Impact of low-protein diet on cardiovascular risk factors and kidney function in diabetic nephropathy: A systematic review and meta-analysis of randomized-controlled trials

Aim: To assess the efficacy of low-protein diets (LPD) on cardiovascular risk factors and kidney function in diabetic nephropathy (DN) based on randomized controlled trials (RCTs). Methods: A comprehensive systematic search was undertaken in PubMed/MEDLINE, Web of Science, SCOPUS and Embase databases from inception until January 2022 without using time or language restrictions. RCTs which reported the effects of LPD on cardiovascular risk factors and kidney function in DN were considered. Results: The results of the present study showed that a LPD significantly reduces urinary urea (WMD: -244.49 g/ day, 95 % CI: -418.83, -70.16, P = 0.006) and HbA1c (WMD: -0.20, 95 % CI: -0.39, -0.01, P = 0.036) levels. However, the results did not show neither significant nor beneficial effect on other renal function and cardiovascular risk factors. Furthermore, the results of subgroup analysis showed LPD caused a further decrease in HbA1c during the follow-up period of <= 24 weeks, protein intake less than 0.8 g/kg/d and in individuals younger than 50 years. Albuminuria also showed a greater reduction in people under the age of 50 with type 1 diabetes (DMT1) following a LPD. Conclusion: The results of the present study showed that LPD significantly reduces urinary urea and HbA1c.