| Diabetes doesn't effect the lens or the cornea, and for your vision to change like that it would have had to flex your lens a smudge inward to a smudge outward, and back again. High blood sugar effects the retina and the optic nerve. This is why high blood sugar for extended periods of time can make things blurry. Running high for loooong periods of time cause diabetic retinopathy and/or macular edema which can really blur your sight.
Does this mean that diabetes caused you to be near-sighted to far sighted and back again? Maybe, but from what I know about the eyes and diabetes it doesn't seem likely.
Hopefully your appointment will shed more light. | 
