Diabetes in Pregnancy Nursing CE Course

insulin production, and metabolic homeostasis. Glucose is the primary form of energy for the developing fetus and is transported across the placenta through carrier-mediated diffusion. Because of this process, the glucose level in the fetus is directly related to the glucose level in the pregnant individual. As the first trimester ends, the fetus starts secreting insulin around the 10th week of gestation. Therefore, as maternal blood glucose increases, the blood glucose level in the fetus increases, and the amount of insulin secreted by the fetus increases (Lowdermilk et al., 2016).

GDM occurs when there is any degree of glucose intolerance with an onset during pregnancy caused by pancreatic β-cell dysfunction and the release of hormones from the placenta. Lactogen is the primary hormone released by the placenta that contributes to glucose intolerance; however, growth hormone, prolactin, corticotropin-releasing hormone, and progesterone are all contributory (Quintanilla Rodriquez & Mahdy, 2022).

Pregestational Diabetes

Incidence

Pregestational diabetes is only present in 1% to 2% of all pregnancies in the US and 10% of pregnancies complicated by DM, with NIDDM being more common than IDDM. From 2000 to 2010, the percentage of individuals diagnosed with either IDDM or NIDDM before pregnancy increased by 37%. Even if the individual is not insulin dependent before pregnancy, many individuals with pregestational DM become insulin dependent during pregnancy due to the metabolic changes that occur (Centers for Disease Control and Prevention [CDC], 2018; Lowdermilk et al., 2016).

Maternal Risk and Complications During Pregnancy

Pregnant individuals with diabetes are at an increased risk of hypertension, preeclampsia, preterm birth, and maternal mortality. The likelihood of experiencing diabetes-related complications during pregnancy highly depends on the time since diagnosis and how well the patient managed their blood glucose levels before pregnancy. Individuals with DM-induced nephropathy, hypertension, or poor glycemic control before pregnancy are more likely to develop preeclampsia. Polyhydramnios (increased amniotic fluid) can occur in pregnant individuals with DM. Although usually mild, the increased fluid level may cause discomfort, premature contractions and rupture of membranes, and preterm birth in severe cases. Infections are also more common in individuals with DM that are pregnant. Vaginal infections, particularly vaginitis, and urinary tract infections (UTIs), are more prevalent in these individuals. Active infection is a concern for these individuals since it can lead to diabetic ketoacidosis (DKA). DKA occurs due to the accumulation of ketones in the blood due to hyperglycemia and can lead to metabolic acidosis, a medical emergency requiring hospitalization. Symptoms of DKA include decreased alertness, dry mouth, polydipsia, polyuria, headache, muscle stiffness, nausea or vomiting, and fruity-smelling breath. Unlike non-pregnant individuals with DM, who typically experience DKA when blood glucose levels exceed 350 mg/dL, a blood glucose level slightly above 200 mg/dL can lead to DKA in pregnant individuals with DM. In the past, when DKA occurred, the rate of intrauterine fetal demise (IUFD) was 35%; now, due to medical advances, the rate of IUFD has decreased to 10% (Durnwald, 2022b; Lowdermilk et al., 2016).

Pregnancy exacerbates diabetes-related complications, particularly retinopathy and nephropathy. Poorly controlled pregestational DM can lead to severe organ damage that may become life-threatening. Retinopathy can progress during pregnancy, especially if hypertension or poor glycemic control continues during pregnancy. Individuals at risk for retinopathy should obtain a baseline eye examination during the first trimester and be closely monitored throughout the pregnancy. Nephropathy, microalbuminuria greater than 300 mg/24 hours with or without impaired renal function, is also present in 2% to 5% of pregnancies complicated by pregestational DM. End-stage renal disease can occur in individuals with severe proteinuria during pregnancy (>3 g per 24 hours) or creatinine levels above 1.5 mg/dL. Aggressive management with antihypertensives can lead to better outcomes. Pregnant individuals with pregestational DM are 10 times more likely to develop an acute kidney injury (AKI) than pregnant individuals without pregestational DM (1.1% versus 0.1%). Individuals with a pregnancy-related AKI have a mortality rate of 2.6%, versus just 0.01% for pregnant individuals without AKI (The American College of Obstetricians and Gynecologists [ACOG], 2018b; Shah et al., 2019; Sugrue & Zera, 2018).

