In order to feel sweet, you need TAS1R2 and TAS1R3 proteins. It is thanks to them that our brain understands: “Before us is the source of energy.” In cats, this mechanism is “broken”, due to which they do not feel the sweet taste of food.
The TAS1R2 gene, which is responsible for half the receptor of sweet taste, is damaged in the cat family. This failure occurred for a very long time: even a common ancestor of tigers, lions and domestic cats. Therefore, they do not react to sweet food.

But why did the evolution have “turned off” the sweet taste to all cats? The fact is that their diet has always been the basis of their diet, and it does not have glucose and fructose. Therefore, gradually the ability to recognize the sweet taste in these animals disappeared.