My brother was diagnosed with non-insulin dependent diabetes mellitus. What does this mean?

Type 2 diabetes. The first source of information would be the american diabetes association, which has available a huge amount of literature on the subject. One can look up diabetes on google - but be careful that you realize that the material might not necessarily be checked for acuracy. I have recently released an informational dvd called "diabetes swweet 'n simple" which discusses the basics of the disease.
No insulin needed. That means his diabetes can be treated with oral medications and that he is not a type 1 diabetic. The Insulin in his body is not working well so the treatment is to do anything to make the Insulin works better: weight loss, increase activities/exercise, medications...