New evidence points to a hormone that leaves muscles gobbling up sugar as if they can't get enough. That factor, which can be coaxed out of fat stem cells, could lead to a new treatment to lower blood sugar and improve metabolism.This new hormone may be a useful alternative or add-on to insulin; it can do essentially the same job, sending glucose out of the bloodstream and into muscle. A team of scientists at University of Texas Southwestern Medical Center, manipulated a key developmental pathway in the fat stem cells of mice to find that the animals showed remarkably low blood sugar levels. The animals' muscles were taking up glucose at two to four times the usual rate thanks to an abundance of glucose transporters at their surfaces. That discovery was all the more striking because the animals also lacked fat stores, a condition known as lipodystrophy that normally results in just the opposite: high blood sugar and diabetes