Diabetes V: Intrapartum and Postpartum Glucose Management

Great! Your patient is here in labor or for induction… now what?

• Glycemic goals - why do we have them and what are they? 

• Why do we have them? 

• It is a good idea to avoid hyperglycemia in labor due to risk of fetal hypoxemia and neonatal hypoglycemia 

• Fetal hypoxemia 

• Some evidence that fetal hypoxia can result from diabetes with uncontrolled blood sugars 

• Also increased blood sugars that lead to ketoacidosis can increase fetal acidosis and hypoxia 

• Neonatal hypoglycemia 

• Increased maternal blood sugars increases fetal production of insulin 

• High levels of insulin after delivery with no exposure to maternal blood sugar → hypoglycemia and NICU admission 

• What are they? 

• Initially, there was recommendation by ACOG that blood sugar be between 60 -100 mg/dL

• However, there was a study that showed that tight control maternal control did not results in better initial neonatal glucose concentrations compared to a more liberalized management strategy 

• Hamel H et al 2019, Obstet Gynecol: https://pubmed.ncbi.nlm.nih.gov/31135731/

• The goals can be different depending on your institution, but based on the above study, the goal is to be between 60 - 120 mg/dL 

• Based on ACOG’s Practice Bulletin, goal should be <110 mg/dL 

• How often should we monitor blood sugar? 

• ACOG recommends checking blood sugar levels q1 hour in active labor 

• If not on an insulin drip and during labor, please follow the protocol at your hospital, as certain hospitals have adopted a more liberalized form of glucose management 

• One example of protocol: 

• If not in active labor, can check blood sugar every 4 hours 

• In active labor, can check every 2 hours, but if needs treatment → recheck in 1 hour after treatment 

• If we follow Hamel et al’s protocol, the plan is to check every 4 hours, but to check more frequently if treatment is needed 

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Example protocol - acog practice bulletin, pregestational diabetes mellitus

Treating Hyperglycemia

• Use insulin! 

  • Coming in for scheduled induction/cesarean: we usually ask patients to take half the dose of long acting insulin.

  • Example: patient is on 20 NPH during the day and 40 NPH at night. They are coming in for a 7 am induction and will not be eating much during labor 

  • Patient should be instructed to take 40 NPH the night prior (to help with fasting), and can be given or should take 10 u NPH that morning, as patient likely will not be eating much during the day they are being induced 

  • Do not take short acting insulin the day of if patient is not eating 

  • In patients who come in laboring:

  • Ask patients what insulin they have taken that day 

  • If still in labor and time for long acting insulin, if patient is not eating, can plan for half of the long acting insulin 

  Ok, so that takes care of long acting insulin, but what if the patient is having elevated blood sugars during labor? 

• Short acting insulin 

• If a patient is having elevated blood sugars above protocol, they can be given short acting insulin to bring down their blood sugars 

• How much to give: 

• This will come down to the patient, but this is a good time to remember the rules we taught you before! 

• Type 1s: use the rule of 1800: 1800 / TDD insulin (units) = expected ICF

• Type 2/GDM: use the rule of 1500: 1500 / TDD insulin (units) = expected ICF

1. So if I’m taking 50 units total of insulin per day, as a T2DM/GDM I would have a correction factor of 30 - meaning 1u of insulin would bring my blood sugar down about 30 mg/dL

2. This is helpful for the floor - if you need to cover someone, knowing their total daily insulin dose (or approximating using their weight) can help you provide more reliable amounts of insulin. 

• You may also have protocols within your hospital with certain types of sliding scales 

• Insulin drip 

• Who needs an insulin drip? 

• Patients whose blood sugars are difficult to control 

1. Very high blood sugars (>200 mg/dL) 

2. Those who require multiple treatments with short acting insulin (> 2 times, usually)

3. Those who have an insulin pump that cannot be used in the hospital 

• How do I manage an insulin drip? 

• Most of the time, insulin drips should be co-managed either with endocrinology or with MFM - so ask for help! 

• We cover this in our episode for diabetic ketoacidosis!

• As a brief overview: the insulin in a drip is usually regular or rapid-acting insulin 

1. Most of the time, if the blood sugar is <200mg/dL, there is a protocol in the hospital to follow for labor 

2. Can usually start at 1-1.5u/hr, but if patient is in DKA or has very high blood sugars, can also start at 0.1u/kg/hr or even first start with a bolus of 0.1u/kg 

• Blood sugar should be checked every hour and insulin drip can be adjusted up and down by 1u/hr depending on blood sugar control 

• Hypoglycemia - Low blood sugars 

• If patient is not eating or patients with T1DM, they will need to placed on some form of dextrose so that they do not go into DKA; pregnant patients are also more likely to be in euglycemic DKA 

• Again, there is usually a protocol in the hospital, but these patients should be placed on D5NS if not eating and in active labor or if blood sugar drops <70 mg/dL 

