What are the recommended methods of induction and insulin protocol for managing pregestational diabetes (diabetes diagnosed before pregnancy) during labor?

Management of Pregestational Diabetes During Labor: Induction Methods and Insulin Protocol

For women with pregestational diabetes, intravenous insulin infusion during labor is strongly recommended to maintain optimal glycemic control, with target blood glucose levels of 70-100 mg/dL (3.9-5.5 mmol/L) to reduce the risk of neonatal hypoglycemia. 1

Induction Methods

• Standard obstetrical indications for induction apply to women with pregestational diabetes, with delivery recommended by 38-39 weeks' gestation to balance the risk of stillbirth against neonatal complications 2
• Pregestational diabetes alone is not an indication for cesarean delivery, but careful consideration should be given to estimated fetal weight, especially if >4500g due to increased risk of shoulder dystocia 2
• Fetal surveillance should be intensified during the last 8-10 weeks of pregnancy with weekly antenatal testing reasonable after 32 weeks 2
• Earlier delivery may be indicated in cases of maternal or fetal compromise, including poor glycemic control, hypertensive disorders, abnormal fetal testing, or evidence of fetal growth restriction 2

Insulin Protocol During Labor

Pre-labor Phase

• Continue the patient's regular diabetes treatment regimen with the same glycemic targets used during pregnancy (fasting <95 mg/dL and either one-hour postprandial <140 mg/dL or two-hour postprandial <120 mg/dL) 3
• Monitor blood glucose levels frequently to maintain optimal control 3

Active Labor Phase

• For Type 1 and Type 2 diabetes patients: Switch from subcutaneous insulin to intravenous (IV) insulin infusion during active labor 3
• For patients using insulin pumps: It is preferable to change to IV insulin treatment, though retention of the insulin pump is possible with a personalized protocol for adaptation of pump output during labor 3
• Target blood glucose range: 70-100 mg/dL (3.9-5.5 mmol/L) 1
• Monitoring frequency: Check capillary blood glucose hourly and adjust insulin infusion rates accordingly 4
• Concurrent glucose infusion: Administer 10% glucose infusion alongside insulin to avoid maternal hypoglycemia and ketosis due to fasting and increased energy demands during active labor 3
• For Type 1 diabetes patients: Never interrupt insulin therapy due to high risk of ketosis, even with only moderately elevated blood glucose levels 3

Specific IV Insulin Protocol

• Use a standardized algorithm based on maternal insulin requirements to drive real-time maternal glucose control 5
• Software-guided insulin dosing systems (like GlucoStabilizer) have been shown to be superior in achieving target glucose values at delivery (81.8% vs 9.1% with standard insulin dosing charts) without increasing maternal hypoglycemia 1
• Monitor for hypokalemia, as IV insulin can stimulate potassium movement into cells, potentially leading to hypokalemia that could cause respiratory paralysis, ventricular arrhythmia, or death if left untreated 6

Immediate Postpartum Management

• Insulin requirements decrease dramatically immediately after delivery 7
• For Type 1 diabetes: Resume the basal-bolus insulin scheme with a significant reduction in dosage - either 80% of pre-pregnancy doses or 50% of the doses used at the end of pregnancy 3, 7
• For Type 2 diabetes: Continue insulin at half-dose while awaiting diabetologist advice 3
• Target blood glucose range: 6-8.8 mmol/L (110-160 mg/dL) after vaginal delivery, with slightly lower targets after cesarean section to support wound healing 3, 7
• Never discontinue basal insulin in Type 1 diabetes patients due to high risk of ketoacidosis 7
• Be vigilant for hypoglycemia, especially during breastfeeding and with irregular sleep patterns 7

Common Pitfalls and Caveats

• Failure to monitor blood glucose frequently during labor can lead to maternal hyperglycemia and subsequent neonatal hypoglycemia 4, 1
• Interruption of insulin therapy in Type 1 diabetes patients can rapidly lead to ketoacidosis 3, 7
• Excessive insulin dosing in the immediate postpartum period can cause severe hypoglycemia, as insulin requirements drop dramatically after placental delivery 7
• Inadequate glucose infusion during labor can lead to maternal hypoglycemia and ketosis 3
• Lack of potassium monitoring during IV insulin administration can lead to dangerous hypokalemia 6