This study assessed the effects of dietary habits and other lifestyle factors on the incidence of diabetes in a rural Japanese population. This 10.3-year study investigated a cohort of 1,995 men and 3,670 women aged 40-69 years without diabetes at baseline who underwent health check-ups between April 1990 and March 1992. Participants were followed up until diabetes was confirmed or until the end of 2006. The incidence of diabetes was determined from fasting and random levels of plasma glucose, HbA1c levels or being under medical treatment for diabetes. Principal component analysis identified a major dietary pattern characterized by more frequent consumption of vegetables, potatoes, seaweeds, fruits and soybean products that we labeled "healthy". Diabetes developed in 446 of the participants during 58,151 person-years of follow-up. Consuming a healthy diet was associated with a lower risk of diabetes (multivariable-adjusted hazard ratio for highest vs lowest quartiles, 0.78 [95% CI, 0.61- 0.95]. In addition, scores for a healthy diet were associated with a lower risk for diabetes among persons who consumed regular meals (0.76 [0.58-0.96]), persons with an exercise habit (0.65 [0.44-0.96]) and non- and ex-smokers (0.72 [0.53-0.96]). Our findings suggest that consuming a healthy diet is associated with a lower risk for diabetes among the Japanese, particularly among those who eat regularly, those who habitually exercise and non- and ex-smokers.