Effect of local insulin injection on wound vascularization in patients with diabetic foot ulcer

The aim of the present study was to investigate the effect of local insulin injection on granulation tissue formation in the wounds of patients with diabetic foot ulcer. Thirty-two patients with diabetic foot ulcer were randomly divided into an insulin (n=18) and a control (n=14) group. In the diabetic foot ulcer wound, the insulin group were administered insulin and the control group were administered an equal volume of saline. Prior to injection and at 0.5, 1.0, 2.0 and 4.0 h after injection, the fingertip blood glucose levels were determined. The growth of granulation tissue was assessed continuously for 12 days. Wound tissue was harvested at 0, 5, 7 and 12 days for the detection of CD34 expression by immunohistochemistry. The microvessel density (MVD) was calculated. No significant difference in the fasting blood glucose level was found between the two groups at any time-point (P>0.05). Growth of granulation tissue in the insulin group was more marked from 7 days after local insulin injection (24.87±0.24) and was significantly different from that in the control group (18.66±0.45) (P<0.01). New vessels were observed in the insulin group 3 days after insulin injection; however, there was no significant difference in MVD compared with the control group (P>0.05). The MVD in the insulin group increased markedly from 5 days after treatment, and the difference between the two groups was significant (P<0.01). In conclusion, local injection of insulin into the base of a diabetic foot ulcer has a significant effect on systemic blood glucose and may promote wound healing by improving the growth of granulation tissue.