Post-transplant diabetes mellitus: risk factors, frequency of transplant rejections, and long-term prognosis.

BACKGROUND: Estimates of the incidence of new-onset diabetes after renal transplantation vary between 2% and 54%. It was the aim of the present trial to study the prevalence of post-transplant diabetes mellitus (DM), the risk factors, the frequency of transplant rejections, and the long-term prognosis.
METHODS: We studied all consecutive patients with endstage renal disease, but without DM who received kidney transplantation at our center since 1992 (n = 253; age, 52.2 +/- 12.6 years; body mass index, 22.0 +/- 7.9 kg/m2). Follow up was 3.3 +/- 1.6 years (range, 0.1-17.7) years.
RESULTS: In total, 43/253 patients (17%) developed new-onset DM after transplantation. Patients with new-onset diabetes were significantly older (58.3 +/- 11.4 vs 50.9 +/- 12.5 years; P < 0.01) and had a tendency to a higher body mass index (24.0 +/- 8.5 vs 21.6 +/- 7.8 kg/m2; P = 0.077). There were no differences between the groups in respect of blood pressure control (137.7 +/- 19.0/81.8 +/- 14.2 vs 137.1 +/- 21.9/83.9 +/- 13.1 mmHg; P = 0.89/0.39), glomerular filtration rate (58.0 +/- 28.1 vs 64.1 +/- 22.1 ml/min per 1.73 m2; P = 0.13), steroid dosage (4.5 +/- 1.2 [n = 21] vs 4.6 +/- 2.2 [n = 135] mg/day; P = 0.13), or the frequency and dosage of immunosuppressive drugs such as cyclosporine, tacrolimus, and sirolimus during the follow up. However, more patients with post-transplant diabetes received steroids (83.7% vs 64.3%; P = 0.021) and azathioprine (41.9% vs 24.3%; P = 0.030). Patients with new-onset diabetes had higher serum creatinine values (163.4 +/- 67.9 vs 138.7 +/- 59.5 micromol/l; P = 0.017). The mean hemoglobin (Hb)A1c in patients with DM was 6.28 +/- 1.29% (Tosho HPLC; mean normal, 5.15%). In 18 patients (7.1%) transplant rejections occurred (16 patients without DM [7.6%] vs 2 patients with new-onset DM [4.7%]; P = 0.39). On performing multivariate analysis, the only parameter found to be associated with new-onset DM was the body mass index (R2 = 0.05; beta = 0.23; P = 0.02), and the only factor associated with transplant rejection was fasting blood glucose (R2 = 0.07; beta = 0.28; P = 0.02). None of the other parameters included in the models (age, duration after transplantation, diabetes duration, immunosuppressive therapy, HbA1c, HLA mismatches) showed any associations.
CONCLUSIONS: The prevalence of new-onset DM after renal transplantation was 17%. The most important parameter associated with new-onset diabetes was a higher body mass index, and the most important parameter associated with transplant rejection was an elevated fasting blood glucose level. To prevent transplant rejections and to improve patients' outcome, in addition to providing optimal immunosuppressive therapy and HLA matching, good blood pressure control and HbA1c, but also near normal fasting blood glucose levels, should be achieved.