If I make only one point in this thread, it is this:
If you are a long-time runner who has been on a high-carb diet, have your A1c AND CAC checked. Don't rely on your doctor to bring this up, as they are used to overweight, sedentary people coming through their office all day and are likely not aware of the elevated risk that runners face with undiagnosed diabetes!
My doctor never brought up my A1c and it was never tested, but I had many issues that in hindsight were indicative of pre-diabetes. Probably the best -documented case of an avid runner with pre-diabetes is Dr. Mark Cuccuzzella (
http://naturalrunningcenter.com/category/markc/
http://www.letsrun.com/forum/flat_read.php?board=1&id=8818588&thread=8818588#8818588
), who was performing at a high level with the disease, and went on to reverse it.
The perception of running as protective is too heavily relied upon for those of us on the outlier end of dedication to this sport. Be pro-active, it might save your life!