Fibroblast growth factor 21: new insights from human studiesHansen, Jakob S.; Plomgaard, PeterCardiovascular Endocrinology: September 2016 - Volume 5 - Issue 3 - p 112–116 doi: 10.1097/XCE.0000000000000084 Review Articles Abstract Author Information Fibroblast growth factor 21 (FGF21) is a novel metabolic regulator that holds promise as a therapeutic target in the treatment of type 2 diabetes and obesity. The regulation of FGF21, however, is only emerging. Most of the existing evidence is derived from animal studies – particularly mice – where repeated measurements of hormones are difficult. Over the last decade, several studies evaluating the regulation of FGF21 in human physiology have emerged in the literature. These have shown that plasma FGF21 is an acutely regulated hormone and that the glucagon-to-insulin ratio seems to be pivotal in the regulation of FGF21. In the present narrative review, we evaluate the regulation of FGF21 in humans with a focus on the regulatory role of the glucagon-to-insulin ratio. aDepartment of Clinical Biochemistry (KB3011) bThe Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark Correspondence to Peter Plomgaard, MD, Department of Clinical Biochemistry (KB3011), Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark Tel: +45 35 45 39 46; e-mail: firstname.lastname@example.org Received June 7, 2016 Accepted June 23, 2016 Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.