Diabetes mellitus is a metabolic disease characterized by an increase in blood glucose levels due to lack of insulin secretion. Previous studies have confirmed that PICK1 is critical for both beta-cell function and glucose homeostasis. The aim of this study was to investigate the role of PICK1 in response to high glucose-induced beta-cell dysfunction and the molecular mechanism of regulation of PICK1. We found that overexpression of PICK1 in db/db diabetic mice significantly improved glucose tolerance and increased insulin release. High glucose treatment of Min6 cells inhibited PICK1 expression, and overexpression of PICK1 protected against high glucose-induced pancreatic cell dysfunction. Activation of the PI3K/Akt pathway by PICK1 in Min6 cells resulted in increased GLUT2 expression and this increase was abolished by treatment with a PI3K-specific inhibitor. Further, we showed that expression of PICK1 is negatively regulated by miR-139-5p through directly targeting its 3'UTR. These data suggested that PICK1 may participate in the functional protection of pancreatic beta-cells through PI3K/Akt signaling, promote insulin secretion, and delay the progression of diabetes, and is negatively regulated by miR-139-5p, further clarifying the regulation of pancreatic beta-cell function. (C) 2019 Elsevier Inc. All rights reserved.