Time-Varying Association of Acute and Post-Acute COVID-19 With Gestational Diabetes Mellitus

Objective: To investigate whether coronavirus disease 2019 (COVID-19) infection increases the risk of gestational diabetes mellitus (GDM) in pregnant women and to assess whether this risk persists beyond the acute phase of infection. Methods: A retrospective cohort study was conducted at Peking University First Hospital between January and February 2023, enrolling pregnant women who contracted COVID-19 between 16 and 32 weeks of gestation. The primary exposure was the time interval between the oral glucose tolerance test (OGTT) and the onset of COVID-19 infection. The primary outcome was the diagnosis of GDM based on OGTT results. A locally weighted scatterplot smoothing method was applied to visualize trends, and logistic regression was used to estimate odds ratios ( OR s). Results: The incidence of GDM increased from 23.1% in women who underwent OGTT before COVID-19 infection to 36.7% in those tested after infection ( P = 0.051). All OGTT values were elevated post-infection, with postprandial glucose levels showing the most pronounced rise. As the time since infection increased, OGTT values gradually normalized. The elevated risk of GDM decreased over time: OR for 1–2 weeks post-infection was 3.58 (95% CI : 1.27–10.23); 3–4 weeks: 2.47 (1.04–5.94); 5–6 weeks: 1.45 (0.44–4.41); and 7–8 weeks: 0.41 (0.08–1.55). Conclusion: COVID-19 infection was associated with a transiently increased risk of GDM, particularly within the first month following symptom onset, suggesting that the infection may have a short-term impact on glucose metabolism during pregnancy.