Interventions

Antepartum

Diet. Individuals with DM undergo nutrition counseling with a diabetic educator or dietician at their initial diagnosis. Due to the changes in the metabolic process that pregnancy causes, the individual must be further educated on how to incorporate necessary changes into their diet for glycemic control and the increased caloric demands of the pregnancy. Weight gain is expected and considered normal if it aligns with the acceptable amount for gestational age. The goals of dietary changes include weight changes consistent with a normal pregnancy, prevention of ketoacidosis, and stabilization of blood glucose levels (Lowdermilk et al., 2016).

Dietary recommendations are based on the pregnant individual's body mass index (BMI), pre-pregnancy weight, and the trimester of the pregnancy. For individuals with a BMI of 22-27, the recommended intake is 35 kcal/kg of ideal body weight daily. For individuals with a BMI greater than 30, the recommended intake is 25 kcal/kg of their actual body weight per day. This equates to approximately 2200 calories per day during the first trimester and 2500 calories per day in the second and third trimesters. This total caloric intake should be spread throughout the day as three meals and one evening snack or three smaller meals and two to three snacks throughout the day. Meals should not be skipped, and the individual must be instructed to eat at least every 4 hours to prevent a hypoglycemic episode or blood glucose fluctuations. The evening snack should include at least 25 grams of complex carbohydrates with protein or fat to prevent hypoglycemia or starvation ketosis from occurring during the night. The ideal diabetic diet should be composed of carbohydrates (55%), protein (20%), and fat (25%, with less than 10% from saturated fats). Complex carbohydrates high in fiber are recommended over simple carbohydrates due to their effects on regulating the individual's blood glucose level (Lowdermilk et al. 2016). Education for pregnant individuals with pregestational DM includes:  

• follow the diet plan
• include daily food requirements recommended for all pregnant individuals
• divide daily food intake throughout the day; never skip a meal or snack
• eat a substantial bedtime snack to prevent a severe drop in blood glucose overnight
• take daily prenatal vitamins, including iron, as prescribed
• avoid foods high in refined sugar
• avoid alcohol, nicotine, and caffeine
• avoid the use of artificial sweeteners (Lowdermilk et al., 2016)

Exercise. Regular exercise is recommended for individuals with DM; however, exercise requirements and recommendations for individuals that are pregnant with DM are limited. Exercise recommendations should be personalized and based on the patient's clinical presentation. Regular aerobic exercise may be contraindicated during pregnancy in individuals with pregestational DM and comorbidities, including severe hypertension, advanced retinopathy, or advanced peripheral neuropathy. Exercise is also contraindicated in individuals with positive urine ketones or blood glucose readings greater than 250 mg/dL due to the risk of exercise worsening these conditions. When exercise is recommended, it should be limited to 30 minutes of aerobic exercise with resistance training most days of the week. Other activities may include a non-weight-bearing workout on a stationary bike. The best time to exercise is when blood glucose levels are rising after a meal. Blood glucose levels should be monitored closely for at least 2 hours following exercise due to the risk of developing delayed exercise-induced hypoglycemia (ACOG, 2020a; Lowdermilk et al., 2016).

Blood glucose monitoring. The ACOG recommends frequent blood glucose monitoring during pregnancy, including before and after meals (Durnwald, 2022b). The ACOG and the ADA recommend the following goals for individuals with pregestational DM:

• fasting glucose less than 95 mg/dL
• preprandial (before a meal) glucose less than 100 mg/dL
• 1-hour postprandial (after a meal) glucose less than 140 mg/dL
• 2-hour postprandial glucose less than 120 mg/dL
• mean capillary glucose of 100 mg/dL
• overnight glucose levels should be above 60 mg/dL (ADA, 2021; Durnwald, 2022b)

Another way to monitor blood glucose levels is continuous glucose monitoring (CGM). This way of monitoring blood glucose levels is especially popular with those individuals with IDDM (Durnwald, 2022b). The ACOG and ADA recommend the following blood glucose goals when using CGM for patients with IDDM:

• target range of 63 mg/dL to 140 mg/dL
• time-in-range above 70% (equates to greater than 16 hours and 48 minutes)
• time-above-range less than 25% (equates to less than 6 hours)
• time-below-range less than 4% (equates to less than 1 hour) with less than 1% of the time with a blood glucose reading less than 54 mg/dL (equates to less than 14 minutes; ADA, 2021; Durnwald, 2022b)

There is a lack of research and evidence on CGM and targets for pregnant individuals with NIDDM. The individual's hemoglobin A1C (HbA1c) measures average blood glucose control over the previous 2- to 3-month period. Individuals with DM that become pregnant should have their HbA1c checked at least every trimester or more frequently if indicated. The target result of the HbA1c is 6%, indicating an average blood glucose of 120 mg/dL. A result of less than 6% indicates that the patient has experienced frequent episodes of hypoglycemia. As the pregnancy progresses, the target HbA1c may be increased to 7%. An elevated HbA1c at conception and during the first trimester has been shown to increase the risk of congenital disabilities (Durnwald, 2022b).

