Reduced Progression of Diabetic Retinopathy After Islet Cell Transplantation Compared With Intensive Medical Therapy

BACKGROUND: Diabetic retinopathy is a major complication of type 1 diabetes and remains a leading cause of visual loss. There have been no comparisons of the effectiveness of intensive medical therapy and islet cell transplantation on preventing progression of diabetic retinopathy. METHODS: The British Columbia islet transplant program is conducting a prospective, crossover study comparing medical therapy and islet cell transplantation on the progression of diabetic retinopathy. Progression was defined as the need for laser treatment or a one step worsening along the international disease severity scale. An interim data analysis was performed after a mean 36-month follow-up postislet transplantation and these results are presented. RESULTS: The medical and postislet transplant groups were similar at baseline. Subjects after islet transplantation had better glucose control than the medically treated subjects (mean HbA1c 6.7%+/-0.9% vs. 7.5+/-1.2, P<0.01) and were C-peptide positive. Progression occurred significantly more often in all subjects in the medical group (10/82 eyes, 12.2%) than after islet transplantation (0/51 eyes, 0%) (P<0.01). Considering only subjects who have received transplants, progression occurred in 6/51 eyes while on medical treatment and 0/51 posttransplant (P<0.02). CONCLUSIONS: Progression of diabetic retinopathy was more likely to occur during medical therapy than after islet cell transplantation.