Effects of four-weeks porcine-collagen hydrolysate consumption on glucose concentrations, glycemic variability, and fasting/postprandial cardiometabolic risk markers in men and women with overweight or obesity: A randomized, controlled trial

Background: Different collagen hydrolysate sources have reduced fasting glucose concentrations. Although porcine-derived collagen hydrolysate predicts in vitro the highest potency for improving glucose metabolism, these effects have not been studied in humans. Aim: To evaluate the effects of porcine-derived collagen hydrolysate on continuously monitored glucose concentrations in real-life conditions in individuals with overweight/obesity. Additionally, postprandial responses following a mixed meal test were examined. Methods: Fifty-six men and women participated in this randomized placebo-controlled parallel trial. After a two-week run-in period, participants consumed daily for four weeks 10 g porcine-derived collagen hydrolysate or placebo (erythritol). The primary outcome parameter was the interstitial glucose area under the curve (AUC) during daytime (07:00 to 22:00) measured during three consecutive days. In addition, glycemic variability (GV) was quantified. For this, a continuous glucose monitor (Freestyle Libre ProiQ, Wiesbaden, Germany) was used at the end of the run-in and intervention periods. Postprandial glucose, insulin, and triacylglycerol concentrations were also evaluated after a mixed meal tolerance test. Furthermore, fasting glucose, insulin, hemoglobin A1c (HbA1c), homeostatic model assessment for insulin resistance (HOMA-IR), HOMA of ß-cell function (HOMA-ß), and triacylglycerol changes were analyzed. Physical activity profiles and dietary intakes were monitored to exclude confounding by these lifestyle factors. Results: Collagen hydrolysate consumption did not significantly affect daytime interstitial glucose AUC concentrations (95%CI for the effect size: -5.1, 30.0 mmol/(L*h); p-value = 0.159), but increased several GV metrics: standard deviation (95%CI: 0.0, 0.2 mmol/L; p-value = 0.011), continuous overall net glycemic action (CONGA-4) (95%CI: 0.1, 0.4 mmol/L; p-value = 0.015), coefficient of variation (95%CI: 0.1, 3.0 %; p-value = 0.036), M-value (95%CI: 0.2, 1.8; p-value = 0.036), and mean amplitude of glycemic excursions (MAGE) (95%CI: 0.2, 1.8 mmol/L; p-value = 0.036). Furthermore, the postprandial glucose AUC after the mixed meal test significantly increased (95%CI: 0, 103 mmol/L*4-h; p-value = 0.049), as well as fasting insulin concentrations (p-value = 0.005), HOMA-IR (p-value = 0.008), and HOMA-ß (p-value = 0.009). Other parameters, anthropometrics, physical activity, and energy/nutrient intakes were not significantly changed. Conclusion: Four-week collagen hydrolysate intake did not change free-living glucose concentrations, but increased GV, postprandial glucose AUC, fasting insulin, HOMA-IR, and HOMA-ß. However, these changes were small with limited clinical relevance. Therefore, it can be concluded that this porcine-derived collagen hydrolysate does not improve glucose metabolism or other cardiometabolic risk markers. Clinical trial registration: This clinical trial was registered in November 2021 as NCT05282641.