Medication Management. As discussed above, insulin requirements decrease during the first trimester. In subsequent trimesters the need for insulin increases, especially during the last trimester. The need for more insulin is caused by the placental hormones needed for the fetus' growth. These placental hormones block the action of insulin. Individuals with NIDDM managing their diabetes with diet and oral medications alone before pregnancy often need to transition to utilizing insulin for blood glucose control during pregnancy. Individuals with IDDM before pregnancy may need to administer insulin up to five times daily; those with an insulin pump will continue to utilize the pump for blood glucose control. As the pregnancy progresses, these individuals will require more insulin due to the insulin resistance that occurs during the last trimester. During pregnancy, insulin should be injected into the abdomen instead of other common injection sites on the extremities. This preference is due to the increased insulin absorption when using this site during pregnancy (Durnwald, 2022b).  

In individuals with IDDM, pregnancy will affect the amount of insulin required. Basal insulin delivered as intermediate-acting (NPH [Humulin N] or Humulin L) or long-acting insulin (such as glargine [Lantus] or detemir [Levemir]) suppresses hepatic gluconeogenesis in the fasting state and is necessary for individuals with IDDM. Bolus dosing of short-acting insulin, such as lispro (Humalog) and aspart (Novolog), is usually required with meals to mimic postprandial insulin secretion. The insulin resistance that occurs during pregnancy decreases the effectiveness of oral diabetic agents. Various categories of insulin and their onset, peak, and duration of action are listed in Table 1 (Durnwald, 2022b; Sugrue & Zera, 2018).

Table 1

Common Insulin Preparations 

Type of Insulin	Examples	Onset of Action	Peak of Action	Duration of Action	Administration
Rapid-acting	Lispro (Humalog)	15 min	30-90 min	4-5 hr	It can be mixed in a syringe with other insulins.
	Aspart (Novolog)	15 min	1-3 hr	3-5 hr
Short-acting	Humulin R	30 min	2-4 hr	5-7 hr	It can be mixed in the syringe with other insulins.
	Novolin R	30 min	2.5-5 hr	6-8 hr
Intermediate-acting	NPH (Humulin N)	1-2 hr	6-12 hr	18-24 hr	It can be mixed in the syringe with other insulins.
	Novolin N	1.5 hr	4-20 hr	24 hr
	Humulin L	1-3 hr	6-12 hr	18-24 hr
	Novolin L	2.5 hr	7-15 hr	22 hr
Long-acting	Detemir (Levemir)	1 hr	None	8-24 hr	It cannot be mixed in the syringe with any other insulins.
	Glargine (Lantus)	1 hr	None	24 hr

(Lowdermilk et al., 2016; Woods, 2023)

 

Fetal Surveillance. A baseline ultrasound is completed early in pregnancy to determine gestational age and fetal size. Follow-up ultrasounds are conducted as often as every 3 to 4 weeks to monitor fetal growth for signs of microsomia or macrosomia, detect hydramnios, or any other congenital abnormalities. Due to the increased risk of neural tube defects in the fetus of an individual with pregestational DM, a serum alpha-fetoprotein measurement is completed between 16 and 18 weeks of gestation, and a detailed ultrasound is completed between weeks 18 and 20. Late in the first trimester, fetal nuchal translucency (NG) measurement and maternal screening can lead to the early detection of cardiac abnormalities. A fetal echocardiogram may also be performed between weeks 20 and 22. This test is beneficial in individuals that did not control their blood glucose levels during the first trimester, indicated by an HbA1c greater than 6% at the first prenatal check-up. Individuals with pregestational DM that also have vascular disease may have doppler studies performed on the umbilical artery to screen for placental compromise (Lowdermilk et al., 2016).

More fetal monitoring occurs during the third trimester, when the risk of fetal compromise is the highest. In addition to testing, the pregnant individual should be taught how to self-monitor fetal movement by performing kick counts starting at 28 weeks. In week 32, nonstress tests (NSTs) should be conducted twice weekly. NSTs are the primary method used to evaluate the well-being of the fetus. Individuals with vascular disease or poor glucose control often start NSTs in week 28. If the NST is non-reactive, a biophysical profile or contraction stress test should be performed. The ACOG recommends that individuals with controlled pregestational DM deliver between 39 0/7 and 6/7 weeks. Individuals with poorly controlled pregestational DM should deliver between 36 0/7 weeks and 38 6/7 weeks (ACOG, 2018b; Lowdermilk et al., 2016).

