A Randomized, Controlled Trial to Assess the Effect of Topical Insulin Versus Normal Saline in Pressure Ulcer Healing

Insulin has been used in wound healing to increase wound collagen, granulation tissue, wound tensile strength, and local production of insulin-like growth factors by fibroblasts. Saline is a widely used irrigating and wound dressing solution. Patients admitted to an acute care facility who had a Grade 2 or Grade 3 pressure ulcer were recruited to participate in a randomized, controlled trial to compare the effect of normal saline-impregnated gauze and insulin dressing in pressure ulcer healing. Persons with immunodeficiency, diabetes mellitus, pregnancy, osteomyelitis, and peripheral vascular illness were not eligible for the study. Study participants were randomized to receive either normal saline dressing gauze or insulin dressing twice daily for 7 days. At baseline, patient demographic data and ulcer history were recorded. Baseline and follow-up ulcer assessments (days 4 and day 7) included ulcer measurement (length and width) and completion of the Pressure Ulcer Scale for Healing (PUSH version 3.0) tool. Patients in the control group received dressings of sterile gauze soaked with normal saline; patients in the intervention group received topical insulin (1 U/cm2 wound area). The insulin was sprayed over the wound surface with an insulin syringe, allowed to dry for 15 minutes, and then covered with sterile gauze. To ascertain the safety of study participants, blood glucose levels were measured with a glucometer 10 minutes before and 1 hour after the topical insulin application in the intervention group. Treatment efficacy was deter- mined by assessing the reduction in wound area and PUSH scores at follow-up. Statistical analysis was performed; data are expressed as mean ± SD and percentage for continuous and categorical variables respectively. The differences in PUSH score and ulcer sizes between the 2 groups were analyzed using independent t-test, and within-group differences were analyzed using ANOVA with repeated measures; Greenhouse-Geisser correction was applied for the 3 consecutive measurements (day 1, day 4 and day 7). Fifty (50) patients (40 men, 10 women), ages 42.46 ± 15.47 years, with 50 ulcers, 25 in each treatment group, were enrolled. At baseline, demographic variables and wound characteristics were comparable between the 2 groups. By day 7, mean wound area had decreased from 11.79 ± 8.97 cm2 (day 1) to 11.43 ± 9.06 cm2 in the saline group (P = 0.566) and from 9.61 ± 6.39 cm2 (day 1) to 6.24 ± 4.33 cm2 (P less than 0.01) in the insulin group. Mean PUSH scores decreased from 10.52 ± 2.37 at baseline to 10.36 ± 2.40 on day 7 in the saline group (P = 0.475), and from 10.28 ± 1.10 to 8.52 ± 1.58 on day 7 (P less than 0.01) in the insulin group. No significant decrease in blood glucose level before and after insulin application (P greater than 0.05) was observed. Treatment with topical insulin was found be safe and effective in reducing pressure ulcer size as compared to normal saline-soaked gauze. Future studies utilizing larger sample sizes, longer follow-up times, and different types of chronic wounds and control treatments are warranted.