The just-released study in the Archives of Internal Medicine says drinking just one cup of coffee a day - regular or de-caf - or a cup of tea - can reduce the risk of getting type-2 diabetes by 7 percent.
And drinking three to four cups each day can lower risk by 25 percent.
"I think the suggestion from this survey is very strong," said Dr. Xavier Pi-Sunyer, chief of endocrinology at St. Luke's Roosevelt Hospital.
Type-2 diabetes is a growing health problem worldwide. It's an illness where the body becomes resistant to the hormone insulin. As a result, sugar builds up in the blood. Being overweight increases the chance of getting it.
"Type-2 diabetes makes up more than 90 percent of the diabetic patients around the world," Dr. Pi-Sunyer said. "It's the big chunk of diabetes."
Dr. Pi-Sunyer is encouraged by the study results.
"This does give the suggestion that coffee's good for you, with regard to not developing diabetes," he said.
The study, conducted by the University of Sydney, is more like a survey, culling results of 18 other studies done as far back as 1966.
So what's in a cup of coffee or tea that helps prevents type-2 diabetes? The survey doesn't say.
"It's unlikely to be caffeine, because decaf also does it," Dr. Pi-Sunyer said. "And there are other studies in the past that show this.
This is just preventative, so if you already have type-2 diabetes, there is no proof that coffee or tea will help.