In the 1970s Gary Beauchamp, Ph.D. , now director of the Monell Chemical Senses Center, demonstrated that lions, tigers, cheetahs and house cats have no preference for sweet tasting water. The simple experiment at the Philadelphia Zoo allowed each species of cat the same access to water with sugar and unsweetened water. The cats showed no preference for sweets.
Dr. Leslie Stein at the Monell Chemical Senses Center determined that all cat species have a broken gene (pseudogene) in their sweet taste receptor. The receptor requires two genes to act in coordination to produce the sweet taste response in the brain that is common in most mammals. Cats have one gene that does not respond to sweet tastes so the sweet taste response is not ever sensed.
Cat owners have noted that their pets enjoy some foods that are sweet. The researchers maintain that the cats are responding to some other taste than sugar in those foods. The most probable taste the cats are responding to is salt. Texture could also be a factor in house cats preference for some sweet foods.
The broken gene may be an evolutionary adaptation that acts as a protection or could have occurred as the result of the lack of sweet foods available to ancient cat ancestors that produced the demise of reaction in one part of the sweet taste receptor.
The video is available here.