TB Vaccine Linked to Better Type 1 Diabetes Control


THURSDAY, June 21, 2018 (HealthDay News) -- Could a vaccine from the early 1900s be the key to preventing serious diabetes complications? Maybe, say researchers from Harvard University and Massachusetts General Hospital.

A little more than three years after getting two tuberculosis shots four weeks apart, about 50 people with type 1 diabetes saw their long-term average blood sugar levels drop significantly -- and for at least five years.

"The gold standard in treating diabetes is to lower blood sugar. Lowering blood sugar changes quality of life and reduces the risk of complications," said the study's senior author, Dr. Denise Faustman.

"After 3.5 years we saw a pretty sharp drop in blood sugar to near normal, and it stayed down," said Faustman, director of Mass General's immunobiology laboratory.

"We're not claiming anyone will be insulin-free, but we lowered average blood sugar by more than 10 percent consistently for more than five years. And it's affordable," she added.

Plus, the people in the study were adults with long-standing type 1 diabetes -- for at least 10 years, Faustman said.

The vaccine has U.S. Food and Drug Administration approval. It's officially known as the bacillus Calmette-Guerin (BCG) vaccine. It has been used against tuberculosis for about 100 years, Faustman said.

The researchers used a measure called hemoglobin A1C that estimates blood sugar levels over two to three months. To prevent complications, the American Diabetes Association recommends most healthy people keep A1C at 7 percent or lower.

The treatment arm of the study focused on 12 people with type 1 diabetes -- nine were placed in the BCG group, while three more received a placebo. At the start of the study, the average A1C for the vaccine group was 7.4. At the end of year five it was 6.2, and by the end of year eight it was 6.7. In a placebo group, there was no improvement in A1C, the study authors said.

Type 1 diabetes is an autoimmune disease. That means the body's immune system mistakenly attacks a healthy part of the body. In type 1 diabetes, the immune system attacks the insulin-producing beta cells in the pancreas. Someone with the condition needs to take insulin through injections or via a small tube inserted in the skin and attached to an insulin pump.

Faustman said changes observed in two previous studies didn't seem to come from any usual pathways, such as increased insulin production or less insulin resistance. So the investigators looked for other possibilities.

They believe what's happening is a process called aerobic glycolysis that causes cells to use up more sugar. The process appears to shut down when blood sugar levels drop, preventing blood sugar levels from falling too low, which can be a problem, too.

Faustman said that this might mean the vaccine could be useful for people with type 2 diabetes as well.

Two diabetes experts who were not involved with the study offered their take on the research.

Dr. Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center in New York City, said one should take the current findings "with a grain of salt." He said it's too early to know how effective this vaccine might be for any type of diabetes.

"We need more solid information," Zonszein said.

Dr. Mary Pat Gallagher is director of the Pediatric Diabetes Center at Hassenfeld Children's Hospital at NYU Langone Health in New York City.

"The design of the study doesn't provide any information about the cause of the decrease in hemoglobin A1C seen in this small group of subjects, and it is possible that it may be related to other factors," Gallagher said.

She said there are a number of ways to significantly lower A1C, including going on an insulin pump or starting to use a continuous glucose monitor (CGM).

This study, Gallagher added, "provides support for a potential mechanism through which BCG therapy might affect glucose control in people with type 1 diabetes, but it doesn't have any new information regarding the efficacy of this treatment." She noted that Faustman's team has a clinical trial going on that may provide more answers.

The study was published June 21 in the journal Vaccine.

More information

Learn more about type 1 diabetes from the U.S. Centers for Disease Control and Prevention.

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