Before any kind of general statement is made that whole grains fight Type 2 diabetes, it is important to know that in some cases, whole grains are a culprit in Type 2 diabetes.
Sometimes, a person can be gluten sensitive and when that happens, the consumption of grain can cause an allergy-mediated reaction that results in a rapid rise or a rapid drop in blood sugar levels.
Food containing gluten include:

• wheat
• oats
• rye
• barley
• pasta
• cereal
• beer and
• spelt

Many processed foods also contain gluten.
Gluten free foods, including bread and pasta, can be purchased from most supermarkets and health food stores.
So consider this for a few moments and check it out yourself to see if it is possible that grains are affecting your blood sugar levels.
You can do this by simply measuring your blood sugars after you eat...
about an hour to an hour and a half later...
and if you notice wide swings, be suspicious that grains are responsible for them.
Keep more extensive records of what you are eating and what your blood sugar levels are, and then determine whether or not there is a distinctive pattern there.
If grains are not causing you any fluctuations in your blood sugars, then you probably don't have a problem with them.
There are several reasons why whole grains can be beneficial in people with Type 2 diabetes:

• whole grains have higher amounts of chromium and zinc in them than processed grains.
  The higher levels allow more even blood sugar levels
• whole grains contain much more fiber; they have not been refined, which means the whole grain is retained, rather than just the endosperm.
  Because of this, whole grains have more nutritional value than refined or processed grains.
  And of course the fiber in whole grains prevents you from quickly digesting the food.
  Slower absorption of nutrients also means slower absorption of sugar into your bloodstream
• whole grains are also loaded with dozens more phytonutrients than processed foods.
  Some of these phytonutrients are responsible for blood sugar regulation.
  Although we don't know all the phytonutrients that are responsible for blood sugar regulation, generally speaking the greater the variety of phytonutrients that are consumed, the better one's health is.
  That means that naked food, like processed grains, which has been stripped of phytonutrients is clearly not as healthy for us as the whole grains

The whole grain group: Now this group includes brown rice, oats, barley, corn and all the products made from whole grains:

• bread
• cereals
• pasta and more

In countries where grains are part of the staple diet, Type 2 diabetes is much less common.
Why? Whole grains are filling but have little fat and no cholesterol.
When choosing grains, be guided by the glycemic index.
So go for those whole grains.
Test them out yourself.
You will find they are pretty tasty!