Gestational Diabetes Mellitus (GDM)
Why in news?
Gestational diabetes mellitus (GDM) is seeing major updates in global guidelines, early‑prediction tools, and precision‑medicine approaches as of 2024–2025.​
Global guideline and policy updates
- WHO issued its first global guideline on diabetes in pregnancy in 2025, covering type 1, type 2 and GDM with an end‑to‑end framework for screening, pharmacologic treatment, monitoring and health‑system readiness.​
- The guideline positions metformin (alone or with insulin) as a first‑line drug when lifestyle therapy fails in GDM and type 2 diabetes in pregnancy, and calls for structured ultrasound‑based fetal monitoring and selective early HbA1c use.​
Screening and classification advances
- Recent reviews emphasise “early GDM” (eGDM), defined as hyperglycaemia detected before 20 weeks that is not overt pre‑existing diabetes, noting that 30–50% of women normalize by 24–28 weeks but still carry higher adverse outcome risk.​
- The Australasian Diabetes in Pregnancy Society (ADIPS) 2025 consensus recommendations update criteria for screening, diagnosis and classification of hyperglycaemia in pregnancy, reflecting new evidence and aiming for region‑wide standardisation.​
Burden and India‑specific relevance
- The International Diabetes Federation estimates that about 23.3 million live births (15.6%) in 2024 were affected by some form of hyperglycaemia in pregnancy worldwide, underscoring GDM as a major global maternal‑health issue.​
- Commentaries applying the 2025 WHO guideline to India cite GDM prevalence around 13% among Indian pregnant women and nearly 30% conversion to type 2 diabetes postpartum, arguing for universal or highly proactive screening and integrated NCD–maternal health models.​
About GDM
- Gestational Diabetes Mellitus (GDM) is hyperglycemia diagnosed or developing during pregnancy in women without prior diabetes.
- It arises from pregnancy-induced insulin resistance, primarily due to placental hormones like human placental lactogen, combined with pancreatic β-cell dysfunction that limits insulin secretion.​
Causes and Risk Factors
- Placental hormones increase insulin resistance to prioritize fetal glucose supply, but in GDM, maternal β-cells fail to compensate adequately, leading to elevated blood glucose.
- Risk factors include obesity, advanced maternal age, family history of diabetes, and prior GDM.
- This mirrors type 2 diabetes pathophysiology but is pregnancy-specific.​
Diagnosis
- Screening typically occurs at 24-28 weeks via a 75g oral glucose tolerance test (OGTT), with cutoffs like fasting ≥92-126 mg/dL or 2-hour ≥140 mg/dL indicating GDM.
- Earlier testing applies for high-risk cases, such as at the first prenatal visit.​
Management
- First-line treatment involves medical nutrition therapy (diet) and exercise; insulin is added if targets aren't met, as it doesn't cross the placenta.
- Oral agents like metformin may be considered in some guidelines, but insulin remains preferred.​
Risks and Prognosis
- Untreated GDM raises risks of macrosomia, neonatal hypoglycemia, preeclampsia, and cesarean delivery; women face 7-fold higher type 2 diabetes risk postpartum.
- Treatment reduces complications, with postpartum OGTT screening recommended at 4-12 weeks.​
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