The present study was carried out to investigate the effect of the anti-oxidant drug lipoic acid on the treatment of STZ- diabetic rats. The effect of different durations of treatment by lipoic acid on some biochemical parameters, pharmacology of urinary bladder & pathology of the kidney were studied. The results showed that there was a significant decrease in the levels of glucose, triglycerides, total cholesterol, creatinine and maondialdehyde in the treated diabetic rats by lipoic acid. The response of the bladder in the rats treated with lipoic acid was significantly different from that of untreated ones. It was also found that the treatment of diabetes by lipoic acid improves the histopathological changes in kidney tissues than untreated ones.