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TB vaccine story for t1 triggers cautionary statement

Earlier this month a story announcing research about the tuberculosis vaccine helping people living with type 1 diabetes was widely covered in the international media - but the reporting of the facts has been questioned.

 

The American Diabetes Association (ADA) and JDRF on Tuesday issued a joint statement clarifying the findings and their importance to diabetes research.

 

According to the research from Massachusetts General Hospital, which was originally published in the journal npj Vaccines, a common vaccine for tuberculosis (the Bacillus Calmette-Guérrin, or BCG, vaccine) could improve type 1 diabetes by permanently lowering blood sugar levels.

 

Lead researcher Dr Denise Faustman and her team examined data on 282 individuals, 52 of whom had type 1 diabetes and participated in the BCG clinical trials and 230 of whom contributed blood samples.

 

Those participating in the clinical trials (average duration of their diabetes was 19 years) were given the vaccine twice four weeks apart and then studied for about eight years following treatment.

 

Regular monitoring throughout the eight-year study found the HbA1c levels of individuals receiving the vaccine dropped by more than 10 per cent at the three-year mark and by more than 18 per cent after four years of treatment. These levels reached near-normal figures five years after treatment.

 

HbA1c refers to glycated haemoglobin, which develops when haemoglobin, the red blood cell protein that carries oxygen throughout the body, is combined with glucose in the blood.

 

Participants treated with BCG were found to have an average HbA1C of 6.65 per cent four years later.  The threshold for diabetes diagnosis is on average close to an HbA1c of 6.5 per cent.

 

Tuesday's ADA and JDRF statement urged caution:

 

"While this work has attracted attention, the study only followed a very small number of patients - nine people at the five-year time point, and three people at the eight-year time point - and must be interpreted with caution.

 

Overall, the findings prompt through-provoking questions but not definitive answers, and do not provide enough clinical evidence to support any recommended change in therapy at this time.

 

Specific limitations that should be considered include:

 

  • All study participants continued to use standard insulin therapy throughout the trial; it's not a situation whereby the treatment changed their standard of care (all vaccinated individuals remained on insulin therapy).
  • The patients with reported positive outcomes achieved only moderately lower HbA1cs, which, while marginally statistically significant, cannot be generalized to the millions of people living with t1d and is not established to be as a result of the vaccination.
  • The article doesn't account for the natural variability in HbA1c levels over time, which is well known to occur in this population: they tend to improve in people with t1d as they age, particularly as they move out of their teens and early 20s. It's unclear what role natural history may have played in these subjects.
  • There is no detail on the standard of care in the BCG treated and control group. For example, was the care comparable between both study groups or were adjunctive therapies used?"

 

Diabetes Queensland is presenting this information to readers as a clear example of research that is faithfully presented to scientific communities being reported by mainstream media without the time, space or expertise to hedge research findings.

 

This organisation's commitment to you is to present the latest information and work with all organisations to achieve a cure for diabetes. We will continue to report all research news, but we urge readers not to invest false hope in generic news.

 

When a cure for diabetes is announced, we promise to be on the front foot to let you know about it. In the meantime, the research and the hunt continues.  

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