A 100-year-old vaccine for tuberculosis appears to lower blood glucose levels of patients with long-term type 1 diabetes to near normal and might have the potential to reverse type 2 diabetes. For the millions of patients with diabetes, that’s exciting news that could prompt inquiries about receiving the vaccine at your pharmacy.
While the vaccine is widely used in areas of the world with high rates of tuberculosis (TB), the CDC does not recommend its routine use in the United States for that purpose, and its use in diabetes remains in the clinical-trial stage.
Still, the results of studies recently presented at the American Diabetes Association 78th Scientific Sessions and published in npj Vaccines have sharply increased interest in the vaccine’s novel use as a means to lower blood glucose levels for years and to potentially reverse type 1 and type 2 diabetes.
In a study that involved 282 participants, 52 of whom had long-standing type 1 diabetes, researchers found that 3 years after immunization with the two doses of the BCG vaccine administered 4 weeks apart, HbA1c levels dropped more than 10% in the diabetic patients. By Year 4, they experienced an 18% reduction in HbA1c—and sustained that reduction for the next 4 years.
The researchers noted that the mean HbA1c of 6.65 brought patients who received the BCG vaccine quite close to the 6.5 threshold point for diabetes diagnosis. Patients who received a placebo and a reference group with type 1 diabetes maintained a mean HbA1c of 7.22 throughout the 8-year study.
Patients who received the vaccine reported no severe hypoglycemia, despite maintaining low blood glucose levels, while those who did not receive the vaccine continued to experience hypoglycemic events. All participants maintained their regular diabetes care throughout the study, including use of insulin pumps or continuous glucose-monitoring devices.
The research team, led by Denise Faustman, MD, PhD, director of the MGH Immunobiology Laboratory, principal investigator of BCG clinical trials at Massachusetts General Hospital, determined that the vaccine lowered blood glucose levels by shifting glucose metabolism from oxidative phosphorylation to aerobic glycolysis, which increases cells’ consumption of glucose. They also found that BCG reduced blood sugar in mice that had hyperglycemia triggered by causes other than autoimmune attack, which indicated that it might also be beneficial in type 2 diabetes.
The researchers cautioned in a question and answer document accompanying a news release from Massachusetts General that the results of the study are preliminary and further research is needed. “We do not recommend that anyone take BCG for diabetes nor do we recommend any 'off label' use of BCG. These results are reports from clinical trials and should not be confused with approval from the FDA,” they said.
Eight additional trials have enrolled hundreds of patients to see whether the results hold up in a larger population.
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