Glucose Testing in GDM: Adherence to One- Versus Two-hour Postprandial Glucose Monitoring in Gestational Diabetics

Consented patients who are diagnosed with gestational diabetes will be randomized to either 1-hour or 2-hour postprandial blood glucose monitoring. A retrospective chart review from July 2020 until study commencement for patients from the same clinic will be used as a historical control group. This study will assess differences in adherence to testing.

Inclusion criteria

• Pregnant patients with singleton gestation who are ≥ 18 years of age.
• Diagnosis of GDM after 24 0/7 weeks.
• For diagnosing GDM, a two-step screening algorithm will be performed according to the American College of Obstetrics and Gynecologists.4 Specifically, a 1-hour 50-g glucose-loading test is given first. Plasma glucose levels between 140 and 200 mg/dL will be considered elevated. Confirmatory testing will then be performed using a 3-hour 100-g glucose tolerance test. Diagnosis was made when two of the four values were elevated. Abnormal glucose value thresholds are established via the criteria suggested by Carpenter and Coustan: fasting value ≥ 95 mg/dL, 1-hour ≥ 180 mg/dL, 2-hour ≥ 155 mg/dL, and 3-hour ≥ 140 mg/dL.9 Patients with a blood glucose level greater than 200 mg/dL after 1-hour 50-g glucose-loading test will be diagnosed with GDM without requirement for the 3-hour 100-g glucose tolerance test.

Exclusion criteria

• Type 1 pre-gestational diabetes
• Type 2 pre-gestational diabetes
• GDM diagnosed prior to 24 0/7 weeks gestation.