Is increased colon subepithelial collagen layer thickness in diabetic patients related to collagenous colitis? An immunohistochemical study

In this study, we evaluated immunohistochemically whether increased thickness of the colon subepithelial collagen layer in diabetic patients relates to collagenous colitis.A total of 100 patients (25 in each group) were included in this study. There were diabetic patients with chronic diarrhea in the first group, diabetic patients without chronic diarrhea in the second group, non-diabetic patients with chronic diarrhea in the third group, and control patients in the fourth group. The endoscopic biopsy specimens were obtained from the rectum, sigmoid colon, and descending colon. The thickness of the subepithelial collagen layer was measured using the ocular micrometer method. The immunohistochemical staining was performed with type 1 collagen and fibronectin antibody.The thickness of the colon subepithelial collagen layer in diabetic patients with or without diarrhea was significantly greater than that in control patients. This thickened subepithelial collagen layer in diabetic patients was stained with fibronectin antibody, but not with type 1 collagen antibody in the immunohistochemical study. These immunohistochemical staining characteristics were not similar to those in collagenous colitis, but were similar to those in normal subjects.Increased colon subepithelial collagen layer thickness in diabetic patients does not relate to collagenous colitis.