The purpose of the study was to investigate the effects of daily oral feeding Momordica charantia (MC) (200 mg/kg), Eugenia jambolana (EJ) (200 mg/kg), Mucuna pruriens (MP) (200 mg/kg) and Tinospora cordifolia (TC) extracts for 40 days on blood glucose concentrations and kidney functions in streptozotocin (STZ)-diabetic rats. Plasma glucose levels, body weight, urine volume and urinary albumin levels were monitored on every 10th day over a 40-day period while plasma creatinine levels were assessed at the beginning and end of experiment. Renal hypertrophy was assessed as the ratio between the kidney weight and total body weight. Plasma glucose concentrations in STZ-diabetic mice were reduced by the administration of extracts of MC, EJ, TC and NIP by 24.4, 20.84, 7.45 and 9.07%, respectively (P < 0.005 for MC, EJ, NIP and P < 0.05 for TC). Urine volume was significantly higher (P < 0.005) in diabetic controls and NIC, EJ, NIP and TC treatment prevented polyuria (P < 0.001, 0.0001, 0.01 and 0.001, respectively). After 10 days of STZ administration urinary albumin levels (UAE) were over 6 fold higher in diabetic controls as compared to normal controls. Treatment with NIC, EJ, NIP and TC significantly prevented the rise in UAE levels from day 0 to 40 in comparison to diabetic controls (P < 0.0001, 0.0001, 0.05, 0.05, respectively). Renal hypertrophy was significantly higher in diabetic controls as compared to non-diabetic controls. NIC and EJ partially but significantly (P < 0.05) prevented renal hypertrophy as compared to diabetic controls. TC and NIP failed to modify renal hypertrophy. Results indicate that these plant drugs should be studied further. <(c)> 2001 Elsevier Science Ireland Ltd. All rights reserved.