A Randomized Trial of Low-Protein Diet in Type 1 and in Type 2 Diabetes Mellitus Patients With Incipient and Overt Nephropathy

Centre d'Investigation Clinique, INSERM-APHM, Marseille, France.
Journal of Renal Nutrition (Impact Factor: 1.87). 10/2005; 15(4):398-406. DOI: 10.1053/j.jrn.2005.07.003
Source: PubMed


The efficacy of a low-protein diet in the secondary prevention of diabetic nephropathy is not established in patients with type 1 or type 2 diabetes mellitus. To determine whether a low-protein diet slows the decrease in glomerular filtration rate (GFR) and decreases the albumin excretion rate (AER) in diabetic patients with incipient and overt nephropathy, we performed a 2-year prospective, randomized controlled trial comparing the effects of a low-protein diet (0.8 g/kg/day) with a usual-protein diet.
The study was conducted in a University hospital and included 63 type 1 and type 2 diabetic patients with either incipient or overt nephropathy and mild renal failure (prestudy GFR, 80 +/- 20 mL/min). The primary outcome measures were decreased in GFR and 24-hour AER.
In the low-protein-diet group, patients were younger (52 +/- 12 versus 63 +/- 9 years old) and more often were type 2 diabetic. During the follow-up period, according to dietary records the low-protein-diet group consumed 16% +/- 3% of total caloric intakes as compared with 19% +/- 4% in the usual-protein-diet group (P < .02), but 24-hour urinary urea excretions did not differ between the two groups. The 2-year GFR decrease was 7 +/- 11 mL/min in the low-protein-diet group and 5 +/- 15 mL/min in the usual-protein-diet group (P = not significant). AER did not increase significantly in the two diet groups during the follow-up period. Blood pressure and glycemic control were similar in the two groups all along the study. The decrease in GFR and AER were also similar in 6 compliant patients according to dietary records and to 24-hour urinary urea excretions from the low-protein-diet group and in 12 patients from the usual-protein-diet group.
A 2-year low-protein diet did not alter the course of GFR or of AER in diabetic patients with incipient or overt nephropathy receiving renin-angiotensin blockers with strict blood pressure control.

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    • "Thus, the treatment strategies for renal failure, including the use of protein-restricted diets [1], have gained increased interest for the treatment of patients with diabetic nephropathy. Despite the few studies that suggest that protein intake restriction fails to improve renal prognosis in type 1 or type 2 diabetic patients with incipient or overt nephropathy[2] and confers renoprotection[3], several findings have demonstrated that a low-protein diet preserves renal function and structure in animal models [4] and in type 2 diabetic patients with macroalbuminuria[5] and improves disease prognosis[6], low-grade inflammation and proteinuria[7] and depressive symptoms[8]. However, there has been increasing concern regarding the risk of the subsequent development of malnutrition due to these diets. "
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