Objective: The purpose of this study was to determine the benefit of early glucose screening prior to 24 weeks' gestation in detecting gestational diabetes.
Study design: A retrospective analysis of 329 patients who received both early and complete prenatal care at the University of Illinois was performed. A 50-g, 1-hour glucose screen was performed at the first prenatal visit. An abnormal glucose screen, defined as blood sugar > 135 mg/dL, was followed by a 100-g, 3-hour glucose tolerance test. Gestational diabetes was defined as the presence of two or more abnormal values on the three-hour test. This protocol was repeated again at 28 weeks in all patients except those diagnosed as diabetic by having abnormal early three-hour tests. Data collected included maternal age, race, gravidity, presence of risk factors, pregnancy weight gain at glucose testing and delivery, neonatal birth weight and trauma. Data were analyzed using analysis of variance and chi 2 testing, with P < .05 considered significant.
Results: Gestational diabetes was diagnosed in 20 (6.1%) of the study patients. Eight (40%) of the gestational diabetics in the study population were detected with the early screening protocol. Factors associated with early detection of glucose intolerance included maternal age > 30 years (P < .001), black race (P < .001) and the presence of risk factors (P < .0001). Poor pregnancy weight gain was associated with the late development of glucose intolerance (P < .001). Gestational diabetes was subsequently diagnosed in 16% (6/38) of those patients who had, on early testing, an elevated one-hour glucose screen and negative three-hour glucose tolerance test when testing was repeated in the third trimester.
Conclusion: Early gestational glucose screening may be beneficial in detecting gestational diabetes in patients over 30 years old who are black or who have risk factors for diabetes. Consideration should be given to repeat glucose testing in the early third trimester in patients with false positive early one-hour screening tests.