Glucose intolerance during pregnancy, GD is associated with an increase in perinatal morbidity and mortality, especially in women who are older than 25 years, overweight, obese, or hypertensive. In addition, more than one half of all pregnant patients with an abnormal GTT do not have any of the same risk factors. It is therefore recommended by the ADA that all pregnant women be screened for GD as follows: Women with presence of risk factors should be screened at the first prenatal visit, and women with no known prior diabetes should be screened at 24–28 weeks.
A diabetes risk assessment should be done at the first prenatal visit. Testing should be performed in those with risk factors using standard criteria. Testing should occur again at 24–28 weeks.
Two approaches may be followed for GD screening at 24–28 weeks:
Two-step approach:
Perform initial screening by measuring plasma or serum glucose 1 hour after a 50-g load of 140 mg/dL identifies 80% of women with GD, whereas the sensitivity is further increased to 90% by a threshold of 130 mg/dL.
Perform a diagnostic 100-g OGTT on a separate day in women who exceed the chosen threshold on 50-g screening.
One-step approach (may be preferred in clinics with high prevalence of GD): Perform a diagnostic 75-g OGTT in all women to be tested at 24–28 weeks. The 75-g OGTT should be performed in the morning after an overnight fast of at least 8 hours.
Draw a 5-mL venous blood sample (sodium fluoride) after an 8- to 14-hour fast, at least 3 days of unrestricted diet and activity, and after glucose load.
Observe standard precautions. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.
A positive result in a pregnant woman means she is at much greater risk (seven times) for having GD.
GD is any degree of glucose intolerance with onset during pregnancy or first recognized during pregnancy.
Pretest Patient Care
Explain test purpose (to evaluate abnormal carbohydrate metabolism and predict diabetes in later life) and procedure. No fasting is usually required. Obtain pertinent history of diabetes and record any signs or symptoms of diabetes.
Instruct the woman about obtaining a urine sample for glucose testing to check before drinking the glucose load. Positive urine glucose should be checked with the healthcare provider before glucose load. Those with glycosuria >250 mg/dL (>13.8 mmol/L) must have a blood glucose test before GD testing.
Give the patient the appropriate glucose beverage.
Explain to the patient that no eating, drinking, smoking, or gum chewing is allowed during the testing period. The patient should not leave the office. They may void if necessary.
After 1 hour, draw one NaF or EDTA tube (5-mL venous blood) using standard venipuncture technique.
Posttest Patient Care
Have the patient resume normal activities, eating, and drinking.
Review test results; report and record findings. Modify the nursing care plan as needed. Explain to the patient what interventions to expect for a normal outcome.
6–12 weeks after delivery, the patient should be retested and reclassified. In most cases, glucose will return to normal.
To make a diagnosis of GD, any of the following PG values must be found after the one-step approach:
FPG >92 mg/dL (>5.1 mmol/L)
1-hour >180 mg/dL (>10.0 mmol/L)
2-hour >153 mg/dL (>8.5 mmol/L)
To make a diagnosis of GD, at least two of the following PG values must be found after the two-step approach:
FPG >95 mg/dL (>5.3 mmol/L)
1-hour >180 mg/dL (>10.0 mmol/L)
2-hour >155 mg/dL (>8.6 mmol/L)
3-hour >140 mg/dL (>7.8 mmol/L)