They followed 114,996 men & 92,483 women 50-71 years old w/o evidence of heart disease, cancer or diabetes from 1995 to 2006. A good lifestyle was characterized as consisting of regular physical activity , maintaining normal body weight (body mass index <25kg/m2), eating a healthy diet, avoiding tobacco use, and consuming moderate alcohol.
While each of these 5 lifestyle factors was independently associated with 31-39% lower risk of developing diabetes, the more lifestyle factors one engaged in one's daily life, the lower one's risk for developing diabetes, such that those who reported all 5 factors had 72-84% lower risk compared to those who reported none.
If you think of overweight & obesity as the summation of healthy nutrition & regular physical activity, it appears to make sense that weight appeared to play the largest factor in development of diabetes. Regardless, this observation study provides more evidence that our behavior determines our risk for developing diabetes. So if we don't want to deal with the sequelae and complications of diabetes, eg stroke, heart attack, kidney failure/dialysis/transplant, blindness, amputations, and erectile dysfunction, we better change our lifestyle now, while we have a chance!