I just read 2 studies done this year comparing vegans, veggies & meat eaters. It turns out that in the case of Adventists vegans have less chance of getting diabetes & metabolic syndrome than either of the other groups. As Adventists tend to live similar lives except for eating habits it seems likely that all things being equal you will do better eating vegan if you want to avoid these issues.
Here are the abstracts if you want to read them:
Diabetes
Metabolic Syndrome