REN and diabetic kidney disease: In an open-label, prospective, randomized trial to evaluate the renoprotective effect of pentoxifylline on top of renin–angiotensin system inhibitors in patients with diabetic nephropathy (mean eGFR 37.4 mL/min/1.73 m2; median 24 h urine albumin 1100 mg), the patients were administered 1200 mg/day of pentoxifylline for 2 years.