Intrapartum 

Glycemic control in patients with pregestational DM remains essential even during labor. Hyperglycemia during labor can lead to fetal hypoxemia and neonatal hypoglycemia. Many factors can affect blood glucose levels during labor, including increased metabolic demands, food restriction, and infusion of intravenous (IV) fluids containing dextrose. The ACOG recommends an intrapartum glucose target of 70 to 110 mg/dL, and the Endocrine Society Clinical Practice Guidelines recommend a target of 72 to 126 mg/dL. In individuals with pre-existing DM, the intrapartum interventions change based on which stage of labor the individual is currently in and whether they have IDDM or NIDDM. During latent labor, if the individual can still eat and drink unrestricted, blood glucose monitoring follows the individual's antepartum monitoring frequency. Individuals with IDDM will continue to need basal, preprandial, and correctional insulin doses. If oral intake is reduced from normal, a reduction of 20% to 30% of the patient's home insulin dose may be necessary to prevent hypoglycemia. Once oral intake is restricted in an individual with NIDDM, blood glucose is monitored at least every 4 hours, with insulin administered when indicated based on a sliding scale. If the individual is still taking oral antihyperglycemic medications, they are discontinued once the individual is admitted to the hospital (Powe, 2022).  

Once active labor begins, blood glucose levels are monitored more closely due to the increased stress on the body and the complications that can occur if blood glucose levels are not controlled during this stage. Once an individual with IDDM begins active labor or food is restricted, even if still in the latent phase, blood glucose monitoring increases to hourly, and dextrose-containing IV fluids and a continuous insulin infusion are indicated. These infusions are titrated based on blood glucose levels following facility protocol. The continuous insulin infusion is started first; dextrose-containing IV fluids are initiated once the blood glucose level drops below 160 mg/dL. Any further increase in blood glucose should be managed by titrating the insulin dose (Dude et al., 2018; Powe, 2022).

Once an individual with NIDDM enters the active phase of labor, blood glucose checks occur every 2 to 4 hours. If the initial check is above 200 mg/dL, a continuous IV insulin infusion is initiated following a standard protocol. If the initial reading is less than 200 mg/dL, subcutaneous insulin is administered following a sliding scale. A continuous IV insulin infusion is initiated if the patient's blood glucose readings are consistently above 125 mg/dL over multiple checks. Once the IV insulin infusion is initiated, the frequency of blood glucose checks increases to every 1 to 2 hours. Dextrose-containing IV fluids are started once the patient's blood glucose level drops below 160 mg/dL if on IV insulin or below 125 mg/dL if on subcutaneous insulin. Like above, any future increases in blood glucose are managed by titrating the insulin dose. In either scenario, once a continuous insulin infusion begins, another IV line should be initiated to administer oxytocin (Pitocin), antibiotics, magnesium sulfate, or analgesics. It is also recommended that Lactated Ringers be given as maintenance fluid once an insulin infusion begins (Dude et al., 2018; Powe, 2022).

Postpartum 

During the postpartum period, there is an increased risk of the individual experiencing hypoglycemia due to the rapid drop in diabetogenic placental hormones. In the immediate recovery period, individuals with IDDM should have their basal IV insulin dose decreased by 50%. Lactated ringers (if being used as maintenance fluid) and dextrose infusions should continue. For individuals with NIDDM, the IV insulin dose should be reduced by 50% or discontinued if blood glucose results are within normal limits. For all individuals with pregestational DM, blood glucose checks should be completed hourly during the recovery period. The individual should also be encouraged to breastfeed due to the positive effects on blood glucose control (Dude et al., 2018; Powe, 2022).  

 

Gestational Diabetes Mellitus

Incidence

GDM occurs in approximately 7% of all pregnancies or 200,000 cases annually in the US. GDM affects about 14% of pregnant individuals worldwide, equating to over 18 million pregnancies annually. The rates of GDM have been increasing; between 2000 and 2010, the number of individuals diagnosed with GDM increased by 56%. The rate of GDM continued to grow until 2017, when rates stabilized. This increase has been attributed to the rise in overweight and obese individuals (CDC, 2018; Lowdermilk et al., 2016; Zhou et al., 2022).

