There is no approved vaccine for diabetes, but several vaccine-like immunotherapies are in clinical trials for type 1 diabetes, and one FDA-approved drug already delays its onset by about two years. For type 2 diabetes, vaccine research is even earlier, limited to animal studies. The short answer: not yet, but the science is closer than most people realize.
Why a Vaccine for Diabetes Is Even Possible
Type 1 diabetes is an autoimmune disease. Your immune system mistakenly attacks the insulin-producing cells in your pancreas, eventually destroying them. A traditional vaccine trains your immune system to attack a virus or bacterium. A diabetes “vaccine” would do something closer to the opposite: teach your immune system to stop attacking your own cells. Researchers call this approach immune tolerance, and it’s the foundation for nearly every experimental diabetes vaccine in development.
Type 2 diabetes works differently. It’s driven by insulin resistance and metabolic dysfunction, not an immune attack. That makes it a harder target for a vaccine, though researchers have found at least one creative workaround in animal models.
The One FDA-Approved Treatment That Delays Type 1
In November 2022, the FDA approved teplizumab (brand name Tzield), the first drug proven to delay the onset of type 1 diabetes in people at high risk. It is not technically a vaccine, but it works on the immune system in a related way, calming the immune cells that would otherwise destroy insulin-producing cells.
In clinical trials, people who received teplizumab went a median of 50 months before developing full-blown type 1 diabetes, compared to 25 months for those on placebo. That’s roughly two extra years of living without the disease and without needing insulin injections. The treatment is specifically for people in “stage 2” of type 1 diabetes, meaning they already have autoantibodies in their blood and early signs of blood sugar problems but haven’t yet needed insulin.
The side effect profile is significant. Patients receiving teplizumab had notably higher rates of skin reactions (mostly rashes and minor infections), digestive symptoms like nausea, and temporary drops in certain white blood cell counts. That drop in immune cells is transient, resolving after the treatment course, but during that window patients are more susceptible to infections, particularly reactivation of Epstein-Barr virus. These trade-offs mean teplizumab isn’t a casual prescription. It’s reserved for people with confirmed autoantibodies and measurable progression toward diabetes.
The BCG Vaccine Approach
The BCG vaccine, originally developed over a century ago to prevent tuberculosis, has broad effects on the immune system that go beyond fighting a single infection. Researchers hypothesized that BCG could reprogram immune cells in a way that slows the autoimmune destruction seen in type 1 diabetes. In animal models, BCG suppressed the inflammation that damages insulin-producing cells, and early human studies showed intriguing signs: shifts in immune cell populations and changes in how the body processes glucose.
The clinical results so far, however, have been disappointing. A systematic review pooling data from four randomized controlled trials with 198 total participants found no significant improvement in long-term blood sugar control or insulin production in BCG-treated groups compared to placebo. Blood sugar markers trended slightly better in the BCG group, but the difference was too small to be meaningful. BCG remains an area of interest, but the evidence doesn’t yet support it as a treatment for type 1 diabetes.
GAD Vaccines Show Promise in a Genetic Subgroup
One of the most advanced true vaccine candidates targets a protein called GAD65, which is one of the molecules the immune system attacks in type 1 diabetes. The idea is straightforward: by introducing a carefully formulated version of this protein, you can retrain the immune system to tolerate it rather than attack it.
In a phase 2b trial, this approach was injected directly into lymph nodes of people recently diagnosed with type 1 diabetes. The results were striking, but only in a specific genetic subgroup. People carrying a particular immune gene variant (HLA DR3-DQ2) who received the GAD vaccine lost their insulin-producing capacity about 28% over 15 months, compared to a 58% decline in the placebo group. That’s roughly half the rate of destruction. Across a broader meta-analysis of multiple trials, the treatment effect in this genetic subgroup was a 48% preservation of insulin production for those receiving three or four injections.
A phase 3 trial (called DIAGNODE-3) is now underway across multiple countries to confirm these results in a larger population. If it succeeds, this could become the first true vaccine-style treatment for type 1 diabetes, though it would likely only work for the subset of patients with the right genetic profile.
