Does renal function deteriorate more rapidly in diabetic cardiac transplant recipients?

Selection criteria for cardiac transplant candidates with diabetes mellitus (DM) have been liberalized resulting in increased numbers of diabetic patients receiving organs. Calcineurin inhibition results in nephrotoxicity. Whether this nephrotoxicity is accelerated in diabetic heart transplant recipients is unknown.

To investigate this question, we derived the glomerular filtration rate (GFR) at transplant and at multiple time intervals thereafter for adult heart transplants performed from January 1, 2000 to January 1, 2005. GFR was estimated using the Modification of Diet in Renal Disease Study equation (GFRMDRD) and the Cockcroft-Gault (GFRCG) formula.

In all, 257 patients were nondiabetic and 102 patients were diabetic before and after transplant. The diabetic patients were older (57+/-8 vs. 53+/-13 years; P<0.01) and had greater body mass index (27.5+/-5.1 vs. 25.5+/-4.4 kg/m; P<0.01) than nondiabetic patients. Baseline renal function was significantly reduced in diabetic patients with higher serum creatinine (1.6+/-0.5 vs. 1.4+/-0.5 mg/dL), lower GFRCG (65+/-27 vs. 73+/-35 mL/min), and lower GFRMDRD (54+/-23 vs. 65+/-32 mL/min; all P<0.01) than nondiabetic patients. All patients were treated with cyclosporine or tacrolimus posttransplant. The change in the GFRMDRD in nondiabetic and diabetic patients was constant and comparable at 1, 2, and 3 years posttransplant. In normal subjects, GFRMDRD declined from baseline by 7+/-26, 5+/-23, and 7+/-23 mL/min(2) and in the diabetic patients was 13+/-22, 9+/-26, 10+/-22 ml/min(2) at 1, 2, and 3 years, respectively (P=NS).

This data suggests that nephrotoxicity posttransplant is not accelerated in diabetic recipients.