Risk Factors 

GDM is more likely to occur in Hispanic, African American, Native American, Asian, and Pacific Islander individuals. Once an individual is diagnosed with GDM, they are at an increased risk of developing GDM in future pregnancies. Other non-modifiable risk factors include a family history of a first-degree relative with NIDDM, polycystic ovarian syndrome (PCOS), a past pregnancy that resulted in unexplained IUFD or fetal macrosomia, and maternal age above 25. Modifiable risk factors include obesity (BMI greater than 25), hypertension, glycosuria (glucose in the urine), low high-density lipoprotein (HDL), triglycerides greater than 250, and HbA1c greater than 5.7% (Lowdermilk et al., 2016; Quintanilla Rodriguez & Mahdy, 2022).

Screening

Different organizations have recommendations that address the timing of screening and screening procedures for GDM. For the average patient, GDM screening occurs between 24 and 28 weeks, when glucose intolerance begins. The ADA and ACOG recommend early screening before 24 weeks for patients with an increased risk of NIDDM, including those with GDM in a previous pregnancy, HbA1c greater than 5.7%, a first-degree relative with NIDDM, history of cardiovascular disease, hyperlipidemia, physical inactivity, and controlled or uncontrolled hypertension. The US Preventive Services Task Force (USPSTF) does not support early screening of asymptomatic individuals, even if risk factors for NIDDM are present (AGOG, 2018a; Durnwald, 2022a).

Two oral glucose tolerance tests (OGTTs) are used to screen patients for GDM, the 1-step OGTT and the 2-step OGTT. The ACOG recommends the 2-step approach to GDM screening, while the ADA supports using either the 1-step or 2-step OGTTs. The 1-step approach simplifies the screening process since only one diagnostic test is used. For the 1-step OGTT, the individual must fast (nothing to eat or drink except for sips of water) for 8 to 14 hours before arriving at the lab. Once a pretest (fasting) blood sample is obtained, a solution containing 75 g of glucose is administered orally (Durnwald, 2022a). Once the glucose solution is administered, a blood sample is obtained every 60 minutes for 2 hours. Abnormal results are as follows:

• fasting glucose ≥ 126 mg/dL
• 1-hour glucose ≥ 180 mg/dL
• 2-hour glucose ≥ 200 mg/dL

The 2-step OGTT is the most widely used test for identifying individuals with GDM in the US. During the first step, a solution containing 50 g of glucose is administered orally. The patient does not need to be fasting, so this test can be completed at any time of day. A blood sample is obtained one hour after administration of the glucose solution. Different thresholds are used to determine if the test is positive based on provider or facility guidelines; however, most institutions consider the test positive if the blood glucose level after 1 hour is greater than 130 mg/dL or 140 mg/dL. If the first step is positive, the second step is completed on a different day. In preparation for the second step, or 3-hour OGTT, the individual must fast for at least 8 hours before testing. A blood sample is obtained upon arrival at the lab to determine the fasting blood glucose level. The individual is then given a solution containing 100 g of glucose to drink. Blood samples are then taken at 1, 2, and 3 hours following administration of the glucose solution. A 3-hr OGTT is considered positive if the individual's blood glucose results at two different points are above the threshold. Two guidelines are commonly followed in the US to determine the threshold of blood glucose levels. See Table 2 below. If the patient has two positive results during the 3-hr OGTT, they are considered to have GDM (Coustan et al., 2021; Durnwald, 2022a;).

Table 2

3-Hour OGTT Diagnostic Guidelines

	Carpenter and Coustan (plasma or serum)	National Diabetes Data Group (plasma)
Fasting	95 mg/dL	105 mg/dL
One hour	180 mg/dL	190 mg/dL
Two hours	155 mg/dL	165 mg/dL
Three hours	140 mg/dL	145 mg/dL

                                                                                           (Coustan et al., 2021; Durnwald, 2022a)

Interventions

Antepartum

Once a diagnosis of GDM is confirmed, treatment and lifestyle changes are implemented as quickly as possible to mitigate potential effects on the individual and the developing fetus. Unfortunately, this quick turnaround does not allow much time for the pregnant individual to come to terms with their diagnosis (Lowdermilk et al., 2016).

 

Diet. Dietary modifications are the initial treatment for GDM. Once GDM is diagnosed, the individual is started on a diabetic diet with a recommended daily intake based on their pregestational weight. The recommended daily intake for individuals with a healthy pregestational weight is 30 kcal/kg/day. The recommended intake for individuals with pre-existing obesity before pregnancy is 25 kcal/kg/day or 1500 to 2000 kcal/day. Carbohydrate intake is also limited to 50% of all caloric intake. Individuals with a new diagnosis of GDM should also be referred to a dietician specializing in diabetic nutrition (ACOG, 2018a; Lowdermilk et al., 2016).

