Estimating Insulin Sensitivity in Pregnancies With Type 1 Diabetes

The investigators want to learn how the body's response to insulin changes during pregnancy in people with Type 1 Diabetes. In this study, the investigators will look at information from people who used a Dexcom continuous glucose monitor (CGM) and a Tandem insulin pump while they were pregnant. Participants will fill out an online survey and agree to share their device data. The investigators will use this information to see how insulin sensitivity changes from three months before pregnancy to six months after the baby is born.