97-OR: Relationship between Time-in-Range and Laboratory HbA1c in Pregnant Women with Type 1 Diabetes Mellitus

Aims: To investigate the relationship between time-in-range (TIR) and laboratory glycated hemoglobin A1c (HbA1c) in pregnant women with type 1 diabetes mellitus (T1DM). Methods: An observational study enrolled pregnant women with T1DM who wore continuous glucose monitoring (CGM) system devices (iProTM2 system) in the first, second, third trimesters and postpartum from 11 hospitals in China from January 2015 to June 2018. Data derived from the CGM system were used to calculate TIR, time above range (TAR), time below range (TBR), mean glucose (MG), and glycemic variability (GV) parameters. Relationships were explored between the CGM metrics and HbA1c. Linear and curvilinear regressions were conducted to investigate the best-fitting model to account for the influence of gestational changes in HbA1c on the TIR- HbA1c relationship. Results: A total of 272 CGM data and corresponding laboratory HbA1c from 98 pregnant women with T1DM, as well as demographic and clinical characteristics were analyzed. Mean HbA1c and TIR were 6.49±1.29% and 76.16±17.97% during pregnancy, respectively. HbA1c was moderately correlated with TIR3.5-7.8(R=-0.429, P=0.001), mean glucose (R= 0.405, P=0.001) and the TAR7.8 (R=0.435, P=0.001), but was weakly correlated with TBR3.5 (R=0.034, P=0.001) during pregnancy. On average, a 1% (11 mmol/mol) difference in HbA1c corresponded to an 8.5% difference in TIR3.5-7.8. During pregnancy, HbA1c of 6%, 6.5% and 7% were equivalent to a TIR3.5-7.8 of 78%, 74%, and 69%, respectively. Conclusions: We found a moderate correlation between HbA1c and TIR3.5-7.8 during pregnancy. To achieve the HbA1c target 78% (18h 43min/per day), during pregnancy. Disclosure P. Ling: None. J. Weng: None. C. Wang: None. D. Yang: None. S. Luo: None. X. Zheng: None. J. Lv: None. J. Yan: None. W. Xu: None. B. Yao: None. Funding National Health and Family Planning Commission of the People’s Republic of China; Foundation for Public Welfare Industry Research Project (201502011); National Key Research and Development Program of China (2017YFC1309600); National Natural Science Foundation of China (81941022)