The study followed 1,892 Japanese people aged 40-79 over the course of 14 years. 280 people over that time period developed diabetes type II. They found that those that had the highest fiber intake had about half the likelihood of developing (0.53) diabetes compared to those who had the lowest fiber intake. They found that this correlation of lowered diabetes risk was associated with both insoluble and soluble fiber.
TL;DR Higher dietary fiber intake was associated with a lower risk of type 2 diabetes