Impact of Metabolic Surgery on Gestational Diabetes Mellitus: A Cohort Analysis.

Background: With the upsurge of obesity in Australia and worldwide, the incidence of metabolic surgery is increasing in women of reproductive age. Metabolic surgery reduces the rate of gestational diabetes mellitus, however, the risk remains about that for the general population.

Aim: To evaluate maternal and perinatal outcomes of consecutive women with GDM post-metabolic surgery presenting to an endocrine antenatal clinic in a single tertiary centre.

Methods: A retrospective cohort study of women with GDM after metabolic surgery were audited between 2020 and 2024.

Results: This cohort of 36 women were aged 32.9 (± 4.7) years and 3.3 (±2.0) years post-surgery with the majority undergoing sleeve gastrectomy (97.2%). Gestational diabetes was diagnosed at 25 (±6⁺⁰) weeks. Screening identified carbohydrate inadequacy or inconsistency (18/36, 50%) and micronutrient deficiency (34/36, 94.4%) were common, with 26/36 (72.2%) women deficient in more than one micronutrient. Insulin therapy was required in 16 women. Recurrent hypoglycaemia occurred in 10 (27.8%) women. Women birthed at 38 (±1⁺⁰) weeks, with unplanned Caesarean delivery in six (16.7%) women. Composite adverse neonatal outcomes occurred in 22/36 (61.1%) of births. Hypoglycaemia (< 2.6 mmol/L) occurred in 8/36 (22.2%) of neonates; 1/36 (2.8%) were small-for-gestational age, and 2/36 (5.6%) large-for-gestational age. A higher neonatal birthweight was observed in women with reported pre-pregnancy BMI ≥ 30 kg/m² and women requiring insulin.

Conclusion: Nutritional deficiencies occur commonly in women with gestational diabetes after metabolic surgery. There was a high rate of composite adverse neonatal outcome suggesting that these pregnancies may be higher risk. Further research is required to evaluate the optimal methods of screening and recommended glycaemic targets.