Late Gestational Diabetes Mellitus Diagnosis in Obese Women

In the current work, we aim to perform a prospective study that will investigate the relationship between maternal obesity (BMI \>30 kg/m2) and morbid obesity (BMI \>35 kg/m2) with a late GDM diagnosis (\>32 weeks), with an emphasis on obstetric and neonatal outcomes.

Methods

Study design:

A prospective study that will evaluate the rate of diagnosis of late GDM and clinical effect of performing a repeat OGTT beyond week 32 in women with obesity (BMI \>30 kg/m2) and morbid obesity (BMI \>35 kg/m2) for whom loading sugar was normal in the second trimester. The study will be carried out in the Mother and Fetus Unit at the Galilee Medical Center in Nahariya, Israel.

Study population:

Target population: women hospitalized in the Mother and Fetus Unit for various reasons, e.g., premature labor, amniotic fluid leakage, reduced fetal movements, following a car accident, etc.

Inclusion criteria:

1. Women with normal OGTT at weeks 24-28
2. Women with BMI \>30 kg/m2

Exclusion criteria:

1. Twins
2. Fetal abnormalities
3. Women who received steroids within the preceding week We will invite women who meet the enrollment criteria to participate in the study, and perform an OGTT.

Research objectives:

1. Primary endpoints:

   The percentage of obese women with late GDM diagnosis will be divided into two groups according to BMI:
   * BMI 30-35 kg/m2
   * BMI \>35 kg/m2
2. Secondary endpoints:

   * Differences in the following obstetric outcomes between women diagnosed or not diagnosed with GDM: percentage of macrosomia, delivery method, shoulder dystocia, grade 3-4 tear
   * Differences in the following newborn outcomes between women diagnosed or not diagnosed with GDM: hypoglycemia, jaundice, need for phototherapy, polycythemia, hospitalization in neonatal intensive care, Apgar score, and newborn pH

Research procedure, interpretation of results, and patient follow-up:

* The OGTT involves assessing fasting blood glucose, drinking a solution comprising 100 g of glucose, and three glucose tests at one, two, and three hours following glucose load.
* Interpretation of the OGTT result is performed according to Carpenter-Coustan criteria \[6\]
* Women who are not diagnosed with GDM will be discharged for continued follow-up for regular prenatal care and the reason for her hospitalization.
* Per standard of care (regardless of research involvement) women diagnosed with GDM will receive counseling by a dietitian and other key department staff and undergo a complete glucose curve (seven tests per day: fasting, before each of three meals, and two hours after each meal).
* If more than 30% of glucose tests are abnormal, the patient will receive standard drug treatment.
* Follow-up is usually performed for 1-2 days in the hospital ward, after which women are discharged to ambulatory follow-up at the Mother and Fetus Clinic of the medical center.

Statistical analysis:

The sample size was calculated using the chi square formula for comparing two groups.

In a previous study in which repeat OGTT was performed beyond week 32 after initially normal results at week 24-28, the diagnosis rate of GDM for the total sample was 10%. An effect size of 20% was considered significant between obese and morbidly obese women with alpha=0.05, power 80%. The calculated sample size was 124 (at least 62 obese and 62 morbidly obese women).

Eligibility Criteria:
Inclusion Criteria:

1. Women with normal OGTT at weeks 24-28
2. Women with BMI \>30 kg/m2

Exclusion Criteria:

1. Multiple pregnancy
2. Fetal defects
3. Women who received steroids within the preceding week