At a Glance

  • A few weeks ago, the FDA approved Tzield for use by children 8-17 with Stage 3 T1D (symptomatic).
  • Tzield is the first immunomodulating drug approved for T1D, and the first FDA-approved therapy for Stage 3.
  • It was previously approved for Stage 2 T1D (presymptomatic), potentially delaying progression to Stage 3 for up to 2 years.
  • The new approval potentially opens a much larger market for Sanofi: 64K new T1D diagnoses each year in the US, at $200K per treatment (patient cost may be covered by insurance).
  • Tzield in Stage 3 slightly reduces the amount of external insulin required. It does not decrease HbA1c levels, increase time in range, or reduce hypoglycemic events.
  • Tzield does not prevent or stop progression to full diagnosis.

June 24, 2026

On June 12, the FDA approved Sanofi’s Tzield (teplizumab) for a new indication: To delay declining insulin production in pediatric patients with Stage 3 T1D. Stage 3 is the final stage, when enough insulin-producing cells have been destroyed for blood sugars to become abnormal and the telltale symptoms of T1D appear.

This is the first FDA-approved therapy for stage 3 T1D.

This report looks at Tzield from the perspective of a parent of a newly diagnosed child. Many will be strongly encouraged by care providers to use Tzield, in part because it is the only option available that promises to modulate the disease.

However, there are pros and cons to using this protocol. This report hopes to provide both sides with balance and thoughtfulness so that one can make as informed a decision as possible. Ultimately, the decision is a deeply personal one.
 

What Is Tzield?

Tzield is a drug that slows the autoimmune attack. It is a manmade protein—a monoclonal antibody—that binds to the autoimmune T cells and ‘calms’ their attack on insulin-producing beta cells. As a result, for some people, it delays the progression of T1D to varying degrees.
 
It is administered by IV once daily for fourteen days at a clinic, or via a midline catheter at home (if approved). For patients younger than eight years old, each session takes two hours. For patients older than eight years old, it lasts about 30 minutes. The uninsured, out-of-pocket cost of Tzield is approximately $200,000.
 

Tzield for Stage 2

Tzield was initially approved by the FDA in 2022 for use in adults and pediatric patients aged eight years and older in Stage 2. In April 2026, it was expanded to include patients as young as one year old. Stage 2 is identified by a blood test showing at least two autoantibodies that indicate T1D. When administered during Stage 2, the published data state that the treatment may delay progression to Stage 3 by up to two years. Only people with immediate relatives who have T1D are typically tested for these antibodies.

There are a few important unknowns. One is the long-term side effects of altering a person’s immune system, for which there is not enough data to determine.  Another is whether the delay definitively reduces complications later in life.

The initial approval for Tzield was somewhat controversial. The decision was based on data from one clinical trial with a very small test group, seventy-six people, compared to several thousand participants usually required for a phase III pre-market trial.

It is important to reiterate that Tzield may delay but does not prevent or stop T1D. It is not a cure.
 

The New News: Tzield for Stage 3

Tzield received accelerated FDA approval for use in Stage 3 T1D. In this case, the FDA concluded that the benefits of preserving natural insulin, even if only modest, were sufficient to bring this product to market. In addition, there is a belief that near-term adverse events related to Tzield are well understood because the drug has been on the market for several years for Stage 2.

However, clinical testing will continue even as it is made widely available. After some period of time and additional data, and assuming there are no surprises, the FDA will reduce its requirement for ongoing testing.

The therapy received accelerated approval based on results from the previous phase III PROTECT trial. A new phase III trial, BETA-PRESERVE, will serve as the confirmatory study for full approval and is currently enrolling.

The PROTECT trial enrolled 338 people. 217 received Tzield, while 111 received a placebo.

Who Is a Candidate?

Anyone between the ages of eight and seventeen years old in Stage 3 is a candidate. It is unknown whether there is a post-diagnosis timing cut-off, but we presume that most people will start treatment within six weeks of diagnosis, like patients in the PROTECT trial.

Sanofi is looking to extend the age groups in BETA-PRESERVE. The trial is currently recruiting pediatric patients and adults aged one to twenty-five, aiming to enroll 723 people, with an end date of June 2028.

Key Trial Results

The most important positive result is that there was a modest delay in the decrease of natural insulin among those who received Tzield versus placebo. People who received Tzield needed about 22% less insulin than those who received a placebo. This is good, and a move in the right direction. However, it is a subtle rather than game-changing improvement. 

Below is a quick summary of the main measures.

External Insulin Use: Modest improvement

  • Those taking Tzield averaged 0.463 units/kg/day.
  • Those taking the placebo averaged 0.593 units/kg/day.

HbA1C: No significant impact

Time-in-Range: No significant impact

Hypoglycemic Events: No significant impact

C-peptide Levels: Higher

  • Those who received Tzield had higher C-peptide levels than those in the control group. This indicates that the Tzield group made more natural insulin and needed less external insulin.