My sister is complaining how her vision is becoming a bit blurry even though she does wear glasses and haven"t worn any in a while. She also say thats she gets numb in her feet sometimes as well. Are these minimal signs of diabeties or is it caused by something else.

I am assumingby the delay in ths post that she has since your post been checked out?

but if not.. blurred visison and tingling can be indicative of a host of other conditions. what we ahve to look our for are the typical signs of diabetes. weight loss, unquenchable thirst, wounds that dont heal quickly. neuropathy in the feet can be a sign of anything, Including diabetes insipidus, neurological damage, mini strokes (TIA) etc.
so unless pattern of elevated BGs can be established one will never know without an exam.
get a glucose meter and strips( get the one that si inexpensive to do) and do athree step stet. One in teh morning after a 10 hour fast, one two hours after she ahs eaten a meal and two random duringteh day and see where her numbers fall. I fthey are above 140 fasting,, then there is a good possibiloity that she could be borderline, if shes higher than that during teh day then its an even bigger indication. However if she falls ina " normal range" then there is something else amiss.

I would suggest that she get checked out for everything and anything. It may not be diabetes, but it sounds like she has something going on that shouldn't be. Good luck to her. Let us know how she makes out.