Supplemental materials: Basal Hyperglycemia Contributes More Than Fifty Percent to Time in Range in Pregnant Women with Type 1 Diabetes

This is a study to evaluate the relative contribution of basal hyperglycemia (BHG) and postprandial hyperglycemia (PHG) to the time in range (TIR) categories in pregnant women with type 1 diabetes mellitus (T1DM). This observational study included pregnancies with T1DM from the CARNATION study who wore continuous glucose monitoring (CGM) devices during pregnancy. The data from CGM were analyzed for TIR (range, 3.5-7.8 mmol/L), areas under the curve (AUC) of PHG, AUC of BHG, and basal and postprandial hyperglycemia contribution rates. The contribution rates of BHG and PHG to the different levels of TIR(＜60%, 60-78%,≥78%) were analyzed. A total of 112 pregnant women with T1DM with 295 CGM-HbA1c profiles were enrolled in this study. The participants' average age was 28.8±3.9 years with a diabetes duration of 8.4±6.2 years. All women experienced a mean TIR of 75.6±19.0% and a mean HbA1c of 6.2±1.1% during pregnancy. The BHG contribution accounted for 74.9(36.8, 100)%, 69.2(13.4, 100)%, and 66.5(10.0, 100)% (P＜0.001) and PHG accounted for 25.1(0, 6.2)% and 30.8(0, 86.6)% and 33.6(0, 90.0)% (P＜0.001) when participants experienced the TIR＜60%, 60-78%,≥78%, respectively. In conclusion, basal hyperglycemia was the major contributor to TIR during pregnancy. Along with controlling the postprandial hyperglycemia, pregnant women with T1DM who did not reach the target of TIR may benefit more from the optimization of insulin regimens focusing on reducing basal glucose.