Help! My doctor was too quick to label me a diabetic, will my insurance suffer?

I am seeing a "top doc" (one of several doctor's in my are who were given rave reviews by their peers) and he doesn't believe I am diabetic. He thinks I may be borderline or high glycemic. He doesn't understand why my previous doctor earlier this year diagnosed and labeled me as one. He also warned me that there is a price to pay when insurance companies receive this type of diagnosis. He said doctors should be absolutely sure before they forward such information to insurance companies. I advised him that my previous doctor made me see an eye specialist, and gave me a pneumonia shot, and scheduled me to see a dietitian. He almost gasped. He said he works with hundreds of diabetics (which are all doing absolutely great under his care according to written reviews) and he said there is NO WAY that I am a diabetic. He said an A1C should be combined with a fasting glucose test and that my previous doctor should not have diagnosed me with diabetes based only by the numbers of my A1C. He said he will test me again but based on my previous scores, I AM NOT a diabetic. What can I do to get my insurance company to believe me and take this OFF of my record. He said he will send them a letter (after he test me) stating that I am high glycemic but am now at normal levels due to diet and exercise. Will this be enough to take this diabetes diagnosis OFF of my medial records with the insurance company even though a previous doctor labeled me a so?