Can a blood test predict major limb events for diabetic foot ulcers?
For people with diabetic foot ulcers, a simple blood test measuring the C-reactive protein-to-albumin ratio (CAR) may help predict the risk of major limb events like amputation or unplanned surgery. A 2025 study found that higher CAR levels were independently linked to a greater chance of these events within 6 months 4. This test reflects both inflammation and nutritional status, which are key factors in wound healing.
What the research says
A retrospective cohort study of 139 hospitalized diabetic foot ulcer patients found that 31% experienced a major adverse limb event (MALE) within 6 months 4. MALE included major amputation, unplanned limb revascularization, or death related to foot deterioration. The study identified the C-reactive protein-to-albumin ratio (CAR) as an independent predictor: for each unit increase in CAR, the odds of a MALE rose by 22% (adjusted odds ratio 1.22, 95% CI 1.03–1.48) 4. Another independent predictor was larger ulcer area 4. The researchers combined these factors into a nomogram (a prediction tool) that showed good accuracy in identifying high-risk patients 4. While other studies have looked at different blood markers for diabetic foot ulcers, such as platelet count and lymphocyte count for diagnosing severe ulcers 5, or antifungal resistance patterns 3, the CAR specifically stands out as a blood test that can predict future limb-threatening events. It is important to note that this is from a single study, and more research is needed to confirm these findings in broader populations.
What to ask your doctor
- Should I have my C-reactive protein and albumin levels checked to calculate my CAR?
- What does my CAR result mean for my risk of amputation or other major limb events?
- How does my ulcer size and other factors combine with blood test results to guide my treatment plan?
- Are there other blood tests or imaging studies that could help predict my healing and risk of complications?
- If my CAR is high, what additional steps can we take to reduce my risk?
This question is drawn from common patient questions about this topic and answered using cited medical research. We do not provide individualized advice.