September marks Polycystic Ovary Syndrome (PCOS) Awareness Month. PCOS is a common endocrine disorder, affecting around 13% of women of reproductive age in the UK. Characterised by hyperandrogenism, ovulatory dysfunction, and the presence of immature ovarian follicles, PCOS is associated not only with reproductive challenges but also with significant metabolic disturbances. One of the most concerning of these is the elevated risk of developing gestational diabetes mellitus (GDM) during pregnancy.
The Pathophysiological Link
Several mechanisms contribute to the increased risk of GDM in women with PCOS. Insulin resistance, a key factor in the development of GDM, affects up to 80% of women with PCOS. Excess adiposity, often driven by PCOS-related hormonal changes, amplifies this insulin resistance and creates a chronic pro-inflammatory state that disrupts glucose metabolism.
During pregnancy, the natural increase in insulin demands can overwhelm already impaired pancreatic β-cell function in women with PCOS, tipping them into hyperglycaemia and GDM. Elevated androgen and luteinising hormone levels further contribute by altering insulin signalling and β-cell performance.
Risks for Women and Babies
Gestational diabetes carries significant risks for both mother and baby, regardless of whether PCOS is present. Women with GDM are more likely to:
• Require insulin therapy during pregnancy due to increased insulin resistance.
• Develop pregnancy complications such as pre-eclampsia, preterm delivery, and the need for caesarean section.
• Face a higher lifetime risk of progressing to type 2 diabetes after pregnancy.
For babies, GDM increases the likelihood of higher birth weight (macrosomia), birth trauma, neonatal hypoglycaemia, and a long-term predisposition to obesity and metabolic disease. Since women with PCOS are already at greater risk of developing GDM, early detection and proactive care are especially important in this group to prevent complications and support healthier outcomes for both mother and child.
The Importance of Antenatal Care
Early screening and ongoing monitoring are essential. International guidelines recommend that women with PCOS undergo an oral glucose tolerance test (OGTT) early in pregnancy and repeat testing at the standard 24-28 weeks. The OGTT has superior accuracy compared to fasting glucose and HbA1c tests, ensuring timely diagnosis and the chance to intervene before complications escalate.
Lifestyle modification - focusing on nutrition, physical activity, and weight management - has been shown to reduce the risk and severity of GDM. However, women with PCOS often require more tailored support due to their underlying hormonal and metabolic challenges.
Multidisciplinary Management
Effective care for women with PCOS and GDM goes beyond routine monitoring. It requires input from multiple specialties working together:
• Primary care and endocrinology to address insulin resistance and long-term metabolic risks.
• Obstetrics and midwifery to closely monitor pregnancy progression and plan safe delivery.
• Dietitians and nutritionists to provide personalised dietary strategies that reduce glycaemic spikes.
This multidisciplinary approach ensures that care plans address both immediate pregnancy needs and the mother’s longer-term health, while also supporting neonatal outcomes.
Conclusion
Women with PCOS face a significantly higher risk of developing GDM and experiencing adverse pregnancy outcomes compared to women without PCOS. The combined impact of insulin resistance, hormonal imbalance, and increased metabolic demands underscores the importance of early testing, personalised lifestyle interventions, and collaborative care.