Hyperglycaemia and insulin resistance are associated with the increased risk of the
metabolic syndrome and other severe health problems. The insulin-sensitive GLUT4 regulates
glucose homoeostasis in skeletal muscle and adipose tissue. In this study, we investigated
whether cacao liquor procyanidin (CLPr) extract, which contains epicatechin, catechin and
other procyanidins, improves glucose tolerance by promoting GLUT4 translocation and
enhances glucose uptake in muscle cells. Our results demonstrated that CLPr increased
glucose uptake in a dose-dependent manner and promoted GLUT4 translocation to the plasma
membrane of L6 myotubes. Oral administration of a single dose of CLPr suppressed the
hyperglycaemic response after carbohydrate ingestion, which was accompanied by enhanced
GLUT4 translocation in ICR mice. These effects of CLPr were independent of
α-glucosidase inhibition in the small intestine. CLPr also promoted GLUT4
translocation in skeletal muscle of C57BL/6 mice fed a CLPr-supplemented diet for
7 d. These results indicate that CLPr is a beneficial food material for improvement
of glucose tolerance by promoting GLUT4 translocation to the plasma membrane of skeletal
muscle.