Associating Insulin Instillation with Negative Pressure Wound Therapy Reduces Insulin Resistance in Diabetic Patients with Infected Foot Wounds

In this work we investigated whether a joint treatment with insulin instillation and negative pressure wound therapy (NPWT) would reduce insulin resistance (IR) in diabetic patients with infected diabetic foot ulcers (DFUs) and improve their healing. We also studied the effects of insulin+NPWT treatment on the inflammatory response coupled with wound healing. Seventy-five diabetic patients with infected DFUs were recruited and randomly divided into equal (n=25) groups treated respectively with NPWT alone, NPWT+insulin, and conventional dressings (controls). Thereafter, the ulcers’ healing progress was assessed. The serum levels of Tumor Necrosis Factor-α (TNF-α), Interleukin-2 (IL-2), and Interleukin-6 (IL-6) were measured at 1 day before and at 7, 14, and 21 days after each treatment using specific double-antibody sandwich enzyme-linked immunosorbent assays (ELISA). Serum glucose was measured via a glucose-oxidase method, and serum insulin via radioimmunoassay. In each patient, IR was appraised via the Homeostasis Model Assessment (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI). Our results showed that at 7, 14 and 21 days post-treatment, with respect to the control group the two NPWT-treated groups had (i) significantly (p < 0.05) lower serum levels of TNF-α, IL-2 and IL-6; (ii) a significantly (p < 0.01) greater reduction in IR; and (iii) significantly (p < 0.05) higher wound healing rates. Moreover, at 14- and 21-days post-treatment, the NPWT+insulin-treated group had a significantly (p < 0.05) higher wound healing rate than the NPWT alone-treated group. In conclusion, the combined NPWT+insulin instillation treatment gave superior results by improving wound healing, decreasing inflammation at the wounds surface, and reducing IR in diabetic patients with infected DFUs.