If you or someone you love has diabetes, you may have noticed that even small cuts or blisters on the feet can take weeks — or even months — to heal. This is not just bad luck. Scientists have now uncovered a fascinating reason: the immune system itself gets confused, and instead of helping wounds heal, it actually makes things worse.
A major new scientific review, published in MedScience in December 2025 by researcher Yi Ru and colleagues, brings together years of research to explain exactly what goes wrong inside a diabetic wound. The findings have important implications for anyone managing diabetes — and especially for foot care.
The Numbers Behind the Problem
Diabetic wounds affect more than 131 million people worldwide, and treatment costs reach an estimated $755 billion each year. These chronic ulcers — particularly on the feet — are one of the leading causes of amputation. Understanding why they don't heal is therefore not just a scientific curiosity; it's a matter of saving limbs and lives.
How Normal Wound Healing Works
When you get a cut, your body launches a carefully choreographed healing process:
- Inflammation phase — Immune cells rush to the wound to fight bacteria and clean up damaged tissue
- Repair phase — The body switches gears, calming inflammation and building new tissue
- Remodeling phase — The new tissue strengthens and matures
The key players in this process are macrophages — immune cells that act like the body's construction managers. Early on, they take an aggressive "M1" form that fights infection. Then, around day three, they transform into a gentler "M2" form that promotes healing and tissue repair.
This M1-to-M2 switch is one of the most critical moments in wound healing.
What Goes Wrong in Diabetes
Here is the problem: in diabetic wounds, the macrophages get stuck. They remain in their aggressive M1 state and never properly switch to the healing M2 state. Instead of calming down and rebuilding tissue, they keep producing inflammatory chemicals that damage the surrounding skin.
Think of it like a demolition crew that was supposed to hand the job over to builders — but the demolition crew never leaves. The builders can't get to work, and the construction site just keeps getting worse.
High blood sugar levels are a major driver of this problem. Excess glucose creates harmful molecules called AGEs (Advanced Glycation End-products) that disrupt the normal signaling between immune cells and essentially trap macrophages in their inflammatory state.
It's Not Just Macrophages
The review reveals that multiple types of immune cells malfunction in diabetic wounds:
- Neutrophils — normally the first responders — become overactive and release excessive amounts of damaging enzymes and reactive oxygen species
- Mast cells become excessively activated, sustaining the inflammatory environment
- Dendritic cells lose their ability to clean up dead cells (a process called efferocytosis), causing debris to accumulate and trigger more inflammation. Scientists have identified a specific transporter called SLC7A11 as a key regulator of this process
- Regulatory T cells, which normally calm inflammation, are fewer in number and work less effectively
- Dendritic epidermal T cells, specialized skin cells that produce growth factors for wound closure, show reduced activity
Hope on the Horizon: New Treatments
The good news is that understanding these immune mechanisms is opening the door to entirely new treatment approaches:
- Macrophage-targeting therapies — drugs that help push macrophages from the inflammatory M1 state to the healing M2 state. Several have already shown success in clinical trials
- Advanced wound dressings — new biomaterials designed to deliver immune-regulating compounds directly to the wound
- Stem cell therapies — mesenchymal stem cells and their secreted vesicles can provide multiple immune-regulating effects
- Personalized medicine — immune profiling of individual wounds could allow doctors to match the right therapy to the right stage of healing
What This Means for You
While these advanced therapies are still being developed, this research underscores something that podiatrists and foot care specialists have known for years: prevention and early intervention are absolutely critical for people with diabetes.
Here's what you can do right now:
- Check your feet daily — look for cuts, blisters, redness, or swelling
- Keep blood sugar under control — this directly affects your immune cells' ability to heal wounds
- Don't ignore small wounds — what seems minor can become serious quickly
- Get regular professional foot care — a trained foot care specialist can spot problems before they become dangerous
- Wear proper footwear — protect your feet from injuries in the first place
At ihohud Vaasa, we provide specialized diabetic foot care that includes monofilament and tuning fork testing to assess nerve function and circulation. Regular visits help us catch potential problems early — before they have a chance to become chronic wounds.
The Bottom Line
Science is revealing that diabetic wound healing failure is not simply about "bad circulation" or "high sugar." It is a complex immune system malfunction where multiple types of cells fail to do their jobs at the right time. This deeper understanding is paving the way for smarter, more targeted treatments.
In the meantime, the best strategy remains what it has always been: take care of your feet, control your blood sugar, and seek professional help at the first sign of trouble.
Sources
- Ru, Y. et al. (2025). "Immune cells in diabetic wound repair: the key to better wound management." MedScience, 19, 950-967. DOI: 10.1007/s11684-025-1190-y
- Maschalidi, S. et al. (2022). "Targeting SLC7A11 improves efferocytosis by dendritic cells and wound healing in diabetes." Nature. PubMed: 35614212
- Huang, Y.Y. et al. (2022). "Macrophage polarization in diabetic wound healing." Burns & Trauma. PMC9797953
- Louiselle, A.E. et al. (2021). "Macrophage polarization and diabetic wound healing." Translational Research. PubMed: 34089902
- Zhao, H. et al. (2022). "Macrophages as a therapeutic target to promote diabetic wound healing." PMC9482022
- Zhu, S. et al. (2024). "Epigenetic regulatory mechanism of macrophage polarization in diabetic wound healing." PMC11551531