© Lee et al./Cell Metabolism 2016
This visual abstract depicts what Lee et al. found, how glucose utilization by brown fat in humans is coupled with heat production in a circadian manner. Higher brown fat abundance correlates with lesser glycemia variability, suggesting that brown fat may help buffer glucose fluctuations and maintain whole-body glucose homeostasis over time.
Brown fat is well known for protecting the body from cold temperatures, and now researchers have discovered that this cell type in humans
shows circadian rhythms in its consumption of glucose--an energy fuel for heat production. These rhythms, which rise just before waking, may have evolved as a thermal defense mechanism to prepare our ancestors for hunting and gathering in the coldest morning hours. The research appears March 10 in
Cell Metabolism.
"Marked day-to-day glucose variations have been proposed to be a precursor of diabetes," says lead author Paul Lee, a clinician scientist and endocrinologist at the Garvan Institute of Medical Research in Australia.
"For modern humans who do not rely on it for cold protection, the energy-consuming brown fat rhythm may act as a glucose buffer, smoothing glucose fluctuations and lessening the stress on the pancreas."
In the survival hierarchy, the maintenance of the body's core temperature trumps the need for food and water. In response to cold temperatures, brown fat consumes a large quantity of glucose and lipids as a fuel source for generating heat and keeping the body warm. By the same token,
cold-induced activation of brown fat burns calories and lowers glucose levels, thereby protecting animals against obesity and diabetes. But it has not been clear whether brown fat regulates glucose levels in the absence of cold exposure.
Comment: Big pharma lobbyists creaming tens of billions out of the federal government in a variety of schemes