In order to investigate the effects of Okchunsan (Sample A), Gamiokchunsan (Sample B) and Spinacia oleracea L. (semen: Sample C) on streptozotocin-induced diabetic rats, the experimal study was performed on the levels of glucose, insulin, total cholesterol, triglyceride, total protein, albumin, blood urea nitrogen (BUN), electrolytes $(Na^+,;Ka^+,;Cl^-)$, GOT and GPT in serum, hemoglobin, hematocrit, urine volume, glucose and protein in urine, body weight, liver and kidney weight. The results were obtained as follows: 1. Serum glucose levels were significantly decreased in Sample A. B and C group and serum insulin levels were increaseclin Sample A and B group. 2. Serum total cholesterol levels were recovered as the normal value in Sample A, B and C group and serum triglyceride levels were decreased in Sample A and C group. 3. Serum total protein levels were increased in Sample C group, BUN levels were decreased in Sample A and C group. 4. Serum $Na^+;and;Cl^-$ levels were increased, $K^+$ levels were decreased in Sample A, B and C group. 5. Serum GOT and GPT levels were remarkedly decreased in Sample A, B and C group. 6. Urine volume, urine glucose and protein levels were decreased in Sample A, B and C levles. 7. Body Weight showed a tendancy of increasing in Sample A, B and C group. 8. Levels of serum albumin, hemoglobin, nematocrit, liver and Kidney weight were not significantly changed. According to above results, Okchunsan, Gamiokchunsan and spinacia oleracea L. (Semen) were expected to be applied to the treatment of diabetes mellitus and its complications.