P4HB and Insulin resistance: GRP78, PDIA1 and XBP1 in situ expression levels were significantly correlated with metabolic variables such as ISI-M (GRP78: r=−0.6, p=0.01; PDIA1: r=−0.6, p=0.03) (Fig. 3g,h), basal ISR (GRP78: r=0.8, p=0.002; PDIA1: r=0.6, p=0.01; XBP1: r=0.6, p=0.02) (Fig. 3i–k), basal insulin (PDIA1: r=0.8, p=0.001) (Fig. 3l) and 2 h glucose levels at OGTT (GRP78: r=0.7, p=0.01; PDIA1: r=0.7, p=0.009; XBP1: r=0.7, p=0.005) (Fig. 3m–o), denoting a close link between insulin resistance, consequent high basal insulin secretion and ER stress molecular markers.