T1D Study: Common Vaccine Leads to Improvement in Blood Sugar Levels

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By : Suvarna Sheth

Break-through results in treating patients with type 1 diabetes in a long-term, Harvard and Massachusetts General Hospital study were published today.

Most notable about the news is that patients on the trial were not on a diabetes medication — but rather on an inexpensive, commonly used tuberculosis vaccine.

Three years after receiving the vaccine, called bacillus Calmette-Guérin (BCG), all adults in the trial with long-term type 1 diabetes showed an improvement in HbA1c to near-normal levels.  Improved blood sugar levels were seen for as long as eight years after treatment.

“This is clinical validation of the potential to stably lower blood sugars to near normal levels with a safe vaccine, even in patients with longstanding disease,” said Denise Faustman, M.D., Ph.D., principal investigator of the clinical trials at MGH and senior author of the report in a press release.

“In addition to the clinical outcomes, we now have a clear understanding of the mechanisms through which limited BCG vaccine doses can make permanent, beneficial changes to the immune system and lower blood sugars in type 1 diabetes,” she added in the release.

The results of the study are based on a small phase 1 trial with 282 participants – 52 with type 1 diabetes who participated in the BCG clinical trials and 230 who contributed blood samples.  A phase 2 clinical trial is underway to further study the most effective dosing regimes.

As to why BCG has beneficial effects on HbA1c levels, researchers identified a mechanism never seen before in humans:

“A shifting of the process of glucose metabolism from oxidative phosphorylation, the most common pathway by which cells convert glucose into energy, to aerobic glycolysis, a process that involves significantly greater glucose consumption by cells,” the press release explains.

Researchers also found that BCG could reduce blood sugar spikes in mice that had elevated blood sugar due to reasons other than an autoimmune problem.  This raises the possibility that BCG vaccines could also be beneficial against type 2 diabetes.

Faustman will present results of a separate group of BCG clinical trial participants with longstanding type 1 diabetes on Saturday, June 23, at the 78th Scientific Sessions of the American Diabetes Association in Orlando, FL.


  1. “BCG vaccine leads to long-term improvement in blood sugar levels in type 1 diabetes patients,” (18, June 21).  Retrieved June 21, 2018, from https://www.massgeneral.org/about/pressrelease.aspx?id=2262