Recent study has demonstrated that the long-acting somatostatin analogue administration effectively prevented initial renal growth in diabetic and uninephrectomized rats. In the present study we examined long-term effect of somatostatin analogue (Sandostatin) on renal enlargement in uninephrectomized-diabetic rat5. Animals were divided into 4 groups: (1) normal control rats (C) (n = 7), (2) uninephrectomized rats (NPX) (n = 7), (3) uninephrectomized-diabetic rats (NPX + DM) (n = 7) and (4) NPX + DM rats treated with Sandostatin (NPX + DM + Tx) (n = 9). All animals had free access to diet (50% protein) and water during the experimental period. To the NPX + DM + Tx rats, 2.5 micrograms of Sandostatin was given subcutaneously twice a day for 8 weeks. Periodic observations were done at 0, 4 and 8 weeks. After 8 weeks. NPX rats (0.540 +/- 0.017 (SEM)) had higher fractional kidney weights (FKW) (wet kidney wt/body wt) compared to C rats (0.410 +/- 0.014) (p < 0.0005), and both NPX + DM rats (0.983 +/- 0.098) and NPX + DM + Tx rats (1.091 +/- 0.042) had higher FKW compared to C rats (p < 0.0001) and NPX rats (p < 0.005), respectively. But no significant change of FKW was observed between NPX + DM rats and NPX + DM + Tx rats. Systolic blood pressure, BUN, serum creatinine, glomerular filtration rate and 24 hour urine protein excretion in NPX + DM rats were not different from those in NPX + DM + Tx rats.(ABSTRACT TRUNCATED AT 250 WORDS)