Exercise. A moderate-intensity exercise regimen of 30 minutes per day for at least 5 days a week for a minimum of 150 minutes per week is recommended for individuals diagnosed with GDM. Adherence to an exercise routine is even more critical in those individuals that are overweight or obese to provide better blood sugar control and promote weight loss (ACOG, 2018a; Lowdermilk et al., 2016).

Glucose Monitoring. Glucose monitoring recommendations for individuals diagnosed with GDM are individualized, but blood glucose checks should occur at least daily. Monitoring typically occurs upon waking in the morning (or whatever time of day the individual first awakens), 1 to 2 hours after eating breakfast, before and after eating lunch, before dinner, and at bedtime. Individuals with GDM monitor their blood glucose at home and review their trends at their prenatal check-up appointments. Pharmacologic treatment should be initiated if non-pharmacologic interventions are not effectively controlling blood glucose levels (Lowdermilk et al., 2016).

Treatment. First-line treatment for individuals diagnosed with GDM includes dietary modifications and exercise alone. Despite compliance with non-pharmacologic interventions, approximately 25% of individuals diagnosed with GDM will require insulin to regulate blood glucose levels. Within the last several years, oral hypoglycemics have been used before initiating insulin treatment. Oral hypoglycemics can be beneficial in individuals unwilling or cognitively incapable of self-administering insulin injections. Glyburide (Diabeta) is the oral hypoglycemic most used for patients with GDM. Glyburide (Diabeta) is a sulfonylurea that works by inducing the pancreas to secrete more insulin. Side effects include hypoglycemia, weight gain, and the development of dermatitis. This drug is a desirable choice for pregnant individuals as only a small amount of the drug can cross the placenta. Metformin (Glucophage) is another oral hypoglycemic commonly used to treat GDM. Metformin (Glucophage) is a biguanide, a group of medications that work by lowering glucose production in the liver and improving the way the body utilizes insulin. Side effects include nausea and diarrhea. Metformin can cross the placenta but is not teratogenic. Glyburide (Diabeta) is typically more effective than metformin (Glucophage) at controlling blood glucose levels in individuals with GDM (Lowdermilk et al., 2016; Woods, 2023).

Insulin should be initiated when the individuals fasting glucose readings are consistently above 95 mg/dL, 1-hour post-meal readings are above 140 mg/dL, and 2-hour post-meal readings are above 120 mg/dL. Different categories of insulin and their onset, peak, and duration of action are listed in Table 1 (Lowdermilk et al., 2016).

Fetal Surveillance. When GDM is controlled with dietary modifications and exercise alone, there is minimal risk of IUFD. Due to this low risk, fetal monitoring is not increased in these individuals unless there is a comorbidity, such as hypertension, a history of IUFD, or if fetal macrosomia is suspected. Individuals with GDM complicated by comorbidities or requiring pharmacological intervention to control blood glucose should have twice-weekly non-stress tests (NSTs) starting at week 32. Delivery for these individuals should occur between 36 0/7 weeks and 38 6/7 weeks based on NST results. Individuals with uncomplicated GDM begin NSTs at week 40. These individuals may continue their pregnancy into the 40th week and the spontaneous onset of labor. Despite this lack of routine monitoring, the size of the fetus should be assessed as the pregnancy approaches the 40-week mark since the risk of macrosomia increases the longer the pregnancy progresses. The pregnancy should not go beyond 40 6/7 weeks gestation (ACOG, 2018a; Lowdermilk et al., 2016).

Intrapartum

The patient's blood glucose levels should be checked hourly during labor. The ideal range is 80 to 110 mg/dL since this level decreases the risk of neonatal hypoglycemia. To maintain this level, the individual may need rapid-acting insulin continuously infused intravenously during labor. Maintaining this range may also be achieved by eliminating the infusion of IV fluids that contain dextrose. Although a diagnosis of GDM does not mean that the individual must undergo cesarean delivery, this may be necessary if the individual develops preeclampsia or if fetal macrosomia is present (Lowdermilk et al., 2016).

Postpartum 

It is essential to monitor individuals with GDM closely as insulin requirements decrease rapidly in the first few postpartum days, with requirements returning to baseline within 48 hours for most individuals. Often GDM resolves following delivery, and individuals regain the ability to regulate blood glucose levels with the same efficiency as they were able to pregestational; however, approximately 33% of individuals with GDM are still found to have DM when screened at their postpartum appointment. The ACOG recommends screening individuals with GDM between 6 and 12 weeks postpartum using either a 75 g 2-hour OGTT or a fasting glucose level (Durnwald, 2022b; Lowdermilk et al., 2016).

