I'm kind of late to the party, too.
For whatever it's worth, testing supplies including test strips are covered under Medicare A. There is an annual deductible but it is a good deal, as medicare A is free. Semi annual labs are also free. I don't know if there's a deductible on that, or not. I do not believe any supplemental covers test strips at all.
Bpb didn't ask, but Medicare B covers annual vision exams for retina issues - but not prescription for glasses. Deductible and copays apply.