Medical review by Dr. Elizabeth Gomez
A new study has found that early-life use of the BCG vaccine—used across the world to prevent tuberculosis—may reduce the risks of type 1 and type 2 diabetes in adulthood.
The bacillus Calmette-Guérin (BCG) vaccine has been used to prevent tuberculosis for a century. It is one of the oldest, longest-studied, and best-understood vaccines. It is not necessarily perfectly effective against tuberculosis, but it is inexpensive and considered very safe. BCG is administered to as many as 100 million newborns across the globe annually, mostly outside of the western world. In today’s USA, it is only used in rare circumstances.
Although the BCG vaccine has never been used as a treatment for diabetes outside of experimental settings, there is some evidence that it may have a “beneficial impact on glucose metabolism.”
The new retrospective observational study, published as a pre-proof by the journal Diabetes & Metabolism, examined the medical records of several hundred thousand people born in Quebec in the early 1970s, about half of whom received the BCG vaccine for tuberculosis, typically in the first year of life. Those that received the vaccine were about 35% less likely to develop type 1 diabetes after the age of 30, and were also somewhat less likely to develop type 2 diabetes, although no beneficial effect was found for LADA.
The BCG vaccine had no apparent association with the development of type 1 diabetes before the age of 30, which is when most patients develop the condition.
While the study cannot prove that the BCG vaccine caused the positive results—and nobody is yet suggesting that it should once again be administered to infants in the United States or Europe—it is nevertheless another piece of the puzzle suggesting that BCG may have some applicability for people with diabetes, especially type 1 diabetes.
In the diabetes research community, the BCG vaccine is most strongly associated with the work of Dr. Denise Faustman.
In 2018, Dr. Faustman’s laboratory released the first results from a Phase I trial in which the BCG vaccine was administered to adults with long-standing type 1 diabetes. The numbers were extremely encouraging: patients who received just two doses of the BCG vaccine, spaced four weeks apart, achieved markedly lower A1c levels when compared to a control group. This result was first observed three years after the vaccine administration and continued for the next five years of follow-up. Participants receiving the experimental treatment had an HbA1c of just 6.18%, significantly lower than participants who received a placebo (7.07%).
These results understandably created a lot of enthusiasm in the diabetes community, but also generated controversy. The American Diabetes Association and JDRF took the unusual and dramatic step of co-authoring a joint statement to highlight “limitations” to Dr. Faustman’s research, and stressing that her work did “not provide enough clinical evidence to support any recommended change in therapy at this time.”
The criticism has not phased Dr. Faustman—in an interview with Diabetes Daily, she described it as evidence that “I’ve got something good.” Larger trials of the therapy are being conducted right now.
I reached out to Dr. Faustman for a comment on the new study, and here’s how she replied:
The results published by Dr. Rousseau are another compelling data point for the BCG vaccine and diabetes. We have a long way to go as we unravel the many variables from this and other studies, including number of doses, age of administration, and strain of BCG, but as the number of controlled trials and epidemiologic studies increases we are getting a clearer idea of the potential of BCG to prevent and reverse type 1 diabetes.
Dr. Faustman also wished to draw attention to an upcoming conference of the BCG Working Group, which will be “convened to share BCG data across multiple autoimmune and infectious diseases.” Dr. Rousseau, the lead author of the new study, will be a participant.
A reminder to readers: this is a news article, for educational purposes only, and absolutely does not constitute personal or individual medical advice.
Read more about A1c, American Diabetes Association (ADA), bacillus Calmette-Guérin (BCG) vaccine, bcg, diabetes prevention, Intensive management, JDRF.