Delayed maturation of the milk microbiome in women with type 1 diabetes – published online 30/06/2026

Alexandra J. Roth‑Schulze, Katrina M. Ngui, Guinevere Martin, Pat Ashwood, Rebecca L. Thomson, Enrique Zozaya‑Valdes, Yuan Gao, John M. Wentworth, Maria E. Craig, Anthony Huynh, Jennifer J. Couper, Megan A. S. Penno, Leonard C. Harrison, for the ENDIA Study Group

The human milk microbiome is an important contributor to early-life gut microbial colonisation and immune system development, but little is known about how it is influenced by type 1 diabetes. In this issue, Roth-Schulze et al (https://doi.org/10.1007/s00125-026-06791-6) investigate whether maternal type 1 diabetes alters the breastmilk microbiome. Breastmilk samples from 69 women with type 1 diabetes and 49 women without type 1 diabetes were analysed by 16S rRNA sequencing at several timepoints from birth to 15 months postpartum, alongside stool samples from their infants. The authors report that women with type 1 diabetes showed delayed early maturation of the breastmilk microbiome, with slower increases in microbial diversity and delayed enrichment of taxa such as Streptococcus spp. and Rothia mucilaginosa, which contribute to milk oligosaccharide metabolism and infant gut immune development. These differences were independent of Caesarean delivery, BMI, parity, infant sex and breastfeeding initiation, and were not associated with maternal genetic risk, HbA_1c or milk secretory IgA. Infants of mothers with type 1 diabetes showed early compositional differences in gut microbiota, but these did not persist. The authors conclude that further investigation is required to determine whether these transient changes in infant gut colonisation affect development of the infant’s gut and immune system.