Effect of oral supplementation with whey protein on muscle mass in adults with type 2 diabetes mellitus: a systematic review of randomized controlled trials

Objective: To investigate the overall effect of whey protein supplementation on skeletal muscle mass in adults with type 2 diabetes mellitus (T2DM). Methods: Systematic review of reports on corporal muscle mass from clinical trials that assessed the use of whey protein supplementation by means of validated techniques in patients with T2DM. PubMed, SCOPUS, Web of Science, LILACS, and SciELO databases were searched up to April 2022. Risk of bias was assessed by the Cochrane Collaboration Risk of Bias tool. We conducted a qualitative synthesis of information. Results: Four studies (424 participants) that met the selection criteria were identified out of 1,787 records. Of these, 3 studies assessed the total muscle mass using dual-energy X-ray absorptiometry (DXA), and 1 reported changes to the transverse diameter of the vastus lateralis muscle with ultrasound imaging. In the intervention groups, DXA assessments demonstrated an increase in total muscle mass in 3 studies and in the appendicular muscle mass in 2. Changes to the proportion of muscle mass were not seen in the DXA studies and only a discrete difference was seen in the comparative groups studied by ultrasound imaging. Conclusion: Following the administration of whey protein supplementation in patients with T2DM, a partially positive effect was seen in skeletal muscle mass gain with a moderate certainty of evidence.