Aim: To determine whether treatment with the stem cell stimulator Olimpiq® Stem×Cell prevents increase of retinal and renal vascular permeability in alloxan-induced diabetic rats. Materials and Methods: Two groups of Wistar rats were made diabetic by single intraperitoneal injection of Alloxan. The third, the control group, received vehicle alone. One diabetic group received Olimpiq® Stem×Cell treatment for 4 weeks. The permeability of the blood–retinal barrier (BRB) and renal vessels were measured by the extravasation of fluorescein–labeled bovine serum albumin. Results: Six weeks subsequently to Alloxan injection, significantly elevated the tissue fluorescence, the renal vascular leakage and BRB breakdown was demonstrated in the diabetic group, compared to the nondiabetic group. Olimpiq® Stem×Cell treatment significantly reduced the BRB breakdown, tissue fluorescence, and vascular leakage. Conclusion: Olimpiq® Stem×Cell would be a useful choice of treatment for complications associated with increased vascular permeability of diabetes, such as retinopathy or nephropathy.