Diabetic nephropathy tends to develop more readily in patients with a family history of hypertension and/or disturbances in sodium transport across the plasma membrane. This prompted us to study the renal effects of diabetes mellitus in a rat strain which is predisposed to develop salt-sensitive hypertension, the Dahl salt-sensitive rat. Diabetes is associated with several aberrations in the renal handling of sodium, such as elevation of tubular Na⁺, K⁺ATPase activity. This effect was more pronounced in Dahl salt-sensitive than in Dahl salt-resistant rats. Severe renal lesions, characteristic of the advanced phase of diabetic nephropathy are very rarely observed in rats with streptozotocin diabetes. However, 2 months after induction of diabetes, the Dahl salt-sensitive rats had morphological signs of advanced glomerular disease. The urinary albumin concentration was very high, but did not correlate with the blood pressure. Non-diabetic Dahl salt-sensitive rats as well as Dahl salt-resistant diabetic and non-diabetic rats had little or no signs of glomerular disease and consistently very low urinary albumin concentrations. [Diabetologia (1997) 40: 367–373]