OBJECTIVE To investigate the relationship between serum cytokine levels and the infection severity and prognosis in patients with diabetic foot ulcer (DFU).

METHODS A total of 104 patients with DFU hospitalized in the Endocrinology Department of the Ninth Medical Center of Chinese PLA General Hospital from Jul. 2021 to Dec. 2023 were selected. Based on the classification criteria of the International Working Group on the Diabetic Foot (IWGDF/IDSA), patients were divided into the mild group (IWGDF/IDSA grade 2, 24 cases) and the moderate-to-severe group (IWGDF/IDSA grades 3-4, 80 cases) according to the infection severity. They were also divided into the minor amputation group (20 cases) and a non-minor amputation group (84 cases) based on whether they underwent minor amputation surgery. Baseline information and levels of interleukin (IL)-6 and other cytokines of each group were compared between the groups. Logistic regression analysis was used to assess the relationship between IL-6, high-sensitivity C-reactive protein (hs-CRP), white blood cell levels and the infection severity as well as minor amputation.

RESULTS In the moderate-to-severe infection group, 76.25% (61 cases) of patients had elevated serum IL-6 levels, which was higher than the 54.17% (13 cases) in the mild group, with a statistically significant difference (P < 0.05). There were no statistically significant differences in the levels of other cytokines. The hs-CRP and white blood cell levels of patients were higher in the moderate-to-severe infection group than in the mild infection group (both P < 0.05). After adjusting for multiple confounding factors by logistic regression analysis, IL-6 remained the influencing factor for moderate-to-severe infection. For the increase of each unit in IL-6, the risk of moderate-to-severe infection increased 1.066 times (95%CI: 1.005-1.130, P=0.032). There were statistically significant differences in hs-CRP and white blood cell levels between the minor amputation group and the non-minor amputation group (both P < 0.05). Logistic regression analysis showed that hs-CRP, white blood cell levels and IL-6 were not influencing factors for minor amputation.

CONCLUSIONS IL-6 levels are closely related to the infection severity in patients with DFU and are an independent influencing factor for moderate-to-severe infection. Actively detecting IL-6 levels in patients with DFU in clinical practice can help provide patients with timely and standardized antimicrobial therapy.