UCLA researchers discover molecular mechanism behind drink’s prophylactic effect.
Coffee, that morning elixir, may give us an early jump-start to the day, but numerous studies have shown that it also may be protective against type 2 diabetes. Yet no one has really understood why.
Now, researchers at UCLA have discovered a possible molecular mechanism behind coffee’s protective effect. A protein called sex hormone–binding globulin (SHBG) regulates the biological activity of the body’s sex hormones, 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 current edition of the journal Diabetes, first author Atsushi Goto, a UCLA doctoral student in epidemiology, and Dr. Simin Liu, a professor of epidemiology and medicine with joint appointments at the UCLA School of Public Health and the David Geffen School of Medicine at UCLA, show that women who drink at least four cups of coffee a day are less than half as likely to develop diabetes as non-coffee drinkers.
When the findings were adjusted for levels of SHBG, the researchers said, that protective effect disappeared.
The American Diabetes Association estimates that nearly 24 million children and adults in the U.S. — nearly 8 percent of the population — have diabetes. Type 2 diabetes is the most common form of the disease and accounts for about 90 to 95 percent of these cases.
Early studies have consistently shown that an “inverse association” exists between coffee consumption and risk for type 2 diabetes, Liu said. That is, the greater the consumption of coffee, the lesser the risk of diabetes. It was thought that coffee may improve the body’s tolerance to glucose by increasing metabolism or improving its tolerance to insulin.
“But exactly how is elusive,” said Liu, “although we now know that this protein, SHBG, is critical as an early target for assessing the risk and prevention of the onset of diabetes.”