COVID-19 pandemic: Can fasting plasma glucose and HbA1c replace the oral glucose tolerance test to screen for hyperglycaemia in pregnancy?

Aims: To evaluate proposals considering HbA1c and fasting plasma glucose (FPG) measurement as a substitute for oral glucose tolerance test (OGTT) to diagnose hyperglycaemia in pregnancy (HIP) during COVID-19 pandemic.

Methods: Of the 7,334 women who underwent the OGTT between 22 and 30 weeks gestation, 966 had HIP (WHO diagnostic criteria, reference standard). The 467 women who had an available HbA1c were used for analysis. French-speaking Society of Diabetes (SFD) proposal to diagnose HIP during COVID-19 pandemic was retrospectively applied: HbA1c ≥5.7% (39 mmol/mol) and/or FPG level ≥5.1 mmol/l. SFD proposal sensitivity for HIP diagnosis and the occurrence of HIP-related events (preeclampsia, large for gestational age infant, shoulder dystocia or neonatal hypoglycaemia) in women with false negative (FN) and true positive (TP) HIP-diagnoses were evaluated.

Results: The sensitivity was 57% [95% confidence interval 52-62]. FN women had globally lower plasma glucose levels during OGTT, lower HbA1c and body mass index than those TP. The percentage of HIP-related events was similar in FN (who were cared) and TP cases, respectively 19.5 and 16.9% (p = 0.48). We observed similar results when women at high risk for HIP only were considered.

Conclusion: The SFD proposal has a poor sensitivity to detect HIP. Furthermore, it fails to have any advantages in predicting adverse outcomes.