Researchers studied 169 patients with diabetic foot infections to understand how vitamin D levels affect their healing and infection severity. They found that 70% of these patients didn’t have enough vitamin D in their blood. Patients with low vitamin D had more inflammation, worse infection markers, and more bacteria forming protective layers (called biofilms) in their wounds. This suggests that vitamin D might play an important role in fighting these serious infections, and checking vitamin D levels could become part of treating diabetic foot problems.

The Quick Take

  • What they studied: Whether people with diabetic foot infections who have low vitamin D levels experience worse infections and more inflammation compared to those with normal vitamin D levels.
  • Who participated: 169 patients being treated for diabetic foot infections at a major hospital between September 2022 and March 2024.
  • Key finding: About 7 out of 10 patients with diabetic foot infections had low vitamin D levels. Those with the lowest vitamin D had significantly more bacteria forming protective layers in their wounds and higher inflammation markers.
  • What it means for you: If you have diabetes and develop a foot infection, your doctor might want to check your vitamin D levels as part of your care. Getting enough vitamin D could potentially help your body fight the infection better, though more research is needed to confirm this.

The Research Details

This was a cross-sectional study, which means researchers looked at a group of patients at one point in time rather than following them over months or years. They measured vitamin D levels in the blood of 169 patients with diabetic foot infections using a special lab test. They also measured two important proteins (VDR and LL-37) that help the body fight infections, and they tested how much bacteria in the wounds were forming biofilms—protective layers that make infections harder to treat. The researchers collected information about each patient’s health from their medical records, including blood sugar control, infection severity, and inflammation levels.

This research approach is useful because it shows whether vitamin D levels are connected to infection severity right now. By measuring multiple factors at the same time—vitamin D, immune proteins, bacterial behavior, and inflammation—the researchers could see the bigger picture of how vitamin D might affect the whole infection process. This type of study is good for identifying patterns that might be worth studying more deeply.

This study has some strengths: it measured vitamin D using a reliable lab method, it looked at multiple related factors (not just one thing), and it included a reasonable number of patients. However, because it’s a snapshot in time rather than following patients over time, we can’t be completely sure that low vitamin D causes worse infections—it could be that severe infections cause low vitamin D, or both could be caused by something else. The study was done at one hospital, so results might be different in other places or populations.

What the Results Show

The study found that vitamin D deficiency was extremely common in this group: 70.4% of patients had low vitamin D, 19.5% had borderline low levels, and only 10.1% had normal vitamin D. The average vitamin D level was quite low at 15.3 ng/mL (normal is usually 30 ng/mL or higher). Patients with the lowest vitamin D levels had significantly higher inflammation markers in their blood, meaning their bodies were mounting a stronger inflammatory response to the infection. These patients also had worse blood sugar control and more severe infection scores. Most importantly, bacteria from patients with low vitamin D were much more likely to form biofilms—tough, slimy protective layers that make infections harder to treat with antibiotics.

The study also measured two proteins that help the immune system fight infections: VDR (vitamin D receptor) and LL-37 (cathelicidin). Both of these were significantly lower in patients with vitamin D deficiency. These proteins are important because they help white blood cells recognize and destroy bacteria. When vitamin D is low, the body makes less of these protective proteins, which could explain why infections are worse. The research showed that 84% of bacteria from vitamin D-deficient patients formed biofilms, compared to much lower rates in patients with adequate vitamin D.

Previous research has suggested that vitamin D plays a role in immune function and fighting infections, but this is one of the first studies to look specifically at how vitamin D affects diabetic foot infections. The findings align with what we know about vitamin D’s role in immunity—it helps activate immune cells and produce antimicrobial proteins. This study adds to growing evidence that vitamin D deficiency might be a problem in people with diabetes and serious infections.

This study has several important limitations to keep in mind. First, it only shows that low vitamin D and worse infections are connected—it doesn’t prove that low vitamin D causes worse infections. Second, the study was done at one hospital, so the results might not apply to all populations or geographic areas. Third, the researchers didn’t follow patients over time to see if raising vitamin D levels actually improved their infections. Finally, the study didn’t account for all possible factors that could affect both vitamin D levels and infection severity, such as sun exposure, diet, or how long patients had diabetes.

The Bottom Line

Based on this research, doctors might consider checking vitamin D levels in patients with diabetic foot infections as part of their evaluation. If vitamin D is low, supplementation might be worth considering, though more research is needed to confirm it improves outcomes. This should be done alongside standard infection treatment, not instead of it. Confidence level: Moderate—this is promising evidence, but we need more studies to be certain.

This research is most relevant to people with diabetes who develop foot infections, their doctors, and healthcare providers treating diabetic complications. It’s also important for people with diabetes in general, as maintaining good vitamin D levels might help prevent infections. This doesn’t apply to people without diabetes or foot infections, though the findings might have broader implications for other types of infections.

If vitamin D supplementation does help, it would likely take several weeks to months to see improvements in infection healing, since vitamin D works by gradually improving immune function. Don’t expect immediate results—this would be a long-term supportive treatment alongside standard antibiotics and wound care.

Want to Apply This Research?

  • Track your vitamin D supplementation (if prescribed) and note any changes in wound healing progress, infection symptoms, or inflammation markers at weekly intervals. Record the date, dose taken, and observations about wound appearance, drainage, or pain levels.
  • If you have diabetes and a foot infection, ask your doctor to check your vitamin D level as part of your care plan. If it’s low, discuss vitamin D supplementation options. Also track sun exposure and vitamin D-rich foods (fatty fish, fortified milk, egg yolks) in your diet.
  • Set monthly reminders to review your vitamin D levels with your healthcare provider if supplementing. Track infection healing progress through photos of the wound (if safe to do) and note any changes in pain, swelling, or drainage. Monitor overall blood sugar control, as this affects infection risk too.

This research suggests an association between vitamin D levels and diabetic foot infection severity, but does not prove that vitamin D deficiency causes worse infections. This information is for educational purposes and should not replace professional medical advice. If you have diabetes and develop a foot infection, seek immediate medical attention from a healthcare provider. Do not start vitamin D supplementation without consulting your doctor, as it may interact with other medications or conditions. Always follow your doctor’s treatment plan for diabetic foot infections, which typically includes antibiotics, wound care, and other standard treatments.