Researchers from the University of Hong Kong (HKUMed) have uncovered a crucial link between high blood sugar levels and weakened immune defenses in patients with type 2 diabetes (T2D).
Their findings, published in Cell Metabolism, shed light on why T2D patients are more prone to severe viral infections and underscore the importance of maintaining good blood glucose control to protect against health risks.
In Hong Kong, T2D affects about one in ten adults and poses significant public health challenges. While advancements in treatment have improved outcomes for many, a large number of patients still struggle to manage their blood sugar levels effectively.
Those with poorly controlled diabetes (PC-T2D) are especially vulnerable to frequent and severe complications.
How High Blood Sugar Impairs Immunity
The body’s defense against viral infections relies heavily on the production of anti-viral T cells, particularly T Helper 1 (Th1) cells, which coordinate inflammatory responses to eliminate infected cells.
However, during the COVID-19 pandemic, researchers observed that T2D patients, particularly those with poorly controlled blood sugar, had a mortality risk three times higher than non-diabetic individuals.
The HKUMed research team, led by Professor Heidi Ling Guangsheng, Dr. Paul Lee Chi-Ho, and Professor Kathryn Tan Choon-Beng, investigated why high blood sugar weakens the immune system. They studied 40 blood samples from T2D patients treated at Queen Mary Hospital between 2022 and 2023.
Their analysis revealed a 40% reduction in the functionality of Th1 cells in PC-T2D patients compared to healthy individuals. In contrast, patients with well-controlled diabetes (WC-T2D) showed no such decline, highlighting the protective role of effective blood sugar management.
Further experiments with immune cell cultures and animal models revealed that elevated blood sugar disrupts the metabolism of CD4+ T cells, a key component of the immune system.
This disruption leads to the degradation of a vital transcription factor required for Th1 cell development, impairing their ability to fight infections.
Additionally, this dysfunction triggers chronic inflammation, further weakening the immune system and increasing susceptibility to various health issues.
Implications for Patients and Public Health
The findings underscore the importance of glycemic control in T2D patients. Those who manage their blood sugar levels effectively through medication, healthy lifestyles, and adherence to treatment plans can avoid the harmful effects of T cell dysfunction and bolster their immune defenses.
“This research highlights the critical need for T2D patients to maintain optimal blood sugar levels,” said Professor Heidi Ling. “A strong immune system not only protects against everyday infections but also reduces the healthcare burden during viral pandemics.”
Dr. Paul Lee added, “T2D patients are at greater risk of severe complications from infections like COVID-19 and influenza.
By understanding their blood sugar levels, particularly glycated hemoglobin (HbA1c), and following their prescribed treatments, patients can protect themselves from life-threatening conditions.”
A Path Forward for Better Care
This study opens the door to developing new treatments aimed at restoring immune function in T2D patients. By targeting the mechanisms of CD4+ T cell dysfunction caused by high glucose levels, researchers hope to create therapies that strengthen the immune system in vulnerable populations.
The findings also serve as a reminder for individuals with T2D to take an active role in managing their condition. Regular monitoring, adherence to medication, and lifestyle changes such as healthy eating and exercise remain the most effective strategies for preventing complications and maintaining overall health.
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The research findings can be found in Cell Metabolism.
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