Effect of Automated Insulin Delivery Using Hybrid Closed Loops in the Preconception, Peripartum and Postnatal Periods for Women with Type 1 Diabetes

Jones C, et al. J Diabetes Sci Technol. 2025 May 28:19322968251338863. Epub ahead of print. PMID: 40433847; PMCID: PMC12119519.

This single-center, retrospective observational study evaluated the impact of hybrid closed-loop (HCL) insulin delivery systems on glycemic control in women with type 1 diabetes (T1D) during preconception, pregnancy, and postnatal periods. Conducted at the University Hospitals of Leicester NHS Trust, the study included 47 women who initiated HCL preconception and 43 who used HCL during pregnancy. Key findings include:

• Preconception HCL initiation significantly reduced HbA1c from 62.4 to 54.2 mmol/mol (7.9% to 7.1%) within 3–6 months and increased time-in-range (TIR; 3.9–10.0 mmol/L) from 49% to 72% at six months. Time-below-range (TBR) also decreased significantly.
• Pregnancy HCL initiation led to a reduction in HbA1c from 61.2 to 48.1 mmol/mol (7.8% to 6.6%) and improved pregnancy-specific TIR (TIRp; 3.5–7.8 mmol/L) from 37% to 57% within one week, sustained through three months.
• Postnatal HCL use maintained glycemic control with TIR around 70% and low TBR (~2%).
• No significant differences in pregnancy outcomes (e.g., preterm birth, LGA, NICU admission) were observed between preconception and pregnancy HCL initiators, though preterm birth was numerically lower in the preconception group (25% vs. 46%).  

The authors conclude that HCL systems offer rapid and sustained improvements in glycemic control across all reproductive stages in women with T1D, including those from diverse ethnic and socioeconomic backgrounds. The findings support the integration of HCL into preconception counseling and diabetes management during and after pregnancy.