Tofogliflozin, a SGLT2 inhibitor, improves diabetic ocular complications in Spontaneously Diabetic Torii rats

To evaluate the effect of tofogliflozin on diabetic complications in Spontaneously Diabetic Torii (SDT) rats. Methods. The rats were classified as untreated SDT rats, tofogliflozin-treated SDT rats, and normal Sprague-Dawley (SD) rats. We evaluated the urinary albumin (24 hours), crystalline lens opacity (cataract), and diabetic retinopathy (DR) 20 and 40 weeks after diabetes onset. Cataracts were classified as minimal, moderate, or severe. The retinal thickness 500 m from the optic nerve disc was measured to evaluate the DR. Results. The urinary albumin was significantly (p<0.05) higher in untreated SDT rats than treated SDT rats and normal rats at 20 weeks: untreated eyes, 48.5 (range, 18.2-79.2); treated eyes, 13.4 (range, 7.2-15.8); and normal eyes, 0.4 (range, 0.2-0.5). Severe cataracts developed in all untreated SDT rats; minimal or no crystalline lens opacity developed in all normal rats. Severe cataracts developed significantly less in treated SDT rats than in untreated SDT rats at 20 and 40 weeks. Severe opacities developed in all untreated eyes at 20 and 40 weeks (p<0.01). Minimal opacities developed in all normal eyes (p<0.01). Severe opacities did not develop in any treated eyes at 20 and 40 weeks (p<0.01, p<0.05, respectively); moderate opacities developed in three eyes at 20 weeks (p<0.05) and four eyes at 40 weeks (p<0.01). The retinas in untreated SDT rats were significantly thicker than in normal rats at 20 and 40 weeks. The retinas in treated SDT rats were significantly (p<0.05) thinner than in untreated SDT rats at 20 weeks: untreated eyes, 157.5 microns (range, 128-190); treated eyes, 138.5 microns (range, 107-157); and normal eyes, 119 microns (range, 76.2-131). Significant differences in the retinal thicknesses were not seen at 40 weeks. Conclusion. Tofogliflozin might have an effect on diabetic complications in SDT rats.