Snapshot A 33-year-old G3P2 woman at 24 weeks gestation presents to the clinic for a routine prenatal visit. Fundal height measures 33 cm. She is scheduled for an oral glucose tolerance test due to her fetus being large for gestational age (see chart in image). Her 1-hour postprandial glucose level is 215 mg/dL, 2-hour postprandial glucose level is 185 mg/dL, and 3-hour postprandial glucose level is 146 mg/dL. Introduction Overview gestational diabetes mellitus is a condition characterized by glucose intolerance that is first recognized during pregnancy Epidemiology Prevalence occurs in approximately 6% of pregnant women in the US Risk factors obesity family history of diabetes mellitus maternal age > 30 having previously given birth to an infant weighing > 9 pounds polycystic ovary syndrome non-white race ETIOLOGY Pathophysiology ↑ hormones of pregnancy (i.e., estrogen, cortisol, and human placental lactogen) may ↑ risk of insulin resistance Presentation Symptoms asymptomatic in majority of cases increased thirst and ↑ frequency of urination Physical exam fetus size large for gestational age Studies Oral glucose tolerance test conduct a 1-hour 50 g oral glucose tolerance test measure venous plasma glucose after 1 hour perform at 24-28 weeks of gestation ≥ 140 mg/dL is considered abnormal conduct an oral 3-hour 100 g glucose tolerance test confirm abnormal test if any 2 of the following are present fasting glucose level > 95 mg/dL glucose level after 1 hour > 180 mg/dL glucose level after 2 hours > 155 mg/dL glucose level after 3 hours > 140 mg/dL Treatment Lifestyle strict adherence to a diabetic diet (eating healthy foods rich in vitamins, minerals, and fiber and adhering to regular mealtimes and moderate portion sizes) indications initial treatment aerobic exercise and resistance training indications initial treatment routine monitoring of fasting blood glucose and postprandial glucose levels indications initial treatment Medical insulin indications elevated blood glucose level despite lifestyle modifications metformin indications elevated blood glucose level despite lifestyle modifications glyburide indications elevated blood glucose level despite lifestyle modifications Complications Maternal complications ↑ risk of developing type II diabetes mellitus ↑ risk of developing cardiovascular disease Fetal complications perinatal mortality incidence 2-5% of babies born to mothers with gestational DM neonatal hypoglycemia ↑ amount of fetal insulin in the setting of a ↑ maternal glucose supply in utero ß-cell hyperplasia in the newborn congenital defects cardiac deformities secondary to trophic effect of insulin macrosomia (> 4500 g) shoulder dystocia during vaginal delivery