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Why are diabetics at an increased risk of infection?

Scientists have shown that people with type 1 diabetes have less of a type of protein that signals other immune cells to fight infections. This makes them more susceptible to illness.


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Image Credit: Photo by Towfiqu barbhuiya on Unsplash

People with type 1 diabetes are high risk individuals because they have a weakened immune system, meaning they often get sick. Type 1 diabetes occurs when the pancreas fails to produce enough insulin, so people with Type 1 diabetes have to rely on insulin shots. Insulin helps blood sugar enter our cells, which is later used for energy. 

People with type 1 diabetes have a difficult time fighting off viruses, bacteria, and other microorganisms that cause disease in the body, referred to as pathogens. But researchers still don’t know exactly why type 1 diabetics often lose this fight. 

An international team of researchers recently proposed that the correlation between type 1 diabetes and disease susceptibility could be linked to proteins in the bloodstream. To test this, they examined people’s blood to see how their proteins responded to three types of bacterial pathogens. 

The team recruited 299 participants, including 243 people with type 1 diabetes and 56 healthy people. They tested three different pathogens: Candida albicans, Staphylococcus aureus, and Mycobacterium tuberculosis. The scientists combined the three types of pathogens with blood samples from each of the patients.

The scientists hypothesized that small proteins in the blood, called cytokines, could be responding to these pathogens in different ways in people with diabetes. Cytokines are the proteins that call other immune cells to the site of infection. They are cell messengers that help to regulate the body’s response to a pathogen and how well it fights off infections.

To examine cytokine production, the researchers had to isolate special blood cells that contain immune cells, called peripheral blood mononuclear cells (PMBCs). They isolated the PMBCs by spinning the blood samples in a centrifuge, which separated the PMBCs from plasma and other components of the blood. The scientists combined the isolated PMBCs with the three different pathogens and measured how many cytokines were in each mixture. 

After 24 hours, the scientists compared the amount of cytokines produced in response to each pathogen in blood samples from participants with diabetes versus in healthy participants. The blood from diabetic participants had fewer cytokines in the blood mixtures with C. albicans and S. aureus than in healthy blood. On the other hand, blood samples from diabetic participants with M. tuberculosis had the same amount of cytokines as blood samples from healthy participants. 

The team suggested that these results meant that individuals with type 1 diabetes generally produce less cytokines than healthy individuals. The types of cytokines that the scientists measured all play a role in starting an inflammatory response against bacterial and fungal pathogens. So they proposed that this decrease in cytokine production could be why people with type 1 diabetes are more susceptible to these types of illnesses. 

This study offers the first step to understanding how cytokine production affects the immune system of type 1 diabetics, but questions remain. These researchers suggested that future work could look for other factors that decrease cytokine production, such as age, sex, and environmental factors. They also suggested that studies like these could help develop new drug treatments to increase cytokine production in type 1 diabetics. 

Study Information

Original study: Understanding the Increased Risk of Infections in Diabetes: Innate and Adaptive Immune Responses in Type 1 Diabetes

Study was published on: May 5, 2021

Study author(s): Anna W.M. Janssen, Rinke Stienstra, Marin Jaeger, Alain J. Van Gool, Leo A.B. Joosten, Mihai G. Netea, Niels P. Riksen, Cees J. Tack

The study was done at: Radboud University Medical Center (Netherlands), Wageningen University and Research (Netherlands), Iuliu Hatieganu University of Medicine and Pharmacy (Romania), Life and Medical Sciences Institute (Germany)

The study was funded by: Perspectief Biomarker Development Center Research Programme

Raw data availability: Not available

Featured image credit: Photo by Towfiqu barbhuiya on Unsplash

This summary was edited by: Aubrey Zerkle