Question

A 29-year-old G4P2 Hispanic woman, with a history of gestational diabetes mellitus (GDM), presents to her OB/GYN office for a routine prenatal visit at 24 weeks’ gestation. Her physical examination is unremarkable, and her fetal well-being is reassuring. Because of her previous history of GDM, she is at high risk of developing GDM during this pregnancy and the doctor recommends a glucose challenge test, which is the most common method of screening for GDM. Test results reveal that her 1-hour glucose loading test (GLT) is 179 mg/dL (normal value <140 mg/dL). Because her GLT value is high, she then undergoes a 3-hour glucose tolerance test (GTT), which is used for a definitive diagnosis of GDM. The patient is positive for GDM when all of her plasma glucose values are elevated. Treatment recommenda- tions include beginning a diabetic diet, participating in moderate exercise sessions three times a week, daily home glucose monitoring, and weekly antepartum visits to monitor glycemic control. The doctor explained to the mother that GDM poses little risk to her at this time; however, it is associated with an increase in infant birth trauma and perinatal morbidity and mortality with the risk to her fetus directly related to its size. The goal of antepartum treatment of GDM is to prevent fetal macrosomia, which is defined as an estimated fetal weight of ⩾ 4500 grams, and its resultant complications by maintaining desirable maternal blood glucose levels throughout gestation. It was explained that if diet alone did not maintain blood glucose at desirable levels, then hypoglycemic therapy with insulin injections given several times a day may be required.

1. Why was this patient considered to be at high risk for GDM and tested at 24 weeks’ gestation?

Answer 1

Ans:

As the patient had a previous history of Gestational Diabetes Mellitus (GDM), she is at high risk of developing GDM during this pregnancy also and her glucose challenge test screening for GDM reveals that her 1-hour glucose loading test (GLT) is 179 mg/dL (normal value <140 mg/dL) . To confirm definitive diagnosis for GDM, then she undergoes a 3-hour glucose tolerance test (GTT), and the patient is test positive for GDM again. Moreover her plasma glucose values are elevated.
The patient is considered to be at high risk because GDM is generally a form of mild hyperglycaemia that reflects inadequate β-cell compensation for the body’s insulin needs. The acquired insulin resistance of pregnancy could create insulin demands that exceed β-cell capacity to supply insulin for the limited time frame of pregnancy. β-cell function is not just deficient during pregnancy in women with GDM; it deteriorates over time, and carries a small but potentially important risk of adverse perinatal outcomes and a longer-term risk of obesity and glucose intolerance in offspring. Mothers with GDM have an excess of hypertensive disorders during pregnancy and a high risk of diabetes mellitus thereafter. And the test is usually conducted on the 24-28 week of gestation because insulin resistance increases during the second trimester and glucose levels rise in women who do not have the ability to produce enough insulin to adopt this resistance. So testing too early and too late i.e; in third trimester limits the time in which metabolic interventions can take place.