This document discusses diabetes mellitus (DM) in pregnancy. It notes that gestational diabetes mellitus (GDM) accounts for 90% of DM cases in pregnancy and is caused by the placenta producing hormones that cause insulin resistance. The prevalence of GDM is increasing worldwide due to lifestyle changes. Proper management of GDM and DM in pregnancy requires careful monitoring, medical nutrition therapy, exercise, glycemic control through medication or insulin, and timing of delivery to improve maternal and fetal outcomes.