GCG and diabetes mellitus: In addition to the report of Jiang et al., our results provide important aspects of the effect of HIF-1α on the induction of obesity-induced diabetes, namely, the involvement of GLP-1 in improving glucose tolerance in ahKO mice and the involvement of HIF-1α expressed in adipocytes, but not in macrophages, in the initiation of obesity-induced macrophage infiltration into adipocytes, as described above.