608-P: Relationship between Time-in-Range and Estimated HbA1c Derived from Continuous Glucose Monitoring System in Adults with Type 1 Diabetes Mellitus

Aims: Time-in-range (TIR) and estimated glycated hemoglobin (eHbA1c), two key metrics derived from continuous glucose monitoring system (CGMS), are valuable for glycemic control. This study is to investigate the relationship between TIR and eHbA1c, and the impact of glycemic variability on their relationship. Methods: The CGMS data were collected from baseline and follow-up visits in a clinical trial (NCT03522870) and yearly visits in the Guangdong Type 1 Diabetes Translational Medicine Study. Adult patients with type 1 diabetes (≥18 yrs) who had available CGM data for > 3 days were included. Correlation between TIR and eHbA1c was explored according to different stratification of glycemic variability assessed by glucose coefficient of variation (CV). Predicted TIR in the fixed eHbA1c value was calculated via the linear regression equations performed in the respective interquartile group of CV. Results: From March 2014 to July 2020, a total of 260 CGMS data were collected. The mean wearing time of available CGM data was 11.8±3.8 days, and the mean value of TIR, eHbA1c, and CV was 62.9±14.1%, 7.2±0.8%, and 39.4±8.1%, respectively. There was a strong negative correlation between TIR and eHbA1c (R=-0.83, P