Overview/pathophysiology

According to the National Diabetes Data Group Classification, there are four types of diabetes (ADA, 2006). They are type 1 diabetes mellitus (DM), called insulin-dependent diabetes; type 2 DM, called insulin-resistant diabetes; diabetes dependent on other specific conditions such as infection or drug induced; and gestational diabetes mellitus (GDM). GDM is defined as carbohydrate intolerance that is first recognized during pregnancy. There is a 50% risk of GDM turning to chronic DM within 5 yr after diagnosis if no lifestyle changes are made. Both types of diabetes pose significant risks to maternal/fetal morbidity and mortality. Incidence of diabetes in pregnancy has increased because more women are delaying pregnancy until relatively late into their reproductive years. Currently the incidence is 4%-14% (B. Gilbert, 2007).

Health care setting

Primary care (outpatient obstetric clinic, high-risk perinatal clinic); or acute care (inpatient): Hospitalization is sought when starting or adjusting insulin, if an infection develops, or during third trimester when diabetes has been poorly controlled and closer maternal and fetal observation is indicated

Assessment

At the first prenatal visit all women are screened for a history of clinical risk factors when obtaining a history. Between 24-28 wk gestation, every pregnant woman should be screened for GDM by the 1-hr glucose challenge test. Screening is recommended even for patients with low risk factors (age younger than 25 yr, not a member of an ethnic group at risk for developing type 2 DM, body mass index [BMI] less than 25, no previous history of abnormal glucose tolerance, no previous history of adverse obstetric outcomes that are usually associated with GDM, and no known diabetes in a first-degree relative [mother, father, siblings]). Pregnant patients with a previous history of GDM may be screened earlier in the current pregnancy to diagnose GDM and initiate dietary changes and medications as needed to ensure better glycemic control (euglycemia) and decrease untoward consequences to the fetus.

Diagnostic tests

1-hr glucose screening:

Performed between wk 24-28 of the pregnancy or earlier, even at the initial prenatal visit. If results are negative in an earlier test, the test is repeated between 24 and 28 wk in the pregnancy if patient meets risk factors (discussed earlier). This test requires the patient to drink a 50-g glucose load, followed in 1 hr by venous plasma measurement. Traditionally a value of 140 mg/dL or greater was considered abnormal and indicated need for the 3-hr 100-g oral glucose tolerance test. There is evidence that a 130 mg/dL cut off level identifies 10% more women at risk for GDM. When a 1-hr value is 190 mg/dL or greater, a fasting glucose should be done before proceeding to the 3-hr test. If the fasting value is 95 mg/dL or greater, the patient is treated for GDM.

3-hr glucose tolerance test:

After fasting for 8-12 hr and abstaining from smoking, a fasting blood sugar (FBS) is drawn after which the patient drinks a 100-g glucose load followed by serum venous plasma measurements at 1, 2, and 3 hr. Two of the four values need to be abnormal to make the diagnosis of GDM.

Note: Screening guidelines differ for diagnosing GDM, depending on medical facility preference. American College of Obstetrics and Gynecology (ACOG) recommends the 3-hr oral glucose tolerance test (OGTT) for women who test positive with a 1-h, 50-g OGTT. If two or more blood glucose levels are elevated, the diagnosis is established for GDM.

Fasting: greater than 95 mg/dL

1-hr: greater than 180 mg/dL

2-hr: greater than 155 mg/dL

3-hr: greater than 140 mg/dL

National Institutes of Health and Clinical Excellence group recommend using a 2-h, 75-g OGTT to screen for gestational diabetes and to diagnose with the World Health Organization (WHO) criteria.

Fasting: 7.0 mmol/ L (126 mg/dL) or higher

2-hr: 7.8 mmol/L (140 mg/dL) or higher

Glycosylated hemoglobin (hemoglobin A_1C):

Reflects the average blood sugar levels for the 2- to 3-mo period before the test. Values may be increased in iron-deficient anemia and decreased in pregnancy. Levels less than 6% are desired in pregnancy. Recent studies have raised questions about the reliability of Hemoglobin A_1C results in the second and third trimesters of pregnancy; therefore, it is no longer recommended as a routine assessment of glycemic control in those trimesters.

Home glucose monitoring:

The patient at home performs glucose monitoring (obtaining whole blood from a fingerstick) at given intervals prescribed by the health care provider. Taking into account the risk of hypoglycemia, target values during pregnancy are FBS less than 95 mg/dL and 2-hr postprandial (pp) 120 mg/dL or less. Patients with poor glucose control will have FBS well above 90-95 mg/dL and 2-hr pp well above 120 mg/dL. Careful regulation of maternal glucose levels during pregnancy leads to decreased maternal/fetal compromise and better outcomes.

