A RETROSPECTIVE case-control study presented at EASD 2026 has found that women with gestational diabetes mellitus (GDM) who previously underwent bariatric surgery experience significantly better glycaemic control and fewer delivery complications than their non-surgical counterparts, though with a trend towards smaller babies.
Gestational diabetes remains one of the most frequent pregnancy complications, carrying well-documented risks for both mother and baby. While bariatric surgery is known to improve metabolic health and reduce GDM incidence in women with obesity, how it shapes outcomes once GDM does develop has been poorly characterised. Researchers at a tertiary hospital set out to close this gap, comparing perinatal outcomes in women with GDM according to whether they had a history of bariatric surgery.
The team conducted a retrospective analysis of 88 pregnant women with GDM treated between 2006 and 2024, matching 44 women with prior bariatric surgery 1:1 with controls by maternal age and pregestational BMI. Anthropometric, glycaemic and delivery data were compared using Fisher’s exact and Wilcoxon tests, with a secondary analysis restricted to insulin-treated women to capture more severe, unambiguous GDM cases.
Researchers found women with a surgical history had markedly lower rates of macrosomia (0% vs 13.6%; p=0.02), lower neonatal birth weight, and fewer caesarean sections (25% vs 47.7%; p=0.04). Third-trimester HbA1c was significantly lower in the bariatric surgery group (4.9% vs 5.6%; p<0.01), despite similar rates of insulin use and gestational weight gain. Rates of preeclampsia, NICU admission, congenital anomalies and prematurity did not differ between groups. However, small-for-gestational-age (SGA) newborns trended higher in the surgery group (27.3% vs 9.1%; p=0.05), reaching significance in the insulin-treated subgroup (4.3% vs 35.3%; p=0.02).
In summary, prior bariatric surgery appears to improve glycaemic control and reduce macrosomia and caesarean delivery in women who go on to develop GDM, but clinicians should remain alert to an increased risk of SGA newborns. The authors call for future tailored nutritional and glycaemic monitoring strategies specific to this growing patient population.
Reference
Estape M et al. Perinatal outcomes in women with gestational diabetes and a history of bariatric surgery: a case-control study. Abstract 1003. EASD 2026, 28 September-2 October, 2026.
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