Characteristics of patients with abnormal glucose challenge test and normal oral glucose tolerance test results: comparison with normal and gestational diabetic patients.

Objective: The purpose of this study was to evaluate the characteristics and outcomes of patients who had abnormal glucose challenge test results and subsequent normal oral glucose tolerance test results and to assess whether such patients are at a greater risk than normal pregnant patients for adverse perinatal outcome.

Study Design: In this retrospective cohort study that was conducted between June and December 2003, 101 pregnant women (group A) had an abnormal glucose challenge test result and a normal oral glucose tolerance test result. Data were also collected on 2 control groups: 100 pregnant women with normal glucose challenge test results (group B) and all 76 pregnant women who were diagnosed with gestational diabetes mellitus during this period of time (group C). Patients with multiple pregnancies, chronic hypertension, pregestational diabetes mellitus, or any other maternal or fetal problems that were diagnosed before 24 weeks (when the glucose challenge test was performed) were excluded from the study groups. The following data were collected and analyzed: maternal age, maternal weight and height, parity and gravidity, diabetes mellitus in first-degree relatives, medical and obstetric history, ethnicity, complications during the third trimester of pregnancy, birth weight, gestational age at delivery, mode of delivery, Apgar scores, cord blood gas results, maternal complications of labor and during the postpartum period, and infant admission to the neonatal intensive care unit. For comparison between groups, we used the Student t test, 1-way analysis of variance, the chi-square test, and stepwise logistic regression.

Results: Patients in groups A and C were significantly older compared with group B (29.2 +/- 5.6 years and 30.4 +/- 5.5 years, respectively, vs 24.8 +/- 5.5 years; P < .01), had a lesser rate of primiparity (48% and 31%, respectively, vs 24%; P < .05), had greater body mass index (30.8 +/- 5 kg/m2 and 31.3 +/- 6 kg/m2, respectively, vs 29.2 +/- 4.4 kg/m2; P < .01), had a greater rate of previous gestational diabetes mellitus (6% and 20%, respectively, vs 0%; P < .05), and had a greater rate of first-degree family members with diabetes mellitus (21% and 21%, respectively, vs 3%; P < .01). None of the outcome parameters was statistically significant when group A was compared with group B.

Conclusion: Patients with an abnormal glucose challenge test result and a subsequent normal oral glucose tolerance test result have different maternal characteristics and backgrounds compared with patients in whom both test results are normal, yet both groups have normal outcomes. We should continue to consider patients who have an abnormal glucose challenge test result and subsequent normal oral glucose tolerance test result as low-risk; however, these findings may represent an indication of an increased likelihood for the development of overt diabetes mellitus later in life.