Am J Perinatol 2017; 34(14): 1464-1469
DOI: 10.1055/s-0037-1604243
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Predictive Characteristics of Elevated 1-Hour Glucose Challenge Test Results for Gestational Diabetes

Alan T.N. Tita
1  Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, Alabama
Yinglei Lai
2  The Biostatistics Center, The George Washington University, Washington, District of Columbia
Mark B. Landon
3  Ohio State University, Columbus, Ohio
Susan M. Ramin
4  University of Texas Health Science Center, Houston-Children's Memorial Hermann Hospital, Houston, Texas
Brian Casey
5  University of Texas Southwestern Medical Center, Dallas, Texas
Ronald J. Wapner
6  Columbia University, New York, New York
Michael W. Varner
7  University of Utah, Salt Lake City, Utah
John M. Thorp Jr.
8  University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
Anthony Sciscione
9  Drexel University, Philadelphia, Pennsylvania
Patrick Catalano
10  MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio
Margaret Harper
11  Wake Forest University Health Sciences, Winston-Salem, North Carolina
George R. Saade
12  University of Texas Medical Branch, Galveston, Texas
Steve N. Caritis
13  University of Pittsburgh, Pittsburgh, Pennsylvania
Yoram Sorokin
14  Wayne State University, Detroit, Michigan
Alan M. Peaceman
15  Northwestern University, Chicago, Illinois
Jorge E. Tolosa
16  Oregon Health and Science University, Portland, Oregon
for the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units (MFMU) Network› Author Affiliations
Further Information

Publication History

20 January 2017

08 June 2017

Publication Date:
19 July 2017 (eFirst)


Objective The objective was to estimate the optimal screen-positive 1-hour 50 g glucose challenge test (GCT) threshold for gestational diabetes (GDM) and predictive characteristics of increasing screen-positive GCT threshold values (135–199 mg/dL) for GDM.

Study Design It is a secondary analysis of a multicenter mild GDM study. At 24 to 30 weeks' gestation, women with elevated GCT (135–199 mg/dL) completed a diagnostic 3-hour oral glucose tolerance test (OGTT). A novel change-point analysis method was used to compare the GDM rates for the adjacent GCT values, delineating categories of changing risk such that values within categories have equal risk for GDM. Positive (PPV) and negative (NPV) predictive values for GDM were computed for increasing GCT cut-offs.

Results In 7,280 women with both GCT (135–199 mg/dL) and OGTT results, 4 GDM risk-equivalent GCT categories were identified with escalations at 144, 158, and 174 mg/dL (all p-values <0.05). The PPV for GDM increased from 33 to 64% as GCT increased from 135 to 199 mg/dL, while the NPV decreased from 80 to 67%. PPVs were only 20% and 61% for risk-equivalent categories of 135 to 143 mg/dL and 174 to 199 mg/dL, respectively.

Conclusion Elevated GCT cut-off values between 135 and 143 mg/dL may carry equivalent GDM risk. No threshold GCT value <199 mg/dL alone sufficiently predicts GDM.


This study was presented in part as a poster presentation at the 31st Annual Meeting of the Society for Maternal-Fetal Medicine in San Francisco, CA February 9–12, 2011.