What is the preferred first-line treatment for gestational diabetes not controlled by lifestyle modification?

The preferred first-line treatment for gestational diabetes that is not controlled by lifestyle modifications is insulin. Insulin therapy is considered the most effective method for managing elevated blood glucose levels in pregnant women. This is largely due to its ability to quickly lower blood sugar levels without crossing the placenta and affecting the fetus, which is a critical consideration during pregnancy.

Insulin's flexibility in dosage adjustments, its ability to mimic physiological insulin secretion, and the lack of significant teratogenic effects make it the treatment of choice when dietary changes and lifestyle modifications are insufficient. While metformin and sulfonylureas are options that may be used in certain circumstances, they are generally not preferred as first-line treatments because of concerns regarding their safety profiles during pregnancy and their less favorable side effects compared to insulin. Dietary changes can help manage gestational diabetes initially, but when they do not adequately control the condition, transitioning to insulin therapy is necessary for ensuring both maternal and fetal health.