemic control.