Effects of local infiltration of insulin around titanium implants in diabetic rats

In patients with type 2 diabetes mellitus (DM) there is poorer quality osseointegration than in other patients, and the success of oral implants is less. The aim of the present study was to investigate the influence of local infiltration of insulin at the implant–bone interface after implantation in diabetic rats. We used GK rats (8-week-old Goto-Kakizaki Wistar rats, n = 20) in a newly established model of type 2 DM, and Sprague–Dawley rats were used as controls (n = 10). GK rats were divided into two groups: those with DM alone and those with DM given insulin (INS) (n = 10 in each group). The INS group was given controlled-release insulin at the implant–bone interface. Rats were killed at 2 and 6 weeks after implantation. We evaluated bone–implant contact and bony volume in all rats. Implant–bone contact, osteoid and osteogenic volume, and the amount of newly formed bone in the DM group were significantly less than in the control (p < 0.05) and INS (p < 0.01) groups. Implant–bone contact in the INS group was less than that in the control group, but the amount of newly formed bone was greater. In conclusion, we suggest that although the implant–bone contact in the INS group did not reach the control level, direct infiltration of insulin could improve implant–bone contact. Local infiltration of insulin at the implant–bone interface may have important clinical implications by naturally improving the success of oral implantation in diabetic rats.