 

Fetal Risk 

Since GDM does not occur until after the first trimester, it does not usually lead to congenital disabilities, as the critical period of organ development occurs during the first trimester (Lowdermilk et al., 2016).  

Maternal Risk 

GDM is a risk factor for developing NIDDM, and individuals with GDM have a 35% to 60% increased risk of being diagnosed with NIDDM 10 to 20 years following pregnancy. One population-based study found that 18.9% of individuals who had GDM developed NIDDM within 9 years of the affected pregnancy. Due to this increased risk, individuals diagnosed with GDM during pregnancy should be screened for NIDDM every 3 years (Lowdermilk et al., 2016; Quintanilla Rodriguez, 2022). To prevent NIDDM from occurring later in life, the patient can:

• maintain a healthy BMI since obesity increases the risk of developing NIDDM
• increase physical activity to at least 30 minutes per day, 5 days per week
• make healthy food choices and limit fat intake (CDC, 2018)

A history of GDM also puts the individual at an increased risk of developing metabolic syndrome and cardiovascular disease. Metabolic syndrome is characterized by obesity, hypertension, insulin resistance, and dyslipidemia. There has been a link between GDM and mortality following pregnancy due to cardiovascular changes and complications such as hypertension, obesity, and dyslipidemia. GDM also increases an individual's lifetime risk of undergoing noninvasive diagnostic cardiac procedures, cardiovascular events, and hospitalizations due to cardiovascular complications (Sheiner, 2020).  

GDM during pregnancy can also increase an individual's risk of developing malignancies later in life. There is a correlation between GDM and ovarian, endometrial, and breast cancer. Individuals with GDM are also at an increased risk of developing pancreatic cancer. GDM can also have significant effects on the eyes leading to ophthalmic disease and long-term ophthalmic morbidity. Individuals with GDM are more likely to develop glaucoma, diabetic retinopathy, or retinal detachment than those without GDM. Renal disease can also occur because of GDM. The most common disorders seen later in life in individuals that have had GDM include hypertensive renal disease with and without renal failure, chronic renal failure, and end-stage renal disease (Sheiner, 2020).

 

Overall Implications

Infant Assessment 

Infants born from diabetic individuals may have specific outward characteristics. These infants are often oversized for their gestational age, very plump, and have full faces. These infants are also frequently born liberally covered with vernix. The placenta and umbilical cord are also often larger than average. Due to hyperbilirubinemia, the infant may appear jaundiced (Hockenberry et al., 2019).

Risks and Complications

Poor glycemic control during the late stages of pregnancy can lead to fetal macrosomia. Macrosomia is defined as an infant weighing 4,000 g (8 lb 13 oz) to 4,500 g (9 lb 15 oz) or above the 90th percentile in weight for gestational age. Fetal macrosomia occurs in 40% of pregestational DM pregnancies and 50% of GDM pregnancies. As the fetus is exposed to increased glucose via the placenta, the excess is stored as body fat. Fetal macrosomia can also affect the delivery of the fetus. Due to increased size, the fetus may be unable to enter or progress down the birth canal resulting in a cesarean section. The rate of cesarean section doubles when the fetus weighs more than 4,500 grams. Those fetuses that can enter the birth canal may need to be delivered using forceps or a vacuum extractor. The provider may also need to perform an episiotomy to prevent perineal tearing because of increased fetal size. After delivery, the infant may display signs of injury from the birthing process due to its increased size. The size increase is most likely to affect the shoulders, trunk, and chest size. Due to this increase in size, shoulder dystocia occurs more frequently in these infants than in other infants with fetal macrosomia attributed to another cause. It is the most severe complication associated with fetal macrosomia. When birth weight is over 4,500 g, shoulder dystocia's incidence increases from 19.9% to 50%. Other injuries include brachial plexus injury and palsy, fractured clavicle, or phrenic nerve palsy. The nurse must assist and monitor the infant for these injuries. Although fetal macrosomia is more common, individuals with IDDM and pre-existing vascular complications or hypertension may have intrauterine growth restriction leading to fetal microsomia. This is defined as a fetus with a weight less than the 10th percentile for gestational age (ACOG, 2020b; Durnwald, 2022b; Hockenberry et al., 2019; Lowdermilk et al., 2016).

