Dr. Frank B. Hu of the Harvard School of Public Health and colleagues tracked 26,357 men in the Health Professionals Follow-up Study from 1986-2006, 48,709 women in the Nurses' Health Study from 1986-2006 and 74,077 women in the Nurses' Health Study II from 1991-2007 for about 12-16 years.
Study participants filled out questionnaires on what they ate that were updated every four years. Factored in were adjustments for age, family history, race, marital status, initial red meat consumption and smoking. Other lifestyle factors, such as physical activity, alcohol intake, total caloric intake and diet quality, were also factored in, the study said.
Lead author An Pan of the National University of Singapore, who worked on the study while he was at Harvard, said on average people ate 1.5 servings a day of red meat -- luncheon meat, beef and pork -- but red meat servings varied widely among the study participants.
The study, published in the Journal of the American Medical Association, increasing red meat consumption by a half servings per day was associated with a 48 percent increased risk of type 2 diabetes over a four-year period.
However, those who cut their red meat consumption reduced their type 2 diabetes risk by 14 percent, the study said.