I'm not sure about blood sugar levels, but I have heard that all acid reducing (not just Prevacid) meds have the potential to cause lower levels of B vitamins (and not sure if it's all B's, but definitely B12)...something to do with lack of acid of stomach and intrinsic factor, etc...( I don't know all the details...) Somebody recommended to me that I take sublingual B12- the methylcobalamin form- since I was taking a PPI. NOW Foods makes a sublingual B12 that is cherry flavored.