Current Guidelines on Dietary Protein Intake for Patients with Diabetic Kidney Disease: A Scoping Review

International nutritional guidelines vary in their recommendations, as well as in the reporting quality of the underlying evidence. An underreported recommendation in guidelines for people with type II diabetes concerns the optimal protein intake in the case of chronic kidney disease (CKD).

In this review, we analyze the protein intake recommendations from worldwide practice guidelines for type II diabetes and CKD.

We conducted a systematic search in the online databases PubMed, Embase, and Cochrane Database of Systematic Reviews, as well as websites, according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, and up to 31 January, 2023. We included nutritional and clinical practice guidelines on protein intake in patients with type II diabetes and CKD of different stages. We assessed the quality of the guidelines using the instruments Appraisal of Guidelines for Research & Evaluation Instrument (AGREE II) and AGREE Recommendation Excellence. We assessed the quality of the underlying scientific evidence using the evidence pyramid and the level of evidence categorization.

Of 24 included guidelines, 5 met the quality assessment of all instruments. Their evidence was based on an overlapping number of randomized controlled trials (RCTs). Nevertheless, their protein intake recommendations differed, ranging from no restriction to restriction to 0.8 g/kg body weight/d.

The reason for the discrepancy of protein intake recommendations between different guidelines could not be determined conclusively, as the methodology of evidence assessment was often insufficiently reported. More long-term and good-quality RCTs are needed. We recommend the use of rigorous development and quality assessment tools in the development of clinical practice guidelines for patients with CKD and type II diabetes.