Short and long-term outcomes after gestational diabetes diagnosis using different glycemic criteria: a systematic review and meta-analysis.

CONTEXT: Lower gestational diabetes (GDM) diagnostic criteria on an oral glucose tolerance test are widely recommended, but their impacts on maternal, neonatal, long-term and economic outcomes remain uncertain. OBJECTIVE: To compare outcomes after GDM diagnosis using lower versus higher diagnostic strategies. METHODS: We searched for randomized controlled trials (RCT) and prospective cohort studies comparing outcomes following assessment for GDM and treatment if indicated, using lower versus higher glycemic diagnostic criteria or thresholds in four databases and four trial registries (PROSPERO registration CRD420251183179) to 27th July 2026. Two reviewers independently assessed risk of bias, conducted random-effects meta-analyses and evaluated GRADE certainty. RESULTS: Seventeen studies were included, with nine RCTs and one cohort study contributing to the meta-analysis (81,528 women). Lower diagnostic criteria or thresholds, compared with higher diagnostic criteria or thresholds, doubled GDM diagnosis and pharmacotherapy use, increased neonatal hypoglycemia (RCTs: 18 more per 1,000; 95% CI 11 to 25 more) and maternal-neonatal separation (RCTs: 6 more per 1,000; 95% CI 1 to 12 more), but had little to no effect on other short-term outcomes. Longer-term evidence was limited to follow-up of one RCT reporting reduced maternal hypertension and child neurodevelopmental impairment but increased subsequent GDM at five-year follow-up with use of lower criteria or thresholds. Findings on GDM-related healthcare costs were inconsistent, with no long-term economic data. CONCLUSIONS: Lower diagnostic criteria increased the diagnosis of GDM and some aspects of healthcare utilization, without improving short-term outcomes. Limited evidence suggested possible longer-term benefits, warranting further long-term follow-up from high-quality RCTs.