This prospective analytical study was conducted in Department of General Surgery, Shri BM Patil Medical College Hospital and Research Centre, Vijayapura, Karnataka, India. Study period was of 12 months, from January 2019 to December 2019. Institutional Ethical Committee Clearance (ethical clearance number BLDE(DU)/IEC/309/2018-19) was taken for the study. Procedure was explained and a written informed consent was taken from patients, prior to participation. Sample size was calculated with anticipated mean difference of mean at end point between the study groups as 2.1 and standard deviation as 2.0. A total of 76 patients were taken for study, 10 patients lost for follow-up and another six patients did not gave consent. Hence, a total of 60 patients were allocated into two groups, 30 each in topical insulin and normal saline based on the comparative method, alternately, patients were divided into two groups.

Group A- Patients underwent dressing with topical insulin,

Group B- Patients underwent dressing with normal saline.

All diabetic patients between the age group of 25 to 70 years, presenting for the first time with ulcers measuring more than one cm below ankle in dorsum of foot and blood glucose levels between 110 and 130 gm/dL were included in the study. Patients who have been operated for diabetic foot infections earlier (in the same foot), uncontrolled diabetes with HbA1c levels >8, patients with absent peripheral pulses in dorsalis pedis artery, posterior tibial artery, anterior tibial artery and who were not on regular follow-up were excluded from the study.

On admission detail history, clinical examination was done. Laboratory investigations such as Complete Blood Count (CBC), Fasting Blood Sugar (FBS), Post Prandial Blood Sugar (PPBS), Liver Function Test (LFT), Renal Function Test (RFT) blood group RH typing, Renovascular Disease (RVD), Hepatitis B surface Antigen (HBsAg). All other tests that were done were all comparable in both groups they did not affect much on the treatment strategy so they have not been highlighted, only the tests which are directly related to study have been mentioned. Anaesthetic fitness was taken. Surgical debridement of the patients were done and a sterile transparent gauze was placed on the wound and wound borders were marked. With the help of ruler the two largest perpendicular diameters were measured and wound area was calculated by multiplying these two diameters and area of ulcer was determined. Patients were alternately divided into two groups. Ulcers were cleaned with normal saline and a sterile gauze soaked with Human mixtard insulin and normal saline (4 units 0.1 mL-Human mixtard insulin in 1 mL normal saline for each 10 cm² of wound) was applied once daily, in group A. In group B, ulcers were cleaned with normal saline and covered with sterile gauzes. All patients were treated empirically with Inj. Amoxycillin-clavulanic acid and Inj. Metronidazole. Later antibiotics were changed according to pus culture and sensitivity reports. Daily dressing was done. Ulcer area was measured on day 1, day 7 and day 15. Reduction in the area of ulcer area was calculated at day 7 and day 15 in comparison with day 1 area of ulcer.

Data was tabulated and the two groups were compared with reference to area and percentage of reduction. Study data was analysed using SPSS software and Microsoft excel software. Association of two qualitative variables was done by Chi-square test. A p-value of <0.05 was considered as statistically significant.

Total 60 patients were included for study and alternatively divided in two groups. Group A patients underwent dressing with topical insulin while group B patients underwent dressing with normal saline. Mean age distribution was 51.2±9.6 years and 50.6±10.9 years in group A and B, respectively. Mean HbA1c at admission was 6.3±0.9 and 6.1±0.8 in group A and B, respectively. Difference between group A and group B was statistically not significant [Table/Fig-1]. On day 0, 7, 15 wound measurements were done. A statistically significant difference was noted in reduction of average surface area of wound at day 7, 15 between group A and B. Insulin dressing group shown better changes than saline dressing group. Percentage reduction in average surface area of wound at day 15 was 67.8±11.45 in insulin dressing group and 49.51±18.21 in saline dressing group, statistically significant difference was noted. Average time required for granulation tissue to appear was 6.08±2.15 days and 9.48±4.21 days in group A and B respectively, statistically significant difference was noted (p<0.001) [Table/Fig-2].

Based on the 2015 prevalence data from the International Diabetes Federation, it is estimated that foot ulcers develop in 9.1 million to 26.1 million people with diabetes annually worldwide [9]. A systematic review and meta-analysis of the global prevalence of diabetic foot ulcers showed that the global prevalence of diabetic foot ulcers was 6.3%, higher in males than in females, and higher in type 2 than in type 1 diabetic patients [10]. Diabetic foot ulcers respond poorly to conventional dressings and thus these patients are over-burdened with prolonged hospital stay and increased financial overload. A normal working man loses his quality working days and this becomes a major economic crisis to the concerned family. There is defective wound healing in diabetes due to decreased manufacture of growth factors, poor angiogenic response, macrophage function, collagen accumulation, epidermal barrier function and keratinocyte and fibroblast proliferation and migration [11-14]. Insulin acts as a growth factor, in several preclinical studies insulin proved to stimulate angiogenesis, collagen formation, matrix formation and granulation tissue proliferation. Insulin stimulates the growth and development of different cell types and affects proliferation, migration and secretion by keratinocytes, endothelial cells and fibroblasts [15]. Topical application of insulin in diabetic patients with ulcers has a significant improvement in healing of the ulcer.

In present study majority of the patients were male (36, 60%) than female (24, 40%). Jyothylekshmy V et al., had 200 (72.2%) males and 77 (27.7%) females in their study [16]. The age range in present study was between 25 and 70 and the mean age was found to be 51.2±9.6 years and 50.6±10.9 years in group A and B, respectively. Mean reduction in average surface area of wound at day 15 was 67.8±11.45 in insulin dressing group and 49.51±18.21 in saline dressing group, statistically significant difference was noted. Average time required for granulation tissue to appear was 6.08±2.15 days and 9.48±4.21 days in group A and B, respectively, statistically significant difference was noted (p<0.001). Similar findings were noted by Pandey S et al., Prasad A et al., and Mahidhar RV et al., [17-19]. Significantly increased proliferation of granulation tissue was noticed in most of the patients who received local insulin therapy and improvement of the wound in the form of diameter and depth in insulin group.

The present study was of a small sample size, limited duration of follow-up and patients with controlled diabetes. Further research is needed with large sample size and longer follow-up, in patients with fasting sugar values more than 180 mg/dL. Also other insulin preparations can be tried with ethical permission.

The use of topical insulin is safe and effective in patients with diabetic foot ulcers. Topical insulin in diabetic foot ulcers has a significant improvement in ulcer healing as evident by significant reduction in ulcer area. Further large scale studies are needed to document role of insulin in the healing of diabetic foot ulcers.