Renal function studies:

Normally during pregnancy creatinine clearance is increased, but it is decreased in GDM because of deterioration in glomerular function. A 24-hr urinalysis for protein is recommended early in the pregnancy that can be used as a comparison later if renal function worsens.

Obstetric ultrasound:

May be done at 2- to 4-wk intervals to monitor fetal growth, placental function, amniotic fluid levels, and fetal position and check for presence of polyhydramnios (excess amniotic fluid). If the primary Hemoglobin A_1C is elevated, a fetal echocardiogram may be done between 20 and 22 wk gestation. Ultrasounds also assess fetal anomalies for women with pregestational diabetes.

Antepartum fetal monitoring:

Patients with GDM whose blood glucose levels are well controlled by diet are at low risk for fetal complications. Antepartum fetal heart rate testing is limited unless they have hypertension, history of prior stillbirth, or current fetal macrosomia. Any of these conditions would necessitate weekly to twice weekly testing starting at 32 wk (or sooner if necessary) to monitor fetal well-being. Ultrasound monitoring of fetal growth is recommended in the last few weeks of pregnancy because of the risk for macrosomia.

Nursing diagnosis:

Risk for unstable glucose level

related to fluctuations occurring during pregnancy

Desired Outcome: Euglycemia is maintained as evidenced by daily maternal records and prenatal testing results.

ASSESSMENT/INTERVENTIONS	RATIONALES
PRENATAL: Assess the patient’s Hemoglobin A1C and blood glucose by the method and timing prescribed by the health care provider.	Hemoglobin A1C testing is recommended for patients with pregestational DM. Hemoglobin A1C levels above 8% are associated with a higher rate of congenital anomalies. Recent studies raise questions about its reliability in second and third trimesters. Target daily glycemic controls in pregnancy by fingerstick are FBS of 95 mg/dL or less and 2-hr pp levels of 120 mg/dL or less.
Assess the patient’s urine by dipstick for glucose and ketones and review maternal monitoring charts as prescribed by the health care provider.	The renal threshold for glycosuria is lower in pregnancy. Glycosuria predisposes the patient to urinary tract infections.
Assess daily diet compliance according to the American Diabetic Association (ADA) diet prescribed by the dietitian.	GDM may be controlled by diet alone.
Explain to the patient with GDM and her family that insulin administration may be necessary as pregnancy progresses.	The body’s insulin requirements double or quadruple by the third trimester. If diet repeatedly fails to keep fasting glucose at 100 mg/dL or less, insulin therapy is recommended.
Assess the patient’s self administration of human insulin according to the regimen prescribed by the health care provider.	Many pregnant women with diabetes want to administer their own insulin dose. Professional assessment identifies whether the patient’s technique is safe or needs refinement by education.
Assess fundal height and compare to previous level and gestational week as prescribed by the health care provider.	If euglycemia is not maintained throughout pregnancy, the fetus is at risk for macrosomia or intrauterine growth restriction (IUGR).
Coordinate referrals after hospital discharge as prescribed; for example, to a perinatologist, endocrinologist, diabetic nurse, dietitian, and medical social worker (MSW).	Coordination of referrals fosters continuity of care and timely communication among many health care providers.
INTRAPARTUM: Assess and document blood glucose levels hourly by fingerstick and as prescribed after insulin administration.	Maintenance of euglycemia (75-126 mg/dL [4.0-7.0 mmol/L]) in labor reduces the risk for neonatal hypoglycemia, which is especially critical during the first hour of birth when the newborn is no longer experiencing the same glucose level as the mother.
If blood glucose rises to 126 mg/dL (7 mmol/L) or higher, begin insulin infusion by a secondary intravenous line at 2 units/hr in 0.9% normal saline as prescribed by health care provider.	Blood glucose requirements vary in labor (e.g., food intake is reduced), and oxytocin acts like insulin and drives glucose into the body cells. Normoglycemia in Intensive Care Evaluation (NICE) guidelines for labor recommend that blood glucose remain between 75 and 126 mg/dL (4.0-7.0 mmol/L) by glucometer.
POSTPARTUM: Assess fasting blood glucose level as prescribed. Encourage patient to maintain a balanced diet and have a snack available during breastfeeding bouts.	After the placenta is expelled, human placental lactogen (hPL) decreases and the insulin resistance during pregnancy resolves quickly. Insulin needs in the pregestational patient with diabetes are markedly reduced, often below prepregnant needs for 24 hr. The patient with GDM returns to nonpregnant carbohydrate metabolism. Breastfeeding uses blood glucose and increases the risk of hypoglycemia.

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