• These can follow the usual maintenance fluid calculations, using the 4-2-1 formula for how much fluid is needed per hour 

• 4 mL/kg/hr for the first 10 kg 

• 2 ml/kg/hr for the second 10 kg 

• 1 ml/kg/hr for the remainder 

• Example 

• For a patient who weighs 70kg: 

1. 40 ml/hr (4*10) + 20 ml/hr (2*10) + 50 ml/hr (1*50) = 110 ml/hr 

• Another method to calculate is 2.5mg of dextrose/kg/min 

• For everyone who is getting insulin, you should order an as needed D50 injection or D25 injection depending on what your hospital has 

• This is in the event of acute hypoglycemia or who may be unresponsive and not able to take PO 

• If someone is able to take PO, you should follow the 15/15 rule: basically, consume 15g of glucose and check blood sugar in 15 minutes 

• Usually 3 glucose tablets 

• Approximately 4 oz of regular juice or soda

Let’s say we get our patient through labor and birth … what about the postpartum period? 

• Insulin requirements postpartum 

• Insulin requirements go down significantly postpartum, especially if the patient is breastfeeding 

• If the patient was on insulin prior to pregnancy, they should return to their prepregnancy insulin regimen 

• If patients were not on insulin, but were diagnosed with T2DM during their pregnancy, then during recovery in the hospital, our general recommendation depends on pre-pregnancy or early pregnancy A1C 

• For T2DM, patients with A1C > 9.0%, they should generally stay on insulin 

• If <9.0%, then can have discussion with endocrinology and MFM to try oral medications, and would need to be safe during breastfeeding if patient desires to breastfeed 

• Hopefully this plan was made as an outpatient! 

• General consensus for continuing insulin is to half their long acting insulin and then put them on a sliding scale 

• After approximately 24 hours, calculate how much sliding scale they needed, and this can be turned into short acting insulin if needed 

• Consult endocrinology and MFM for guidance, and also make sure patient has endocrinology or PCP follow up 

Gestational Diabetes Trio, Featuring A Special Interview with Dr. Donald Coustan

Happy Holidays to all, and to celebrate the season we have a very sweet triple episode release today! The first two episodes are focused on the pathophysiology, diagnosis, and treatment of GDM, while the third is a special interview with Dr. Donald Coustan, Professor and Chair Emeritus of the Department of Obstetrics and Gynecology at Brown University. Dr. Coustan was recently profiled by AJOG as a “Giant in Obstetrics and Gynecology.” We hope you enjoy the interview and his perspective on GDM and OB-GYN more generally.

The ACOG PB (PB 190) on GDM was recently updated in February 2018. There is also a new bulletin on Pregestational Diabetes (PB 201), though we don’t spend much time on pregestational diabetes today.

We discuss multiple ways to diagnose GDM, based on different organization’s recommendations. The classic Carpenter-Coustan criteria endorsed by ACOG and the National Diabetes Data Group (NDDG) are based on two-step testing. An initial 50 gram glucose tolerance test is performed, and patients move on to the second screen if their 1hr glucose is measured at 130-140 mg/dL, pending on the institution. It is generally accepted that a value >200 mg/dL is diagnostic without moving on to the second step.

The three hour test is based on a 100g glucose load. The cutoffs vary by time point. Two elevated values are needed to diagnose GDM; however, there is increased risk for the patient even with just one elevated value on three hour testing. The classic Carpenter-Coustan criteria as well as the NDDG criteria are shown here from PB 190:

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ACOG PB 190: The Carpenter-Coustan criteria are the most commonly used in the USA.

There is also single-step testing proposed by the International Association for the Study of Diabetes in Pregnancy, that uses a 75g, two-hour glucose tolerance test. Any one elevated value (fasting > 92, 1 hour > 180, or 2 hour > 153) is diagnostic of GDM, and no second screen is needed. The ADA has endorsed these criteria recently but also admits that there is not clear-cut evidence to support one screening strategy over another. ACOG endorses the two-step screening at this time.

Much of the research regarding treatment of GDM that we review in the podcast is well-reviewed in PB 190, so we won’t rehash it here. If non-pharmacologic treatments fail (monitored fasting and postprandial blood glucose levels are consistently elevated), an oral agent or insulin is required, with insulin being the gold-standard. How do you initiate insulin? See our guide below!

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And remember — postpartum patients with GDM need a 2 hour, 75 gram glucose tolerance test between 4 and 12 weeks postpartum to rule out type 2 diabetes. A fasting > 125 or a 2 hour > 200 is diagnostic. A fasting between 100-125 or a 2 hour between 140-199 demonstrates impaired glucose tolerance. And even with normal values, anyone with GDM has a 15-70% chance of developing T2DM later in life, so it’s an important part of the pregnancy history to correspond back to the patient’s PCP.