Ok back to the rice diet with ancient China. I believe they didn't have a problem with diabetes because even when they ate a lot of rice, there are not taking in excess calories. I've said this in the other thread about red meats that caloric intake play a bigger role than eating sugar when it comes to getting diabetes. After looking around a bit I found this article.
http://diabetes.diabetesjournals.org.../3566.abstract
"In this study, a high-sucrose intake as part of an eucaloric, weight-maintaining diet had no detrimental effect on insulin sensitivity, glycemic profiles, or measures of vascular compliance in healthy nondiabetic subjects."