Expression of glucose transporters in duodenal mucosa of patients with type 1 diabetes

Aims A higherSGLT1andGLUT2gene expression was shown in the intestine of subjects with type 2 diabetes, while no data have been reported in type 1 diabetes (T1D). The purpose of our study was to evaluate the expression of glucose transporters in duodenal mucosa of subjects with T1D, compared to healthy controls (CTRL) and to patients with celiac disease (CD), as gut inflammatory disease control group. Materials and methods Gene expression ofGLUT1,GLUT2,SGLT1andSGLT2was quantified on duodenal mucosa biopsies of subjects with T1D (n = 19), CD (n = 16), T1D and CD (n = 6) and CTRL (n = 12), recruited at San Raffaele Hospital (Milan, Italy), between 2009 and 2018.SGLT2expression was further evaluated by immunohistochemical and immunofluorescence staining. Results The expression of all four glucose transporters was detected in duodenal mucosa of all groups. A reducedGLUT2,SGLT1andSGLT2expression was observed in CD in comparison with T1D and CTRL, as expected;GLUT1was significantly more expressed in T1D compared to CTRL.SGLT2expression was quantified at much lower levels than other transporters, with no differences between groups.SGLT2expression was confirmed by immunohistochemistry in a restricted number of enterocytes lining in the mucosa of intestinal villi, also shown on immunofluorescence. Conclusions Our results show that glucose transporters expression in duodenal mucosa of subjects with T1D, except an increasedGLUT1, is not different from that observed in healthy controls. The expression ofSGLT2in human duodenal mucosa, although at low intensity, represents a novel finding.