Failed my glucose test.... But I'm really healthy!

I already eat a whole food diet with lots of nuts, avocados, lean proteins and veggies. My 'carbs' are fruits and things like black beans. I drink water and some plain kiefer. I walk 5-6 miles a day. I've read vitamin d and magnesium deficiencies can play a role, but I'm truly baffled at how I got to this point. I failed two out of the four blood draws. Anyone else? Any ideas?