Humans should be able to make enough Taurine to get by normally.

But diabetics seem to have problems relating to low taurine specifically. Since it is made in the pancreas, there may be some link there.

Also extra taurine can be helpful for sluggish gallbladders, and to help reduce gall stones.

Cats are one of the few mammals who cannot synthesize taurine for themselves. They are dependent on the rodents they eat for it. This is why taurine is added to commerical cat foods.
I give extra taurine to my cats, mixed into their food, when I give "human" type food proteins to them. (Tuna in oil, for example). I have found that giving table food minus seasonings, leads to better health for them. And Oreo with her mast cell cancer does very well on Tuna in oil. (with Taurine added by me). The goal according to the Vet is to keep her from losing weight, and the Tuna does this very well. She also gets plenty of commerical cat foods too, including a new grain free kibble by Blue Buffalo.

I can't see taurine being a problem for humans, as a supplement. I've used it myself for gall bladder issues now and then, but I don't take it all the time.

Taurine and inositol are recommended supplements in some papers for diabetics.