Challenging the Gold Standard: Pilot Study Comparing Continuous Glucose Monitoring System (CGMS), Capillary Glucose Monitors and 3 Hour Glucose Tolerance Test (GTT) to Diagnose Gestational Diabetes Mellitus (GDM)

The rate of gestational diabetes and fetal macrosomia is increasing. Moreover, it appears that many macrosomic infants are born to non-diabetic mothers. However, this presents the question of whether our current accepted means of diagnosis is reflecting the true prevalence of GDM. The 3-hour GTT measures glycemic control over a limited period of time. A more prolonged period of monitoring makes more physiologic sense, as it would paint a picture of a patient's overall trend before a diagnosis can be confirmed or excluded. Given the ability of the CGMS and capillary glucose monitor to follow glycemic trends over an extended time period, these methods may prove more effective at identifying patients with abnormal glucose tolerance. As these modalities test the patients in their native environments, the effect of dietary changes prior to the testing period may be minimized, potentially providing an more accurate assessment of abnormal glucose utilization. Furthermore, both modalities should be more cost-effective than the 3- hour GTT.

Inclusion criteria

• Pregnant patients seen in the Center for Women's Health at University Hospital in Cincinnati, Ohio between 24-28 weeks gestation
• One hour 50-g Glucose Challenge Test (GCT) value greater than 130 mg/dL.

Exclusion criteria

• Patients with known diabetes mellitus
• Patients receiving steroids or oral terbutaline therapy
• Patients entering prenatal care later than 20 weeks gestation