Abstract Background and Aims Post-Transplant Diabetes Mellitus (PTDM) is a severe disease that may affect about 30% of renal transplant patients. PTDM beyond 12 months (late PTDM) mostly develops in subjects with prediabetes. Although exercise may have a potential role in preventing late PTDM, there is scarce evidence on the effect of exercise in renal transplantation. We designed a 12-month exploratory study to test the capacity of therapeutic exercise in reverting prediabetes to prevent the development of late-PTDM. Method This is a pilot study in which renal transplant patients with prediabetes were treated with exercise for 12 months. To detect prediabetes and to evaluate the reversibility, relapse, or persistence of prediabetes, the oral glucose tolerance test (OGTT) was performed at baseline and every 3 months to the end of the study. Prediabetes was defined by the presence of Impaired Fasting Glucose (IFG) in 100-125 mg/dl and/or Impaired Glucose Tolerance (IGT) between 140-199 mg/dL after the OGTT. The protocol included a stepped incremental plan of aerobic and/or strength training. The frequency, intensity, and duration of aerobic exercise, as well as the addition of strength training depended on the recovery, persistence, or recurrence of prediabetes. All patients started with moderate aerobic exercise (brisk walking), 30 min/day and 5 times per week and, based on that, changes in prescription were considered every 3 months. Additionally, we evaluated: (a) an active plan for promoting adherence to exercise (telephone calls, digital technology, and visits) and (b) improvements in metabolic risk factors: obesity, dyslipidaemia, and blood pressure. Since prediabetes may spontaneously revert to normal glucose metabolism in 25-30% [1], we assume that in 60 cases, the spontaneous reversibility could be of 30% (n = 18) and the reversibility induced by exercise may account for another 30% (n = 18), so the total reversibility will be 60%. Considering an expected drop out of 20%, the number of cases necessary to include was 72 patients. Results The study was early interrupted due to efficacy after the evaluation of 27 patients that reach 12 months of follow-up. Mean age was 54.2 ± 9.6 and 67% were men. Half of the patients were obese and most had overweight. At baseline IGT or IFG alone were found, respectively, in 13 (48%) and 5 (19%) patients, and the combination of both in 9 (33%). All patients were on prednisone and tacrolimus with the addition of mycophenolate on 20 subjects and 7 on everolimus. Of the group, 16 (60%) reverted to normal glucose levels (fasting and 120 min after an OGTT): this was two time higher than the 30% reversibility rate shown in a previous publication [1], p <0.05, assuming a potency of 85%. In parallel, 11 (40%) subjects had prediabetes (9) or developed PTDM (2). No significant changes were found in weight during follow-up in all groups whereas triglycerides diminished in patients on whom prediabetes reverted (154 mg/dL ± 61 to 96 ± 27; p = 0.016). At the end of follow up, adherence to exercise was good (≥70%) in 13 patients (∼50%), moderate (40-70%) in 9 (∼30%) and bad (≤40%) in 5 (∼20%). Finally, all patients with good adherence reverted to normoglycaemia, 3 out of 9 (33%) cases with moderate reverted to normal glucose metabolism and no cases with bad adherence improved on follow-up. No relevant injuries attributed to exercise were observed during the study. Conclusion Therapeutic exercise is safe and effective to improve glucose metabolism in renal transplant patients with prediabetes. Adherence is a crucial aspect to consider in the planification of exercise treatment.
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