Protein restriction for diabetic kidney disease

Area of Science:

• Nephrology
• Endocrinology
• Dietary Science

Background:

• Diabetic kidney disease (DKD) is a primary cause of global kidney failure.
• Dietary protein restriction has been historically proposed to slow chronic kidney disease (CKD) progression in DKD patients.
• The definitive benefits and risks of dietary protein restriction in DKD progression remain unclear.

Purpose of the Study:

• To evaluate the efficacy and safety of low protein diets (LPD) (0.6-0.8 g/kg/day) in preventing CKD progression and kidney failure in adult DKD patients.
• To assess the impact of LPD on mortality, adverse events (malnutrition, hyperglycemia, quality of life), and patient compliance.

Main Methods:

• Systematic review and meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs.
• Included studies compared LPD (0.6-0.8 g/kg/day) with usual or unrestricted protein diets (UPD) (≥1.0 g/kg/day) in non-dialysis DKD patients for at least 12 months.
• Data synthesis using random-effects models; risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI); Grading of Recommendations Assessment, Development and Evaluation (GRADE) for evidence certainty.

Main Results:

• Eight studies with 486 participants were included; intervention duration averaged two years.
• Low certainty evidence suggests LPD has little to no effect on death (RR 0.38, 95% CI 0.10-1.44) or kidney failure incidence (RR 1.16, 95% CI 0.38-3.59).
• Uncertainty exists regarding LPD's effect on glomerular filtration rate decline (MD -0.73 mL/min/1.73 m²/year) and creatinine clearance (MD -2.39 mL/min/year); proteinuria changes were also uncertain. Malnutrition was rare, but compliance was unsatisfactory in nearly half of studies. No hyperglycemic events were reported.

Conclusions:

• Dietary protein restriction in DKD demonstrates uncertain effects on kidney function decline over time.
• LPD appears to have minimal impact on the risk of death and kidney failure.
• Further large-scale pragmatic RCTs are needed to clarify optimal protein intake levels, compliance, and long-term effects on quality of life and adverse events in various CKD stages.