After delivery, the infant is at risk of developing certain conditions due to exposure to increased glucose while in utero. The infant may experience hypoglycemia, hyperbilirubinemia, hypomagnesemia, pulmonary complications (e.g., respiratory distress syndrome), polycythemia (excessive red blood cells), hypocalcemia, and cardiac abnormalities. These complications are more prevalent when the pregnant individual's blood glucose levels have been unmanaged and elevated throughout the pregnancy. Pulmonary complications are especially concerning and require monitoring in the special care nursery. Pulmonary complications are common in infants born to individuals with DM since lung development is delayed in these infants (Durnwald, 2022b).

The infant born to an individual with DM is also more at risk of congenital abnormalities. These include central nervous system defects such as anencephaly and spina bifida, which occur in these infants at rates 16% higher than infants born to nondiabetic individuals. Cardiac defects such as ventriculoseptal defects occur in 30% of infants born to an individual with DM. Being born to an individual with DM can increase the infant's risk of developing a metabolic disorder later in life. This includes obesity, hypertension, dyslipidemia, and glucose intolerance. Studies have found a strong correlation between exposure to increased glucose in utero and increased childhood BMI. The rate of obesity in the children of individuals with uncontrolled GDM is 7.8%. That number decreases to 4.9% when GDM is controlled; however, the rate of obesity in children of individuals with no history of GDM is 1.8%. Children born to individuals with DM treated with medication also have an increased risk of ophthalmic morbidity (Hockenberry et al., 2019; Sheiner, 2020). 

 

Infant Monitoring 

Infants born to individuals with DM should be monitored closely. Serum levels of calcium and bilirubin should be monitored. Hypoglycemia can occur shortly after birth due to the hypertrophy and hyperplasia of the pancreatic islet cells in infants born to individuals with DM; therefore, serum blood glucose levels should be monitored closely. It is recommended that intervention be initiated for an infant with a blood glucose level less than 45 mg/dL. First-line treatment is to allow the infant to feed by either the bottle or breast. If blood glucose levels have not increased or signs of hypoglycemia begin to develop after two feeding attempts, IV glucose should be administered. In infants under 4 hours old, IV glucose is indicated for a blood glucose level at or below 25 mg/dL. In infants older than 4 hours, IV glucose should be administered when blood glucose levels drop below 35 mg/dL. In infants with hyperinsulinemic hypoglycemia, blood glucose levels should be maintained at 50 mg/dL or above (Hockenberry et al., 2019).

Nursing care for these infants includes completing a detailed assessment and checking for congenital disabilities, injuries, or cardiac or respiratory failure signs. The nurse should assist with thermoregulation and the introduction of carbohydrate feedings. It is also the nurse's responsibility to check the infant's blood glucose level frequently and monitor for signs of hypoglycemia. If IV glucose is indicated, the nurse must monitor the infant for adverse reactions to the treatment and the site for signs of infiltration or phlebitis (Hockenberry et al., 2019).

Breastfeeding 

Breastfeeding is recommended for all postpartum individuals as there are numerous benefits for both the individual and the infant. Breastfeeding is especially beneficial for individuals with DM. Individuals with DM experience improved metabolic function and increased insulin sensitivity while breastfeeding. Those individuals that rely on insulin to maintain euglycemia may be able to reduce the necessary dose while breastfeeding due to the metabolic improvements seen. One study on breastfeeding postpartum individuals with IDDM showed a 21% reduction in insulin requirements versus their pregestational dose. It is essential to monitor blood glucose levels to prevent hypoglycemia, especially at night when the infant is nursing, and the breastfeeding individual may not be eating. The breastfeeding individual with DM is at an increased risk of mastitis or a yeast infection of the breast, especially if blood glucose levels are not well controlled (Lowdermilk et al., 2016; Macdonald, 2019a, 2019b).

Studies have shown that breastfeeding for at least 3 months following delivery can be a protective factor against developing NIDDM later in life. One 30-year study showed that the longer breastfeeding is extended, the lower the risk of developing NIDDM (Macdonald, 2019a, 2019b; Much et al., 2014). A meta-analysis by Rameez and colleagues (2019) with over 200,000 participants indicated that breasting for longer than 12 months decreases the risk of developing NIDDM by 30% and hypertension by 13%. It is essential to address the individual's breastfeeding concerns while educating and preparing them to succeed. Due to metabolic changes, the individual may experience delayed lactogenesis or decreased milk production in the early postpartum period. There may also be a delay in contact with the infant due to complications during delivery, delivery via cesarean section, or health concerns in the infant. The individual should also meet with a dietician to review dietary changes that will need to be made to support the caloric needs of breastfeeding while maintaining blood glucose control (Lowdermilk et al., 2016; Macdonald, 2019a, 2019b). For additional details, please see the NursingCE course on Breastfeeding.

References

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