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Phase 2CompletedNCT04774224

BANDIT: Baricitinib (JAK inhibitor) in recent-onset type 1 diabetes

A phase 2 randomized, placebo-controlled trial testing whether baricitinib — an oral JAK1/JAK2 inhibitor already used for rheumatoid arthritis — can protect the body's own insulin production when started within 100 days of a type 1 diabetes diagnosis. Over 48 weeks it preserved C-peptide versus placebo, the first oral immune-modifying drug to show this benefit in new-onset disease.

Primary endpoints

  • Mean C-peptide level (a marker of the body's own insulin production), measured as the area under the curve during a 2-hour mixed-meal tolerance test, at week 48

Results so far

Baricitinib preserved the body's own insulin production. At 48 weeks the median stimulated mean C-peptide was 0.65 nmol/L/min in the baricitinib group versus 0.43 in the placebo group (P=0.001). Daily insulin need was lower with baricitinib (0.41 vs 0.52 U/kg/day) and glucose was more stable on continuous monitoring (variability 29.6% vs 33.8%), though average HbA1c was similar. Side effects were similar to placebo, with no serious adverse events attributed to the drug.

The full picture

What was tested and why it matters

In type 1 diabetes, the immune system mistakenly attacks the insulin-making beta cells in the pancreas. A key relay system inside immune cells, called the JAK-STAT pathway, helps drive that attack.1 Baricitinib is a pill that blocks two of those relays (JAK1 and JAK2). It is already approved for rheumatoid arthritis, and in lab models it both prevented and reversed newly diagnosed diabetes in mice.1 The BANDIT trial asked a simple, important question: could this existing oral drug, given soon after diagnosis, slow the immune-driven loss of insulin-making cells in people?2

This matters because most current treatments only replace insulin; they do not protect the cells the body still has. Holding on to even a little of your own insulin production makes blood sugar steadier and lowers the risk of complications.1

Who it was for

The trial enrolled people aged 10 to 30 who had been diagnosed with type 1 diabetes within the previous 100 days and still had measurable insulin-making function.2 It ran across centres in Australia.2

How it was designed

BANDIT was a phase 2, double-blind, randomized, placebo-controlled trial.3 Ninety-one participants were assigned in a 2-to-1 ratio to baricitinib 4 mg once daily (60 people) or matching placebo (31 people) for 48 weeks.3 Neither participants nor staff knew who received the drug.4 The main measure was the body's own insulin output — C-peptide — during a standardized "mixed-meal" test at 48 weeks.3

Key results

Baricitinib preserved insulin-making function. At 48 weeks the median stimulated C-peptide was 0.65 nmol/L/min with baricitinib versus 0.43 with placebo (P=0.001).3 People on baricitinib also needed less injected insulin (0.41 vs 0.52 units/kg/day) and had steadier glucose on continuous monitoring (variability 29.6% vs 33.8%).3 Average HbA1c was similar between the groups.3 Importantly, side effects were no more common than with placebo, and no serious adverse events were attributed to the drug.3

What it means and what's next

BANDIT was the first trial to show that an oral, already-available drug can protect insulin-making cells in newly diagnosed type 1 diabetes — a more convenient approach than the infusions used for other immunotherapies.3 The authors note this supports testing baricitinib in combination with other therapies, and in people at risk before diagnosis, to try to prevent the disease.1 Follow-up work has since explored simple clinical scores to identify who responds best to such immunotherapy.5

References

  1. Waibel M, Thomas HE, Wentworth JM, et al. Investigating the efficacy of baricitinib in new onset type 1 diabetes mellitus (BANDIT) — study protocol for a phase 2, randomized, placebo controlled trial. Trials (2022). https://doi.org/10.1186/s13063-022-06356-z ↩ ↩2 ↩3 ↩4

  2. ClinicalTrials.gov. A Phase 2, Randomised, Placebo Controlled Study Investigating the Efficacy of Baricitinib in New Onset Type 1 Diabetes Mellitus (BANDIT). ClinicalTrials.gov (NCT04774224). https://clinicaltrials.gov/study/NCT04774224 ↩ ↩2 ↩3

  3. Waibel M, Wentworth JM, So M, et al. Baricitinib and β-Cell Function in Patients with New-Onset Type 1 Diabetes. N Engl J Med (2023);389(23):2140-2150. https://doi.org/10.1056/NEJMoa2306691 ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  4. ClinicalTrials.gov. BANDIT study design — randomized allocation, quadruple masking (participant, care provider, investigator, outcomes assessor). ClinicalTrials.gov (NCT04774224). https://clinicaltrials.gov/study/NCT04774224 ↩

  5. So M, Vogrin S, Waibel M, Kay TWH, Wentworth JM. β-Cell Function Derived From Routine Clinical Measures Reports and Predicts Treatment Response to Immunotherapy in Recent-Onset Type 1 Diabetes. Diabetes Care (2025);48(8):1370-1376. https://doi.org/10.2337/dc25-0565 ↩