Diabetes: Rethinking risk and the Dx that fits

2 abnormal results needed for a GDM diagnosis

In the absence of unequivocal hyperglycemia, there are 2 diagnostic standards for GDM: The Carpenter-Coustan Conversion and the National Diabetes Data Group Conversion. The Carpenter-Coustan Conversion uses lower glucose values for fasting (≥95 mg/dL) and subsequent 1-, 2-, and 3-hour levels (≥180, 155, and 140 mg/dL, respectively) and is more widely used. But expert opinion also supports the National Diabetes Data Group Conversion criteria (fasting plasma glucose, ≥105 mg/dL; ≥190, 165, and 145 mg/dL for 1-, 2-, and 3-hour OGTT, respectively), and there are no data from clinical trials to prove the superiority of either standard.³⁰

Both sets of standards require 2 or more thresholds to be met or exceeded for a GDM diagnosis. Women with only 1 abnormal value should be monitored carefully, however, as they, too, may be at increased risk for macrosomia and other morbidities.³⁰

Postpartum follow-up. Obtain a fasting glucose reading or perform an OGTT around the time of the postpartum checkup for any patient who was diagnosed with GDM. ACOG recommends using an OGTT to more accurately diagnose type 2 diabetes or prediabetes in these patients, who are at significantly elevated risk.³⁰

Acknowledgement

The authors wish to thank Carol Hildebrandt, a research assistant with no potential conflict of interest, for her help with this manuscript.

Correspondence
Julienne K. Kirk, PharmD, CDE, Department of Family and Community Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1084; jkirk@wfubmc.edu