Effect of Anthocyanins Supplementation on Serum IGFBP-4 Fragments and Glycemic Control in Patients with Fasting Hyperglycemia: A Randomized Controlled Trial

BACKGROUND: Insulin-like growth factor binding protein-4 (IGFBP-4) fragments have been shown to be associated with cardiometabolic diseases. Anthocyanins as a subgroup of natural polyphenols could have benefits on treating cardiometabolic diseases. The aim of this study was to examine the effects of purified anthocyanins on serum IGFBP-4 fragments and glycemic control in patients with fasting hyperglycemia. METHODS: A set of 121 participants with elevated fasting glucose (≥5.6 mmol/L), who were originally randomly assigned to anthocyanins (320 mg/day) or placebo groups, were included in this study. Serum IGFBP-4 fragments, fasting and postload glucose, insulin, and C-peptide after a three-hour oral glucose tolerance test (OGTT) were measured at baseline and at the end of 12 weeks. RESULTS: Compared with placebo, anthocyanins increased serum IGFBP-4 fragments (net change 8.33 ng/mL, 95% CI [1.2, 15.47], p=0.023) and decreased fasting glucose (−0.4 mmol/L [−0.71, -0.1], p=0.01), 2-hour C-peptide (−1.02 ng/mL [−1.99, −0.04], p=0.041) and the 3-hour area under the curve (AUC) of C-peptide (−2.19 [−4.11, −0.27], p=0.026). No other significant difference in parameters for glycemic control and insulin resistance was observed. CONCLUSION: Anthocyanins supplementation for 12 weeks improved serum IGFBP-4 fragments and decreased fasting glucose and postload C-peptide in patients with fasting hyperglycemia. Further studies are needed to confirm our findings and clarify the potential mechanism. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02689765. Registered on 6 February 2016, https://clinicaltrials.gov/ct2/show/NCT02689765.