MiR-199a is overexpressed in plasma of type 2 diabetes patients which contributes to type 2 diabetes by targeting GLUT4.

Decreased GLUT4 expression and impaired GLUT4 cell membrane translocation are involved in type 2 diabetes mellitus (T2DM) pathogenesis so the factors impacting GLUT4 expression may be associated with T2DM. In this study, we identified four miRNAs: miR-31, miR-93, miR-146a, and miR-199a which suppress GLUT4 expression in HEK293T cells. Subsequently, we determined expression of these four miRNAs in plasma samples of T2DM patients, T2DM susceptible individuals, and healthy controls and found miR-199a was overexpressed in patients' plasma compared with healthy control. Because the miR-199a binding site in GLUT4 3'UTR is highly conserved among vertebrates, we detected the glucose uptake in rat L6 myoblast cells through gain- and loss-of-function of miR-199a. We found that miR-199a can repress glucose uptake in L6 cells, which was rescued by GLUT4 overexpression. These results indicate that T2DM patients may have a high level miR-199a that reduce GLUT4 expression and contribute to the insulin resistance. Hence, miR-199a may be a novel biomarker for risk estimation and classification in T2DM patients.