Highlights
- The RADIANT trial demonstrates a significant HbA1c reduction of 0.8% when transitioning directly from multiple daily injections (MDI) to tubeless automated insulin delivery (AID) compared to continuing MDI.
- Safety outcomes were robust, with zero episodes of diabetic ketoacidosis (DKA) or severe hypoglycemia reported in the AID group over 13 weeks.
- Direct transition from MDI to AID simplifies the clinical workflow, offering a viable therapeutic option for patients with suboptimal glycemic control (HbA1c 7.5–11.0%).
- Integrating genetic susceptibility data suggests that metabolic interventions are increasingly critical as environmental factors exacerbate glycemic instability in predisposed populations.
Background
Type 1 diabetes (T1D) management has evolved from rudimentary insulin replacement to sophisticated sensor-augmented therapies. Despite these advances, a substantial proportion of children and adults fail to meet glycemic targets using multiple daily injections (MDI), even when combined with continuous glucose monitoring (CGM). Suboptimal control, characterized by an elevated HbA1c, remains a primary driver of long-term microvascular and macrovascular complications.
Automated insulin delivery (AID) systems—often referred to as ‘closed-loop’ systems—integrate CGM data with algorithms to modulate insulin delivery via a pump. While traditional tethered (tubed) pumps have shown efficacy, ‘tubeless’ or patch-pump AID systems offer reduced catheter-related issues and improved patient discretion. Until recently, randomized controlled data specifically evaluating the direct transition from MDI to tubeless AID in populations with elevated HbA1c were sparse. The RADIANT trial (PMID: 41747751) addresses this critical evidence gap, providing a multicentre, international perspective on the safety and efficacy of this therapeutic shift.
Key Content
The RADIANT Trial: Study Design and Participant Demographics
The RADIANT trial was a 13-week, multicentre, open-label, randomized, controlled trial conducted across 19 sites in the United Kingdom, Belgium, and France. The study enrolled 188 participants (adults and children aged 4–70 years) who were currently managing T1D with MDI and CGM but maintained an HbA1c between 7.5% and 11% (58–97 mmol/mol). This specific cohort represents a ‘real-world’ clinical challenge: patients who are engaged with technology (CGM) but struggle to achieve target levels through manual dosing.
Participants were randomized in a 2:1 ratio to either the tubeless AID group (Omnipod 5) or the control group (continued MDI). This design allowed for a robust comparison of a technological upgrade versus the current standard of care. The primary endpoint was the change in HbA1c at 13 weeks, adjusted for baseline values and age.
Efficacy and Glycemic Outcomes
The findings of the RADIANT trial were statistically and clinically significant. The AID group experienced a mean reduction in HbA1c from 8.1% (65 mmol/mol) at baseline to 7.2% (55 mmol/mol) at 13 weeks. In contrast, the control group’s HbA1c remained virtually stagnant, moving from 8.1% to 8.0%. The adjusted mean difference of -0.8% (95% CI -1.0 to -0.6; p<0.0001) confirms the superiority of the tubeless AID system.
Beyond HbA1c, the rapid improvement in the AID group suggests that the algorithm effectively manages both basal requirements and postprandial excursions more efficiently than manual MDI, even in patients who were already familiar with their glucose trends via CGM. The reduction to 7.2% brings a high-risk population much closer to the internationally recognized target of <7.0%, significantly lowering the projected risk for future complications.
Safety and Tolerability Profile
Safety is a paramount concern when introducing automated algorithms that can increase insulin delivery. In the RADIANT trial, no episodes of severe hypoglycemia or DKA occurred in either group. This is particularly noteworthy for the AID group, as it suggests the system’s hypoglycemia-suspension and auto-bolus features are well-calibrated for a broad age range. Adverse events in the AID group (39 events in 28 participants) were more frequent than in the control group, though most were related to the skin-borne nature of the patch pump or typical device-related issues. Two serious adverse events (Kawasaki disease and acute coronary syndrome) were determined to be unrelated to the AID system itself.
Broader Perspectives: Genetic and Comorbidity Contexts
The necessity for advanced glycemic control is underscored by recent population studies. The HUNT study (PMID: 41619756) highlights that the gap in diabetes prevalence between the most and least genetically susceptible individuals is widening. This suggests that as the environment becomes more ‘diabetogenic,’ those with a genetic predisposition to dysglycemia require more aggressive and precise management—such as AID—to maintain metabolic health.
Furthermore, the clinical impact of diabetes extends into other therapeutic domains. For instance, in patients with Aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-IgG NMOSD), diabetes mellitus was identified as a potent independent predictor for severe and opportunistic infections (OR 7.48, PMID: 41618998). This emphasizes that in the modern clinical landscape, T1D management is not just about glucose; it is a critical component of risk stratification for infectious and inflammatory comorbidities.
Expert Commentary
The RADIANT trial provides high-level evidence supporting a “direct-to-AID” approach for patients on MDI. Historically, many clinicians required a transitional period where a patient first learned to use a standard insulin pump (in manual mode) before activating AID algorithms. RADIANT demonstrates that this intermediate step may be unnecessary, potentially reducing the burden on clinical staff and accelerating the time to glycemic improvement for the patient.
However, several nuances remain. The open-label nature of the trial is a limitation, as participants in the AID group might have exhibited increased motivation due to the novel technology. Additionally, while the 13-week duration shows rapid efficacy, long-term sustainability and device ‘fatigue’ require further longitudinal study. From a health policy perspective, the cost-effectiveness of tubeless AID compared to MDI must be weighed against the significant reduction in potential complication-related costs suggested by an 0.8% HbA1c drop.
The integration of findings from the HUNT study and NMOSD research also suggests that we must view AID not as a luxury, but as a preventative necessity for those at high metabolic risk. The 7.48-fold increase in infection risk in diabetic NMOSD patients is a sobering reminder that poor glucose control compromises the entire immune and vascular system.
Conclusion
The RADIANT trial confirms that tubeless automated insulin delivery is a superior and safe alternative to multiple daily injections for children and adults with T1D and elevated HbA1c. The direct transition from MDI to AID is effective, resulting in an 0.8% absolute reduction in HbA1c over just three months without increasing the risk of DKA or severe hypoglycemia. As clinical guidelines continue to evolve, AID should increasingly be considered a first-line therapeutic option within the standard of care. Future research should focus on the long-term durability of these outcomes and the potential for AID to mitigate the risks associated with high genetic susceptibility and multisystemic comorbidities.
References
- Wilmot EG, et al. Tubeless automated insulin delivery versus multiple daily injections in children and adults with type 1 diabetes with elevated HbA1c (RADIANT): a multicentre, international, parallel-group, open-label, randomised, controlled trial. Lancet Diabetes Endocrinol. 2026. PMID: 41747751.
- HUNT Study Group. Temporal changes and genetic susceptibility to type 2 diabetes (1984-2019; HUNT): a longitudinal, population-based study. Lancet Diabetes Endocrinol. 2026. PMID: 41619756.
- UK National Specialist Service. Predictive factors for immunosuppression-associated severe and opportunistic infections in AQP4-IgG Neuromyelitis Optica Spectrum Disorder. Mult Scler. 2026. PMID: 41618998.