Link Between Chromium Deficiency and Diabetes?

Years ago, i read of an interesting theory-that diabetes was corellated with a deficiency of the element chromium. Supposedly, countries where chromium was abundant (in the drinking water) had very low rates of diabetes.
Has anyone heard of this, and is there a minimum requirement for chromium , in human metabolism?

Well, I started taking chromium supplements many years before I became diabetic.