Whey Protein Supplementation and Type 2 Diabetes Mellitus Risk Factors: An Umbrella Systematic Review of Randomized Controlled Trials

Emerging research suggests whey protein (WP) supplementation may modify type 2 diabetes mellitus (T2DM) risk factors, including glucose control. As systematic reviews and/or meta-analyses of randomized controlled trials (RCTs) gain importance in nutrition literature, we conducted an umbrella systematic review to chronicle published systematic reviews and/or meta-analyses of RCTs pertinent to WP supplementation and T2DM modifiable risk factors. This review was conducted in accordance with Preferred Reporting Items for Overviews of Reviews standards. Potentially eligible articles were identified via a systematic search of 5 electronic health research databases (PubMed, Cochrane Library, CINAHL [EBSCO], Scopus, and SPORTDiscus [EBSCO]). Included articles were assessed for quality using the "A MeaSurement Tool to Assess systematic Reviews 2" critical appraisal tool. Thirteen articles, representing 109 unique RCTs, of the 2205 identified articles met the inclusion criteria. Nine articles (69%) were deemed high quality, 2 (15%) moderate quality, and 2 (15%) low quality. Findings from this umbrella review of 13 systematic reviews, including 12 meta-analyses, suggest WP may lower hemoglobin A1c, homeostasis model assessment of insulin resistance, and fasting insulin in groups classified as overweight/obese or at risk for or with metabolic syndrome; blood triglycerides in groups classified as overweight/obese or at risk for or with metabolic syndrome; and blood pressure in groups classified as overweight/obese. WP did not differentially affect C-reactive protein, body weight, body mass index, or waist circumference, nor did it adversely affect any T2DM risk factors. Insufficient evidence precluded assessing the influence of WP on glucose control-related outcomes in groups classified at lower risk for T2DM. Information regarding WP dose, duration, or types was insufficient to draw conclusions. Collectively, evidence suggests WP supplementation may improve multiple clinical indicators of glucose control, along with triglycerides and blood pressure, in groups of adults at increased risk of developing T2DM.