Thirty-two male Wistar rats were used to verify the effects of chronic noni juice administration on blood glucose levels and its relation to physical performance. In half of the rats, diabetes mellitus (DM) was induced with STZ, and the rats were submitted to an incremental workload running test (IWT) until fatigued so that oxygen consumption and performance indexes (exercise time to fatigue and workload) could be analyzed before noni administration. Then, the control and DM groups received a placebo (saline solution) or noni juice (dilution 2:1) at a dose of 2 mL/kg once a day for 60 days. The result was four groups: control + placebo (CP), control + noni (CN), DM + placebo (DMP), and DM + noni (DMN). All groups were then given a third IWT to verify the effect of the noni juice on exercise performance and glycemia. Twenty-four hours after the third test, all animals were euthanized and blood and kidneys were removed for posterior analysis. Noni administration improved the time to fatigue and workload in DM rats by reducing hyperglycemia. These results could be associated with an improved energy e ciency promoted by noni ingestion. However, our results provided evidence that chronic noni administration causes kidney damage since elevated glomerular ltration was observed at the same magnitude as the non-treated DM group. In conclusion, chronic noni ingestion promoted glycemic control and improved the performance in DM rats but caused kidney toxicity.