Can simpler blood tests identify high-risk pregnancies even when they miss many cases of gestational diabetes?

Details

Fasting glucose and glycated hemoglobin (HbA1c) were used to diagnose gestational diabetes during the COVID-19 pandemic. This study asked whether those diagnostic criteria might also have a role outside the pandemic.

This was a comparative diagnostic study with simultaneous testing, comparisons between groups, and regression analysis. From May 2022 to July 2024, 354 females with an abnormal 50-g oral glucose tolerance test (OGTT) underwent both the usual diagnostic test, the 100-g OGTT, and assessment using alternative diagnostic criteria (A): fasting glucose ≥ 95 mg/dL and/or HbA1c ≥ 5.7%. There were four groups: OGTT+/A+ (positive on both, n = 20), OGTT+/A− (positive only on the usual diagnostic test, n = 60), OGTT−/A+ (positive only on the alternative criteria, n = 24), and OGTT−/A− (negative on both, n = 250). The groups were compared for clinical characteristics and obstetric and perinatal outcomes.

The alternative criteria had a sensitivity of 25% and a specificity of 91.2%. Body mass index (BMI) was similar in the OGTT−/A+ and OGTT+/A+ groups: 30.1 ± 6.3 kg/m² and 32.7 ± 5.3 kg/m², respectively. BMI in these groups was significantly higher than in the OGTT+/A− and OGTT−/A− groups, which had values of 26.8 ± 5.1 kg/m² and 25.6 ± 5.0 kg/m², respectively.

Rates of large-for-gestational-age (LGA) infants followed a similar between-group pattern: OGTT+/A+, 38.9%; OGTT+/A−, 11.8%; OGTT−/A+, 29.4%; and OGTT−/A−, 12.4% (P = 0.028). In regression analysis, a history of macrosomia was independently associated with higher odds of LGA (odds ratio [OR] = 7.948, 95% confidence interval [CI]: 2.269–27.842; P = 0.001), as was higher pregestational BMI (OR = 1.069, 95% CI: 1.002–1.140; P = 0.042).

The researchers concluded that the alternative criteria were not valid enough to replace the OGTT. However, they identified a group of patients with a higher risk profile and adverse perinatal outcomes who might benefit from health interventions.