Baricitinib (JAK1/2 inhibitor)

Screening: finding T1D before it strikes

Type 1 diabetes develops along a defined three-stage path, and that staging model is what makes early treatment possible at all. Stage 1 is two or more islet autoantibodies (against insulin, GAD, IA-2, or ZnT8) with normal blood glucose and no symptoms; stage 2 adds abnormal glucose (dysglycemia) but still no symptoms; stage 3 is clinical disease, when insulin is needed.¹ The autoantibodies are powerful predictors: once a child has two or more, the lifetime risk of clinical diabetes approaches certainty, which is why antibody panels (sometimes paired with genetic-risk scoring) are the basis of screening.¹ Most people who screen positive have no family history, so finding them at scale means general-population testing rather than only testing relatives.¹ Detecting T1D early is valuable even before any drug is given: people identified through screening are monitored, so when they reach stage 3 they are far less likely to arrive in diabetic ketoacidosis (DKA), a dangerous and sometimes fatal emergency.¹ Screening is also what creates the candidates for a therapy like baricitinib — without it, almost everyone is found only at diagnosis.

Therapy: an oral pill to slow the immune attack

Baricitinib is a once-daily oral JAK1/2 inhibitor. The immune attack on insulin-producing cells runs through the JAK-STAT pathway, which carries the inflammatory cytokine signals that recruit and activate the destructive T cells and make beta cells more visible to them; blocking JAK1/2 dampens that signalling. In mouse models of T1D, JAK1/2 inhibition prevented and even reversed new-onset diabetes — the rationale for testing it in people.²

The key human evidence is BANDIT (ACTRN12620000239965), an investigator-initiated phase-2 randomized, double-blind, placebo-controlled trial. 91 people aged 10–30, within 100 days of a stage-3 diagnosis, took baricitinib 4 mg/day or placebo for 48 weeks (2:1).³ At 48 weeks, the body's own insulin production — measured as mixed-meal-stimulated C-peptide — was 0.65 nmol/L/min with baricitinib versus 0.43 with placebo (P=0.001).³ Treated participants also needed less insulin (0.41 vs 0.52 U/kg/day) and had steadier glucose (lower variability on continuous monitoring), though average HbA1c was similar.³ A 2025 network meta-analysis of 42 immunotherapies placed baricitinib among the 11 with significantly higher 12-month C-peptide than placebo — credible, but one of several active candidates rather than a clear front-runner.⁴

Durability is the main caveat. BANDIT kept following participants for a year after the drug stopped, and the gap between groups progressively narrowed until they converged — so the benefit behaves like ongoing suppression that must be taken continuously, not a one-and-done reset.⁵ That reframes it as a long-term medication.

Safety: in BANDIT, adverse events matched placebo and no serious adverse events were attributed to the drug.³ But baricitinib's class carries an FDA boxed warning — serious infections, blood clots, certain cancers, major cardiovascular events, and mortality — based on long-term use in older arthritis patients.⁶ Those risks weigh more heavily when the plan is to treat a young, otherwise-healthy person for years.

Approval and access: baricitinib is approved (as Olumiant) for rheumatoid arthritis, severe alopecia areata, and hospitalized COVID-19 — but not for T1D, so any diabetes use today is investigational/off-label.⁶ Its appeal is the delivery: a cheap, oral, already-manufactured pill, in contrast to infused antibody therapies.

What's coming

Eli Lilly has launched two phase-3 trials. BARICADE-PRESERVE (NCT07222332) tests baricitinib at new-onset (stage 3, within 100 days), with C-peptide at 52 weeks as the primary endpoint.⁷ BARICADE-DELAY (NCT07222137) pushes earlier — into at-risk stage 1b/2 autoantibody-positive people — to see whether the pill can delay clinical onset, the true prevention question BANDIT could not answer; both enroll from age 1 to under 36.⁸ If either succeeds, baricitinib would become a rare oral, low-cost option in a field dominated by infusions — but the open questions of lifelong dosing and class safety will decide how widely it can responsibly be used.⁵

References

1. Sims EK, et al. Screening for Type 1 Diabetes in the General Population: A Status Report and Perspective. Diabetes (2022). https://doi.org/10.2337/dbi20-0054 ↩ ↩² ↩³ ↩⁴

2. Waibel M, et al. Investigating the efficacy of baricitinib in new onset type 1 diabetes mellitus (BANDIT) — study protocol. Trials (2022). https://doi.org/10.1186/s13063-022-06356-z ↩

3. Waibel M, et al. Baricitinib and β-Cell Function in Patients with New-Onset Type 1 Diabetes. N Engl J Med (2023). https://doi.org/10.1056/NEJMoa2306691 ↩ ↩² ↩³ ↩⁴

4. Beese SE, et al. A systematic review and network meta-analysis of interventions to preserve insulin-secreting beta cell function in newly diagnosed type 1 diabetes. BMC Med (2025). https://doi.org/10.1186/s12916-025-04201-z ↩

5. Baricitinib preserves C-peptide in patients with type 1 diabetes (reporting BANDIT off-drug follow-up, Kay TWH et al., EASD 2025). Healio (2025). https://www.healio.com/news/endocrinology/20250922/baricitinib-preserves-cpeptide-in-patients-with-type-1-diabetes ↩ ↩²

6. OLUMIANT (baricitinib) US prescribing information. FDA (2022). https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/207924s006lbl.pdf ↩ ↩²

7. BARICADE-PRESERVE: A Phase 3 Study of Baricitinib to Preserve Beta Cell Function in Newly Diagnosed Type 1 Diabetes (NCT07222332). ClinicalTrials.gov (2025). https://clinicaltrials.gov/study/NCT07222332 ↩

8. BARICADE-DELAY: A Phase 3 Study of Baricitinib to Delay Stage 3 Type 1 Diabetes in At-risk Participants (NCT07222137). ClinicalTrials.gov (2025). https://clinicaltrials.gov/study/NCT07222137 ↩