A 29-Year-Old Woman, Gravida 1 Para 0, at 26 Weeks

A 29-year-old woman, gravida 1 para 0, at 26 weeks gestation comes to the office for a routine prenatal visit.  She reports no contractions, vaginal bleeding, or leakage of fluid.  There is good fetal movement.  The patient has a history of polycystic ovarian syndrome.  This pregnancy was conceived through ovulation induction but has otherwise been uncomplicated.  She has no other chronic medical conditions or previous surgeries.  The patient walks for 30-45 minutes 5 days a week.  She takes prenatal vitamins and folate supplementation daily.  She does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 130/80 mm Hg and pulse is 89/min.  BMI is 27 kg/m².  Fetal heart tones are 150/min.  Fundal height is 28 cm.  Third-trimester laboratory results are as follows: The appropriate evaluation is completed and the patient is diagnosed with gestational diabetes mellitus.  She is started on a diabetic diet and continues to exercise regularly, with an hour of brisk walking on most days.  The patient returns 3 weeks later for a routine prenatal visit and for evaluation of her glycemic control.  She reports compliance with her diet and checks her fasting and post-prandial blood glucose values daily.  Blood pressure is 136/70 mm Hg and pulse is 80/min.  Fetal heart tones are 140/min.  During the third week of the patient's regimen, fasting blood glucose values are 100-110 mg/dL, and 2-hour post-prandial glucose values are 122-158 mg/dL.  Which of the following is the most accurate?

A) Diet and exercise are controlling the patient's blood sugar
B) Glipizide should be started to reduce the risk of neonatal hypoglycemia
C) Insulin should be started to reduce the postpartum risk of type 1 diabetes mellitus
D) Insulin should be started to reduce the risk of shoulder dystocia
E) Metformin should be avoided as it is less effective than insulin