Bad news I's afraid. Oat bran is about 60% carbohydrate.
You can see the details here on our nutritional index: Decarb Nutritional Index
If you have to have it keep the quantities down!
Side note: I also have a concern that oat bran sucks up cholesterol from the bowel.
Now in a cholesterol fearing world that would be a good thing. And in fact I used to eat buckets of oat bran and as a result, my blood cholesterol levels were below 4. However more and more studies are showing that low cholesterol levels are BAD for your overall health and thus it seems silly to me to eat the powder of a hard grain that was never intended for human consumption, just so that it can mop up cholesterol that the body has gone to great lengths to preserve. (Cholesterol excreted from the gall bladder in bile salts is normally re-absorbed because it is so valuable).