I think it is horrifyingly common, actually.
Quite a few people turn up here with a new diagnosis of T2 and pre-existing complications like neuropathy, suggesting that their blood glucose has been out of wack for a prolonged length of time.
Plus the fact we can have 'normal' or 'pre diabetic' HbA1cs for years (it is an average reading of blood glucose), while our blood glucose shoots high enough to cause damage, then drops low enough for us to feel dreadful, all the while that HbA1c remains 'normal'.
Thank heavens your T2 has been spotted now!