Early alteration of kidney function in nonuremic type 1 diabetic islet transplant recipients under tacrolimus-mycophenolate therapy

Background. Transplant patients on tacrolimus therapy exhibit a reduced glomerular filtration rate (GFR). The type of graft and immune treatment protocol may influence the extent and reversibility of this side effect. Methods. The present single-center study is conducted in 48 nonuremic type 1 diabetic recipients of an intraportal islet-cell graft under maintenance immunosuppression (IS) with tacrolimus and mycophenolate mofetil. Estimated GFR (eGFR) and albuminuria were followed up to 5 years posttransplantation. Results. Mean eGFR values decreased by 19 mL/min/1.73 m² after 1 to 2 weeks of IS (P<0.0001) and then remained stable throughout the complete treatment period. The decrease was related to predose trough tacrolimus concentrations or doses and disappeared upon its discontinuation; it was also associated with the presence of albuminuria at the time of transplantation. Tacrolimus treatment resulted in a reduction of albuminuria; its discontinuation restored albuminuria to the initial levels. Conclusions. The use of tacrolimus in our islet-cell transplant protocol caused an initial 20% reduction in eGFR, which was reversible following its discontinuation, at least within the 5-year follow-up period. The associated reduction in albuminuria was also reversible, compatible with a tacrolimus-induced preglomerular vasoconstriction. These observations support further use of our tacrolimus regimen in this patient population.