"I think the difference is enough to encourage people at least not to increase red meat consumption, and then think about ways to reduce the consumption," said the study's lead author An Pan, a professor at the National University of Singapore, in an email to Reuters Health.
The study can't prove eating red meat causes diabetes, but past studies have tied eating it to the risk of type 2 diabetes, which is what happens when the body either does not produce enough insulin or ignores the insulin it needs to turn food into energy.
About 26 million Americans have diabetes and between 90 and 95 percent of those cases are type 2, according to the U.S. Centers for Disease Control and Prevention.
Earlier studies on red meat - such as beef, pork and lamb - didn't account for participants changing how much of it they ate over time, Pan said.
For the new study, Pan and colleagues followed about 149,000 U.S. men and women for 12 to 16 years. Every four years, the participants were asked about how much red meat they ate per day.
Overall, the participants reported eating between half a serving and two servings every day. A serving is equal to about two slices of bacon, one hot dog or one three-ounce hamburger.
By the end of the study, there were 7,540 cases of type 2 diabetes reported.
There were 1,758 cases of diabetes among the 41,236 people who didn't change how much red meat they ate on a daily basis.
People who added more than half a serving per day of red meat had about two cases of diabetes per 300 people, compared to about one case in the group who didn't change the amount of red meat they ate.
Decreasing the amount of red meat a person ate was not tied to any differences in the first four years.
But after the researchers took into account factors such as how much red meat people initially ate, whether they were married, and family history of various conditions, eating less red meat was tied to a 14 percent decreased risk of developing type 2 diabetes over the next 12 to 16 years.
Pan told Reuters Health it could be that "if you are doing some ‘bad' things, you will see the impact immediately, but for the ‘good' lifestyle habit to have an effect, you may need to wait longer and accumulate more moderate changes."
RED MEAT v. FAT
In an invited commentary accompanying the new study in JAMA Internal Medicine, William Evans, head of the Muscle Metabolism Discovery Performance Unit at GlaxoSmithKline in Durham, North Carolina, said it may be misleading to simply warn people away from "red meat."
"I think fundamentally ‘red meat' has become a pejorative term… There are cuts of beef that have less fat than some chicken," Evans, who also teaches at Duke University, said.
Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at Tufts University in Boston, said it's important to consider the whole diet.
"If someone reduces their meat intake by substituting cheese, I don't think they're going to realize any benefit," said Lichtenstein, who was not involved with the new research.