Oral Insulin as a Preventive Vaccine
Giving insulin by mouth doesn’t lower blood sugar the way an injection does. Instead, it exposes the gut immune system to insulin as a protein, potentially teaching the body to tolerate it. The concept is essentially an oral vaccine against the autoimmune process.
The largest test of this idea, the Primary Oral Insulin Trial (POInT), screened nearly 242,000 newborns across Europe and identified about 1,050 infants with elevated genetic risk for type 1 diabetes. Half received daily oral insulin starting between 4 and 7 months of age, with doses gradually increasing until age 3. The other half received placebo. The treatment was safe and well-tolerated, with no episodes of low blood sugar.
Overall, it didn’t work. About 10% of children in the insulin group developed autoantibodies (the earliest marker of type 1 diabetes), compared to 9% in the placebo group, a negligible difference. But buried in the data was an interesting genetic split: children with one version of a specific insulin gene appeared to benefit, with a 62% reduction in risk, while children with a different version actually did worse on oral insulin. This suggests the approach might work for some children but not others, and any future use would require genetic testing to identify who would benefit.
Inverse Vaccines: Retraining the Immune System
A newer concept called “inverse vaccines” or “tolerogenic vaccines” takes a more direct approach to reprogramming immunity. Rather than broadly suppressing the immune system, these vaccines aim to generate specialized regulatory cells that specifically shut down the attack on insulin-producing cells while leaving the rest of your immune defenses intact.
In animal studies, two variations of this approach have shown remarkable results. One version, combining insulin with genetic material encoding its precursor protein, prevented diabetes progression in 93.8% of diabetes-prone mice for nearly a year. Another version, pairing a fragment of insulin with an immune-suppressing compound, protected 83.3% of mice from developing high blood sugar over 35 weeks. Both approaches worked by boosting the population of regulatory immune cells that keep inflammation in check, specifically targeting the pancreas without weakening overall immunity. These results are preclinical, meaning they haven’t been tested in humans yet, but the concept of antigen-specific tolerance is considered one of the most promising long-term strategies.
A Vaccine Concept for Type 2 Diabetes
Type 2 diabetes research has also produced a vaccine candidate, though it’s still in animal studies. This approach targets an enzyme called DPP4, which breaks down a gut hormone that helps your body release insulin after meals. Drugs that block this enzyme are already widely prescribed for type 2 diabetes, but they require daily pills.
Researchers designed a vaccine that trains the immune system to produce antibodies against DPP4, essentially achieving the same effect as a daily pill but with a single vaccination course. In mice, the vaccine successfully reduced DPP4 activity, raised levels of the beneficial gut hormone, and improved insulin sensitivity. The antibody response lasted about three months per dose. In diabetic mouse strains, vaccination significantly improved blood sugar control and increased insulin production, all without triggering harmful autoimmune reactions.
The appeal is obvious: replacing a daily medication with occasional injections. But the gap between mouse studies and human treatments is wide, and no human trials have been announced.
Other Immunotherapies in the Pipeline
Beyond vaccines specifically, several immune-targeting drugs are in phase 2 trials for type 1 diabetes. These include antibodies that block specific inflammatory signals involved in the immune attack on the pancreas, as well as a drug currently used for psoriasis and Crohn’s disease that targets two key immune pathways. These aren’t vaccines in the traditional sense, but they share the same goal: interrupting the autoimmune process before it destroys too many insulin-producing cells.
How to Know If You’re Eligible
Most of these preventive treatments require evidence that the autoimmune process has already started but hasn’t yet caused full diabetes. That evidence comes from blood tests for autoantibodies, proteins your immune system produces when it begins targeting pancreatic cells. Four autoantibodies are routinely tested: insulin autoantibodies, GAD autoantibodies, IA-2A autoantibodies, and ZnT8 autoantibodies. Having two or more of these is considered stage 1 type 1 diabetes, even if your blood sugar is completely normal.
Screening is most relevant if you have a first-degree relative with type 1 diabetes, since your risk is 10 to 15 times higher than the general population. Several research networks and organizations offer free or low-cost autoantibody screening for family members. If autoantibodies are detected, you may be eligible for clinical trials of preventive therapies or, if you’ve progressed to stage 2, for treatment with teplizumab.