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


Tita, Alan T. N.; Lai, Yinglei; Landon, Mark B.; Ramin, Susan M.; Casey, Brian M.; Wapner, Ronald J.; Varner, Michael W.; Thorp, John M., Jr.; Sciscione, Anthony C.; & Catalano, Patrick M., et al. (2017). Predictive Characteristics of Elevated 1-Hour Glucose Challenge Test Results for Gestational Diabetes. American Journal of Perinatology, 34(14), 1464-1469. PMCID: PMC5685869


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.


Reference Type

Journal Article

Year Published


Journal Title

American Journal of Perinatology


Tita, Alan T. N.
Lai, Yinglei
Landon, Mark B.
Ramin, Susan M.
Casey, Brian M.
Wapner, Ronald J.
Varner, Michael W.
Thorp, John M., Jr.
Sciscione, Anthony C.
Catalano, Patrick M.
Harper, Margaret A.
Saade, George R.
Caritis, Steve N.
Sorokin, Yoram
Peaceman, Alan M.
Tolosa, Jorge E., for the
Eunice Kennedy Shriver
National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units (MFMU) Network