There is a fundamental gap in understanding the maternal and neonatal effects of antenatal corticosteroid (ACS) administration in women with threatened preterm birth (PTB) who have diabetes. Since the initial discovery of ACS for neonatal benefit in 1972, more than 40 randomized controlled trials have been performed evaluating its efficacy. However, none of these trials have included women with T2DM, and there is limited data among women with gestational diabetes. While ACS have been shown to reduce neonatal morbidity associated with PTB in non-diabetic women, the side effects of ACS (maternal hyperglycemia and fetal hyperinsulinemia) may mitigate the neonatal benefit of ACS in women with diabetes. Before neonatal benefit of ACS can be evaluated in this population, the first step is to optimize maternal glycemic control after ACS. Previous studies evaluating maternal hyperglycemia after ACS have been limited by small sample size, retrospective study design, or insufficient glucose data. Use of continuous glucose monitoring (CGM) in a randomized clinical trial provides a unique opportunity to overcome these challenges. Our long-term goal is to improve maternal and child health among women with diabetes as an independently funded clinical researcher. The research objectives of this proposal are to test the efficacy of three treatment strategies at achieving maternal glycemic control after ACS and evaluate the association between maternal glycemic control and neonatal outcomes. Our central hypothesis is that treatment with a continuous insulin infusion will improve maternal glycemic control, which is key to improving neonatal outcomes, but at the cost of less patient satisfaction and more health resource utilization. This hypothesis will be tested by pursuing the following specific aims: 1) Test the efficacy of three treatment strategies (addition of sliding scale insulin, up-titration of home insulin, and continuous insulin infusion) at achieving maternal glycemic control after ACS and 2) Quantify the association between maternal glycemic control after ACS and neonatal morbidity. Completion of these aims will determine the optimal strategy to achieve maternal glycemic control after ACS and inform a larger, multicenter trial to improve neonatal outcomes among women with diabetes and threatened PTB.