Effect of weight loss using formula diet on renal function in obese patients with diabetic nephropathy

OBJECTIVE: To evaluate the effect and safety of treatment with low-calorie formula diet on renal function and proteinuria in obese patients with diabetic nephropathy. DESIGN: Prospective study on safety and efficacy of a 4-week low-calorie (11-19 kcal/kg/day) normal-protein (0.9-1.2 g/kg/day) diet partly supplemented with formula diet. SUBJECTS: In all, 22 obese patients with diabetic nephropathy (BMI: 30.4 +/- 5.3 kg/m(2), HbA1c: 7.1 +/- 1.4%, serum creatinine: 172.4 +/- 57.5 mmol/l, urinary protein: 3.3 +/- 2.6 g/day). RESULTS: The mean body weight decreased by 6.2 +/- 3.0 kg. The mean systolic blood pressure, creatinine, blood urea nitrogen, urinary protein, and 8-hydroxydeoxyguanosine decreased significantly by 7.5 +/- 12.7 mmHg, 41.6 +/- 23.9 mmol/l, 1.50 +/- 1.61 mmol/l, 1.8 +/- 1.7 g/day, and 3.1 +/- 3.6 ng/mg creatinine, respectively. No patient had increased serum creatinine and urinary protein. Mean creatinine clearance (40.6 +/- 17.9 to 46.1 +/- 14.6 ml/s/ 1.73 m(2)) and serum albumin showed no significant changes. Delta serum creatinine and Delta urinary protein correlated with Delta body weight (r 0.62 and 0.49, respectively) and Delta visceral fat area (r 0.58 and 0.58, respectively), but did not correlate with Delta systolic blood pressure, Delta fasting blood glucose and Delta subcutaneous fat area. CONCLUSION: These results suggested that weight reduction using formula diet might improve renal function and proteinuria safely for a short term in obese patients with diabetic nephropathy.