Weakness of anastomotic site in diabetic rats is caused by changes in the integrity of newly formed collagen.

Aims: Diabetes mellitus often causes anastomotic leakage leading to severe complications after surgery. The purpose of this study was to determine whether collagen synthesis is correlated with the anastomotic strength in diabetic animals in special reference to collagen type differences.

Methods: Thirty Lewis rats weighing approximately 250 g were made diabetic by tail vein injection of streptozotocin (STZ). Laparotomy was performed through a midline incision under ether anesthesia. A colonic segment 5 cm distal to the ileocecal junction was transected then anastomosed with absorbable suture. Anastomotic strength was measured on days 3, 5, 7 and 14 postoperatively, and compared with normal rats. Collagen type I and type III mRNA together with the total collagen concentration were measured in anastomotic sites.

Results: Anastomotic strength in diabetic rats was significantly lower on day 7, but gradually recovered up to day 14. There was no statistical significance between the two groups in hydroxyproline concentrations. Although the expressions of mRNA of collagen type III in both groups were statistically not different, that of collagen type I in the diabetes group merely increased and was clearly less than that of the control group.

Conclusions: Anastomotic integrity in diabetic rats was significantly damaged on day 7 after surgery but recovered by day 14. This is caused not by the total contents of collagen accumulation but by the decrease of newly formed collagen type I contents.