Labor and Delivery of the Patient with Diabetes
The goal is for the patient with diabetes to deliver a healthy child vaginally. The adequacy of glucose control, the well-being of the infant, estimated fetal weight by ultrasound, presence of hypertension or other complications of preg-nancy, gestational age, presentation of the fetus, and status of the cervix are all factors involved in decisions re-garding delivery. In the well-controlled patient with diabeteswho has no complications, induction at term (38 to 39 weeks) is often undertaken. For women with GDM or pregesta-tional diabetes and an estimated fetal weight of 4500 g or more, caesarean delivery may be considered. If an earlier delivery is deemed necessary for either fetal or maternal indications, fetal maturity studies may be performed on amniotic fluid obtained by amniocentesis. If antepartum steroids for fetal lung maturity become necessary (e.g., for patients with preterm labor), frequent glucose monitoring and, at times, increased doses of insulin are necessary to counter the hyperglycemic effects of corticosteroids.
Whether the patient’s labor begins spontaneously or is in-duced, the goal of intrapartum insulin therapy is strict glucose con-trol. Once active labor begins or glucose levels decrease to70 mg/dL, a constant glucose infusion of a 5% dextrose solution delivered at a rate of 100 to 150 mL/hr is adminis-tered to maintain a glucose level of 100 mg/dL. The plasma glucose level should be assessed every 1 to 2 hours. Short-acting insulin may be administered, usually by constant intravenous infusion, if glucose levels exceed 100 mg/dL.
With delivery of the placenta, the source of the “anti-insulin” factors, most notably hPL, is removed. With its short half-life, the effect on plasma glucose is evident within hours. Many patients do not require any insulin for a few days postpartum. Routine management generally consists of frequent glucose assessments and a sliding scale approach with minimal insulin injections. The goals for optimal glu-cose values are less stringent in the puerperium than dur-ing pregnancy. For patients with gestational diabetes, no further insulin is required postpartum. In patients with pregestational diabetes, insulin is generally resumed at 50% of the pre-pregnant dose once a patient is consum-ing a normal diet. Thereafter, insulin can be adjusted over the ensuing weeks, with requirements usually reaching the pre-pregnancy level.
More than 95% of mothers with gestational diabetes return to a completely normal glucose status immediately postpartum; however, approximately 50% of these women go on to develop type 2 diabetes later in life and need to be educated about the importance of maintaining a healthy diet and regular exercise program. Glucose tolerance screen-ing is advocated 2 to 4 months postpartum to detect the 3% to 5% who remain diabetic and require treatment. Typically,such screening involves a 75-g glucose load, followed by plasma glucose determination 2 hours later. A value above 140 mg/dL requires follow-up.
For contraception, barrier methods or intrauterine contraceptives are often chosen; patients who choose oral contraceptives should monitor their glucose values to iden-tify an increase that is sometimes seen with this method.