Hybrid closed-loop insulin system keeps blood sugar in check from pregnancy to postpartum

For pregnant women with type 1 diabetes (T1D), continued use of hybrid-closed loop (HCL) insulin through the postpartum period appears to be safe and efficacious, helping maintain blood sugar control for a significant portion of the time without an increase in hypoglycaemia.

In the prespecified extension of the AiDAPT trial, the percentage of time participants spent with their glucose levels within the target range (time in range [TIR] 3.9–10.0 mmol/L or 70–180 mg/dL) in the 6 months postpartum follow-up was 72 percent with HCL vs 54 percent with standard insulin therapy with CGM (standard care). This corresponded to a treatment difference of 15 percent (95 percent confidence interval [CI], 7–22). [Lancet Diabetes Endocrinol 2025;doi:10.1016/S2213-8587(24)00340-1]

Of note, participants in the HCL group demonstrated stable mean percentage TIR, from 73 percent in early pregnancy to 72 percent throughout the 6-month postpartum period. In contrast, those in the standard care group saw a decrease, from 70 percent to 54 percent, respectively.

“Differences in glycaemia were apparent from the first 4 weeks postpartum and in each subsequent 4-week period following delivery, with consistently higher TIR for the HCL group,” the investigators said.

“Glycaemic improvements were met by a marked reduction in maternal hyperglycaemia, especially evident overnight, and the improvements were not accompanied by an increase in hypoglycaemia,” they added.

The 6-month change in mean glucose levels was 1.3 mmol/L (95 percent CI, –2.3 to –0.3) lower with HCL vs standard care. Furthermore, participants in the HCL vs standard care group spent less time above both level 1 (10.0 mmol/L; 26 percent vs 42 percent) and level 2 (13.9 mmol/L; 7 percent vs 15 percent) hyperglycaemic thresholds.

Meanwhile, hypoglycaemia rates were low and did not differ between the two treatment groups in the 6-month postpartum follow-up (2.4 percent vs 2.6 percent). One case of severe hypoglycaemia occurred in the standard care group, and one case of device-related adverse events in the HCL group. No episodes of diabetic ketoacidosis were recorded in either group.

“The AiDAPT trial established the efficacy of HCL therapy during T1D pregnancy with glycaemic benefits over and above CGM with standard insulin therapy. Our current findings support continued use of HCL from pregnancy into the postpartum period,” the investigators said. [N Engl J Med 2023;389:1566-1578]

Postpartum: A time of increased risk

In an accompanying editorial, Australia-based experts emphasized the importance of the results for new mothers with T1D who may struggle in daily management of glucose levels in the postpartum period, since maintaining blood sugar control during this period is complicated by the profound physiological changes that occur after delivery and the lifestyle changes associated with caring for a newborn. [Lancet Diabetes Endocrinol 2025;doi:10.1016/S2213-8587(24)00374-7]

“The postpartum period presents a rapid physical and emotional change for the new parents, with new responsibilities and little personal time. While recovering from childbirth, mothers also often experience fatigue, sleep deprivation, stress, and erratic nutrition—sometimes while breastfeeding,” wrote Drs David O’Neal from the University of Melbourne and Glyniss Ross from the University of Sydney.

“The superimposition of T1D with the need to self-manage insulin dosing adds a further challenge. Decisions made in the postpartum state might not be optimal and unsurprisingly, the postpartum is characterized by glycaemic instability and an increased risk for hypoglycaemia,” O’Neal and Ross added.

Indeed, in the lived experience feedback, participants in the standard care group highlighted the difficulties they encountered during the postpartum period and how it affected their diabetes management. One participant reported: “My glucose control during pregnancy was probably the best it had ever been, then since giving birth it's been all over the show with the new (and huge) lifestyle changes, irregular eating patterns and breastfeeding.”

On the other hand, those in the HCL group emphasized how the HCL benefitted them. One participant feedback read: “Breastfeeding and sleepless nights were much easier to manage while on closed loop system. I had no concerns about my BG and was able to focus on my recovery and caring for a newborn.” Another stated: “Having that mental headspace and freedom to not be thinking about my blood sugars all the time has allowed me to focus on my child and the value of that can't be underestimated.”

However, O’Neal and Ross acknowledged that despite the promising results of the AiDAPT extension study, meaningful progress will be ultimately limited by lack of access to automated insulin delivery systems and the necessary support services among women faced with the significant challenges associated with managing their glucose levels during pregnancy and the postpartum period.

“We urgently need to secure funding for these devices and to resource healthcare professional support enabling access to these new and life-changing technologies benefiting two generations. AiDAPT provides essential evidence in support of the case for equity in access,” they said.