Type 1 diabetes in pregnancy: a comparative study of hybrid closed-loop systems, continuous glucose monitoring, and home blood glucose monitoring

Sinead Cadogan; Ailbhe McCarthy; David Fennell; Sarah McDonnell; Amy O; Jennifer Hogan; Brendan Kinsley

doi:10.1530/endoabs.115.OC13

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Endocrine Abstracts (2026) 115 OC13 | DOI: 10.1530/endoabs.115.OC13

IES2025 Oral Communications Oral Communications (14 abstracts)

Type 1 diabetes in pregnancy: a comparative study of hybrid closed-loop systems, continuous glucose monitoring, and home blood glucose monitoring

Sinead Cadogan ^1,2 , Ailbhe McCarthy ¹ , David Fennell ¹ , Sarah McDonnell ¹ , Amy O’Higgins ¹ , Jennifer Hogan ¹ & Brendan Kinsley ^1,2

Author affiliations

¹The Coombe Hospital, Dublin, Ireland; ²Mater Misericordiae University Hospital, Dublin, Ireland

Optimising glycaemic control in pregnancies affected by type 1 diabetes (T1D) is critical to improving maternal and neonatal outcomes. While continuous glucose monitoring (CGM) and hybrid closed-loop (HCL) insulin delivery systems are well established in the non-pregnant population, real-world evidence in pregnancy remains limited. We conducted a retrospective study of 84 pregnant women with T; ¹D attending a joint diabetes-obstetric clinic from January 2023 to June 2025. Participants were grouped according to diabetes management: multiple daily injections (MDI) with home blood glucose monitoring (HBGM) (n = 22), MDI with CGM (n = 37), or HCL systems (n = 25; Medtronic; ⁷⁸⁰G, n = 20; Tandem t:slim X 2, n = 5). Glycaemic control was assessed using HbA; ¹c and CGM-derived metrics, including time in range (TIR), time above range (TAR), and time below range (TBR), at booking and each trimester. Women using HBGM had significantly higher HbA; ¹c values throughout pregnancy compared with those using CGM or HCL (P < 0.05). No significant differences in HbA; ¹c or CGM metrics were observed between the CGM and HCL groups. Preterm delivery (<37 weeks) occurred significantly more often in the HBGM group (50%) than in the CGM (20.8%) and HCL (19.1%) groups (P < 0.05). Rates of large- or small-for-gestational-age infants, neonatal hypoglycaemia, NICU admission, and caesarean section did not differ between groups. Outcomes were comparable between CGM+MDI and HCL users, supporting flexibility in technology choice. These findings support the integration of CGM into routine antenatal care for women with T; ¹D and underscore the need for prospective studies to define optimal technology strategies in pregnancy.