Most people think of type 1 diabetes mainly as a daily balancing act with blood sugar and insulin.
The focus is usually on complications, treatments and prevention.
A new line of research hints at something far more surprising happening in the body at the same time.
A new study in The Journal of Immunology suggests that the high blood sugar seen in type 1 diabetes may push a key part of the immune system to attack certain cancers more aggressively.
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The work was done in mice and backed up in human immune cells.
Doctors have long noticed something unusual. People with type 1 diabetes develop some cancers less often than the rest of the population, including breast cancer, colon cancer and melanoma, a form of skin cancer. Until now, no one really knew why.
The mouse experiments
The research team used mice with experimentally raised blood sugar.
Tumors of melanoma, breast cancer, lung cancer and colon cancer all grew more slowly in these animals compared with mice whose blood sugar stayed normal.
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The protective effect depended on the high blood sugar itself. When the researchers gave the mice insulin to bring sugar levels back to normal, the slowdown disappeared.
They traced the change to CD8+ T cells. These are immune cells that enter tumors and attack cancer cells. In the high-blood-sugar mice, these cells were more plentiful and better armed.
The team then checked immune cells from people with high blood sugar and found the same change, which strengthens the signal from the mouse experiments.
Why this is not a reason to welcome diabetes
Type 1 diabetes is a serious lifelong disease. Over the years it raises the risk of heart disease, kidney failure, nerve damage and vision loss.
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The condition is also linked to a higher overall risk of several other cancers.
These include stomach, lung, pancreas, liver, ovary and kidney cancers, according to a 2018 meta-analysis in the Japanese Journal of Clinical Oncology.
The new work does not change any of that. What it offers is a possible explanation.
The authors argue that if scientists can copy the immune boost without the diabetes, they may be able to design new cancer immunotherapies that borrow from the effect.
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Any such treatment is years away. The findings come from mice and from laboratory samples, not from clinical trials in cancer patients.
Human studies would need to show that the mechanism works the same way in people with cancer and that it can be safely harnessed without harming blood sugar control.
People with type 1 diabetes should continue to manage their condition as usual. Insulin remains essential, and no one should change their treatment based on this animal research.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.