Introduction: The purpose of this study was to examine the effects of four weeks follow-up of 10 week aerobic exercise training on blood apelin concentration and its role in pain threshold in type 1 diabetic (T1DM) rats.                                                                                                                       
Methods: 24 male Wistar rats were randomly divided into healthy and diabetic groups. Diabetes was induced in the diabetic groups by a single subcutaneous injection of streptozotocin (50 mg/kg). Then, each group (healthy and diabetic) was divided into two subgroups of experimental (training group) and control (no training) groups. The aerobic training in the experimental group consisted of treadmill running, 5 days a week, 60 min/day for 10 weeks followed by a 4-weeks detraining period. We used tail-flick to assess the thermal pain threshold and an apelin C-Terminus enzyme immunoassay kit to assess plasma apelin levels. The plasma apelin levels and pain threshold data were analyzed using repeated measures analysis of variance (ANOVA) and Independent-Sample T test. Level of significance was set at p<0.05.                      
Results: It was found that a period of aerobic training, in both healthy and diabetic rats, could significantly reduce plasma apelin level and increase pain threshold. The changes returned to normal after a period of detraining.
Conclusions: It can be concluded that 4-weeks detraining can affect plasma apelin levels and pain threshold in type1 diabetes