“Coffee consumption has been consistently linked with a lower risk of type 2 diabetes in cohort studies from across the world,” says epidemiologist Rob van Dam of the National University of Singapore and the Harvard T.H. Chan School of Public Health.

In one analysis of 28 studies that tracked roughly 1.1 million people for an average of 11 years, the risk of type 2 diabetes was 6 to 8 percent lower with each daily cup of coffee, up to six cups a day.

(Keep in mind that a cup is 8 ounces, but many mugs hold 10 to 12 oz. At Starbucks, the only size on some menu boards—a “grande"—is 2 cups, or 16 oz. A “venti” is 2½. Want just 1 cup? Ask for a “short.”)

How might coffee help?

To prove that coffee prevents type 2 diabetes, you’d need a study that randomly assigned people to drink coffee or a placebo for years.

Surprisingly, “in short-term trials, caffeine reduces insulin sensitivity,” says van Dam. In other words, caffeine makes insulin less effective at moving sugar from your blood into your cells, which could eventually lead to type 2 diabetes.

However, “the body adapts to the effects of caffeine, usually within a week or so,” notes van Dam. “In trials lasting several weeks, caffeinated coffee has no detrimental effects on insulin sensitivity.”

But coffee is more than a caffeine delivery system.

“Coffee is complex, and it contains compounds that, in animal studies, have beneficial effects on insulin sensitivity and blood sugar,” says van Dam.

That would explain why studies that track people for years show a lower risk of type 2 diabetes with both regular and decaf coffee.

“Components of coffee other than caffeine may be responsible for the beneficial effects of coffee consumption on diabetes risk,” says van Dam.

Photo: Chris Knight/unsplash.com.