Hi DavidJ,
Sorry to hear about your problem and can quite understand why it is so important in your particular line of work.
Your situation sounds a little bit unusual. However, one possible explanation could be that you are a well-controlled Type 2 diabetic such as me.
I was diagnosed nearly nine years ago and my situation gradually progressed until I reached a HbA1C of 9.5%. However, I have almost totally normalised my blood glucose levels over the last twelve months by making changes to my diet. These days, I could easily get past most testing methods because my HbA1c was 5.3% last time - also, my fasting blood glucose levels are always between 3.4 and 6.8 (100% of the time) - i.e. non-diabetic numbers. Despite those levels, I know that if I gorged myself on sugar or carbohydrate my levels would quickly shoot up into double figures.
It has made me realise that it is possible that there may be some undiagnosed Type 2 diabetics out there who may never get diagnosed because they have a diet that is naturally low in sugar and carbohydrate - i.e. basically, they could be maintaining good diabetic control by accident rather than by design. In such cases, only a glucose tolerance test would show the person to be diabetic.
Had you been eating differently prior to your high readings?
Hope that things will work out OK for you.
John