We read with great interest the article by Voytovich et al. [1], demonstrating the beneficial effect of a new insulin sensitizer, rosiglitazone, in renal transplant recipients. They concluded that short-term treatment with rosiglitazone improves glucose tolerance, insulin sensitivity and endothelial function in this group of patients.
The treatment modalities for diabetes mellitus and glucose intolerance include lifestyle modification, diet, exercise and pharmacologic intervention [2]. In this study, the authors did not give any information on dietary intervention, which is the mean predictor of the blood glucose level in diabetic and glucose-intolerant patients. Although this was not a crossover study, as the authors reported in the limitations section of the study, it might have been better to give a 4 week study period with a standard diet for all patients, in order to exclude the effect of nutritional factors. Also, seven patients were determined as post-transplant diabetes mellitus (PTDM) according to oral glucose tolerance test (two of them were previously known PTDM), but the authors did not give any information on the patients' glycohaemoglobin or fructosamine levels, which could be more valuable parameters (not influenced by acute changes in blood glucose) before and after the rosiglitazone, even in a 4 week period. Fructosamine seems to be a more suitable measure in this study design, because it is a more sensitive marker for abnormal glucose tolerance and it reflects 34 weeks' blood glucose control [3].
The main immunosuppressive agents responsible for PTDM are calcineurin inhibitors and steroids. Current evidence shows greater diabetogenity of tacrolimus in multicentre studies [4]. Therefore, it would be interesting to see if there is any correlation in insulin resistance and the response to the rosiglitazone between the patients on cyclosporin or tacrolimus.
Conflict of interest statement. None declared.
Ankara University School of Medicine Department of Nephrology Ibni Sina Hospital Ankara, Turkey Email: iergun{at}medicine.ankara.edu.tr
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