Eating nuts or peanut butter may help prevent type 2 diabetes, according to a study of over 83,000 women. Scientists at the Harvard School of Public Health studied the eating habits of 83,818 female nurses aged between 34 and 59 years old, with no history of diabetes, cardiovascular disease or cancer. The participants completed a dietary questionnaire at the start of the survey in 1980. They were then followed up for 16 years, by which time 3,206 had developed type 2 diabetes.