Glucose infusion (D5W, lactated Ringer’s solution) is given to all patients in labor unless delivery is immediate, but care is taken to control the infusion at 125 mL/h unless the patient needs additional glucose for metabolic demands, in which case the glucose infusion is increased. It may be anticipated that women >160 kg in weight will require more glucose. Glucose-containing fluids should not be used for bolus prior to induction of conduction anesthesia. A bedside glucose reflectance monitor is used to follow glucose levels every 2-4 hours with the goal of maintaining levels at 70-95 mg/dL. In those requiring insulin, regular insulin (25 U/250 mL normal saline, giving a dilution of 0.1 U/mL) is given by continuous infusion at levels of 0.5-2 U/h.

Oxytocin is given for labor induction similarly to normal pregnancies. Continuous fetal heart rate monitoring is required with careful attention to decelerations. Fetal tolerance to intrauterine stress is limited in diabetic pregnancies. Early scalp pH or oxygen saturation monitoring is indicated if worrisome patterns persist. If fetal macrosomia is suspected, forceps should be used with great caution in the second stage and shoulder girdle dystocia anticipated. Additional personnel may be necessary at the time of delivery.

If repeat cesarean section or other indication for elective surgery occurs, the patient should be directed to take the evening insulin dose prior to surgery, but not her morning dose. Showering with a bacterial solution the night before delivery seems reasonable due to the increase in wound infections in this group. The patient is at increased risk of thromboembolic events due to decreased prostacyclin production by the platelets.

Breastfeeding is not affected by diabetes and is generally encouraged.

Prognosis

Women diagnosed with gestational diabetes have an increased risk of developing diabetes mellitus in the future. If they require insulin for their pregnancy, there is a 50% risk of diabetes within 5 years. If dietary control has been sufficient, a 60% risk of developing diabetes mellitus within 10-15 years still persists. However, evidence shows that lifestyle alteration may delay or entirely prevent the onset of diabetes. Thus these patients benefit from a reduction of their risk factors.

Postpartum, the patient should be placed back on an ADA diet (with increased soluble fiber and reduced fat). She should do a lifestyle assessment and attempt to keep her weight near ideal for her height. Weight reduction is generally necessary, and thus, if the patient is not breastfeeding, calories are reduced to 1200-1500 kcal with repeat dietary instruction, and the same calorie ADA diet is continued as the patient is breastfeeding. The caloric demand of breastfeeding increases with neonatal size but can reach 800-1200 kcal per day. Exercise equivalent to expend the energy is to run hard for 1 hour (900 kcal). It takes 3500 kcal expended to reduce weight by 1 pound! She should enter a regular exercise program.

All gestationally diabetic patients should have a 75-g 3-hour glucose tolerance approximately 6 weeks after pregnancy to evaluate for preexisting diabetes. It is important to individualize a prevention program for the 98% who will have a negative test. If the 1-hour value is high, it represents decreased insulin capacity, whereas an elevated 3-hour value reflects decreased insulin receptors. With an elevated 1-hour level, limiting simple sugars in the diet should become a lifetime goal. With an elevated 3-hour glucose value, weight loss with increased abdominal musculature should significantly reduce the increased risk of diabetes. Lipids should be evaluated in black and Hispanic patients because of a higher incidence of hypercholesterolemia in this group. This is particularly advisable prior to initiation of oral contraceptive agents. Preconception glucose evaluation should be discussed with the patient, and she should be encouraged to have an annual fasting glucose.

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