I think it's fine. My vet actually recommended a teaspoon or two of yogurt a day(I used plain super yogurt from Wegmans) as an added probiotic boost for him, since he has a testy GI system. There was organic sugar in the ingredients (you can find plan yogurt without sugar), but the vet said said he would be getting such a small amount, and that it would clear from his system so quickly that I didn't need to worry about it with his diabetes. I was skeptical, but I tested him to see how it was effecting him and she was right. It would give him a short boost to his BG (about 20-30 points) and clear completely within an hour or two. I ended up deciding to go with Fortiflora as a probiotic for him because I thought it would be more effective, but I hung on to the yogurt and used it as a quick BG booster if he was dropping a little too low for nerves at night when I wouldn't be awake, either before bed or at his 1am test. Worked perfectly for me for that purpose and gave me much better control over his BG than the dry treats or the gravy foods I was using as boosters before that because it cleared so fast.
Despite Bandit's sensitive GI system, he isn't lactose intolerant, but many cats are. If you see any runny poo, you'll want to stop.
