Relationship between 1-hour glucose challenge test results and perinatal outcomes.

Objective: To estimate the relationship between 1-hour 50 g glucose challenge test values and perinatal outcomes.

Methods: This was a secondary analysis of data from a multicenter treatment trial of mild gestational diabetes mellitus. Women with glucose challenge test values of 135-199 mg/dL completed a 3-hour oral glucose tolerance test. Mild gestational diabetes mellitus was defined as fasting glucose less than 95 mg/dL and two or more abnormal oral glucose tolerance test values: 1-hour 180 mg/dL or more; 2-hour 155 mg/dL or more; and 3-hour 140 mg/dL or more. Our study included untreated women with glucose challenge test values of 135-139 mg/dL and 140-199 mg/dL and a comparison group with values less than 120 mg/dL. Primary outcomes included a perinatal composite (stillbirth, neonatal death, hypoglycemia, hyperbilirubinemia, neonatal hyperinsulinemia, and birth trauma), large for gestational age (LGA, birth weight above the 90 percentile based on sex-specific and race-specific norms), and macrosomia (greater than 4,000 g).

Results: There were 436 women with glucose challenge test values less than 120 mg/dL and 1,403 with values of 135 mg/dL or more (135-139, n=135; 140-199, n=1,268). The composite perinatal outcome occurred in 25.6% of those with glucose challenge test values less than 120 mg/dL compared with 21.1% for values of 135-139 mg/dL and 35.3% for values of 140-199 mg/dL. Rates of LGA by group were 6.6%, 6.8%, and 12.4%, respectively. Rates of macrosomia by group were 7.8%, 6.1%, and 12.1%, respectively. Compared with glucose challenge test values less than 120 mg/dL, the adjusted odds ratios (ORs) (95% confidence intervals [CIs]) for values of 140-199 mg/dL were 1.48 (1.14-1.93) for the composite outcome, 1.97 (1.29-3.11) for LGA, and 1.61 (1.07-2.49) for macrosomia. For glucose challenge test values of 135-139 mg/dL, adjusted ORs and 95% CIs were 0.75 (0.45-1.21), 1.04 (0.44-2.24), and 0.75 (0.30-1.66), respectively. The subcategories with glucose challenge test values of 140-144 mg/dL and 145-149 mg/dL also were associated with an increase in selected outcomes when compared with those with values less than 120 mg/dL.

Conclusions: Glucose challenge test values of 135-139 mg/dL were not associated with adverse outcomes compared with values less than 120 mg/dL; however, glucose challenge test values of 140 mg/dL or more were associated with an increase in odds of the composite perinatal outcome, LGA, and macrosomia.