Replacing white rice in your diet with brown rice can reduce your risk of developing diabetes by about 36%. If you don't like the flavour of brown rice, even substituting half of your white rice for brown rice (at the same meal or at separate meals) can reduce your risk by 16%.
An analysis of the results of the Health Professionals Follow-Up Study and the Nurses' Health Study I and II found that people who consumed five or more servings of white rice per week had a 17% increased risk of diabetes, compared to people who ate less than one serving per month. But eating two or more servings of brown rice per week was associated with an 11% reduced risk of developing type 2 diabetes, compared to eating less than one serving of brown rice per month.
The reason why brown rice can reduce your diabetes risk and white rice increase it is that brown rice is a whole grain. This means that it has more fiber as well as vitamins and minerals in it. This is why brown rice will keep you feeling full for longer and often in many cases can make you feel full quicker (i.e. after eating less). Because it is whole grain, brown rice is also lower in GI (66 vs 89) so it doesn't produce the same spikes in your blood sugar levels.
USDA National Nutrient Database for Standard Reference (www.nal.usda.gov/