Joined an unwelcome but not unexpected club this week

Kitty and I actually were able to come off of it some time ago. Through eating better and slashing soft drinks. About all I drink now is probably 95% water, a little coffee and a VERY small amount of soft drink if we eat out...but I usually drink water there. ....and of course the occasional shot of Fireball. But we used to drink soft drinks a good bit. I've actually lost the taste for them now a lot. We don't even keep any at home anymore.
Wife is borderline diabetic, she is on Metfomin. She drinks Diet Dr. Pepper like a drunken sailor. She claims it is not bad for her. Is she pulling my leg!????