COFFEE MAY GIVE US AN EARLY JUMP-START, but numerous studies have shown that it also may be protective against type 2 diabetes. Yet no one has really understood why. Now, UCLA researchers have discovered a possible molecular mechanism behind coffee’s protective effect: a protein called sex hormone-binding globulin (SHBG).
The protein regulates the biological activity of testosterone and estrogen, which have long been thought to play a role in the development of type 2 diabetes. And coffee consumption, it turns out, increases plasma levels of SHBG.
Reporting with colleagues in the journal Diabetes, Atsushi Goto, a doctoral student in epidemiology, and Simin Liu, M.D., professor of epidemiology, show that women in the study who drank at least four cups of coffee had significantly higher levels of SHBG and were less than half as likely to develop diabetes as non-coffee drinkers.
A large body of clinical studies has implicated the important role of sex hormones in the development of type 2 diabetes, and it’s known that SHBG not only regulates the sex hormones that are biologically active, but may also bind to receptors in a variety of cells, directly mediating the signaling of sex hormones.
“It seems that SHBG in the blood does reflect a genetic susceptibility to developing type 2 diabetes,” Dr. Liu says. “But we now further show that this protein can be influenced by dietary factors such as coffee intake in affecting diabetes risk – the lower the levels of SHBG, the greater the risk beyond any known diabetes risk factors.”
Unfortunately, decaf doesn’t seem to convey the same benefit. Says Goto: “You probably have to go for the octane!”