A whole grain of rice has several layers. Only the outermost layer, the hull, is removed to produce what we call brown rice.
If brown rice is further milled to remove the bran and most of the germ layer, the result is a whiter rice, but also a rice that has lost many more nutrients. You end up with a refined starch low on nutrients.
A 2010 study found a higher intake of white rice (5 servings per week) was associated with a higher risk of type 2 Diabetes.
A high intake of brown rice (2 or more servings per week) was associated with a lower risk of Type 2 Diabetes. Definitely worth the change to brown rice!