Cats can eat sweets, but it's recommended to give them as little as possible or none at all. This is because cats don't rely on carbohydrates for energy; they primarily use protein. This is why it's important to buy cat food with a high meat content. Feeding them large amounts of sweets can burden their digestive system, causing gastrointestinal upset in some cats, and in severe cases, vomiting and diarrhea. 
Reasons why it's not recommended to feed cats sweets:
1. Increased risk of diabetes. Cats lack a certain enzyme that breaks down sugars. Therefore, after consuming large amounts of sugary food, they cannot convert the sugars into other nutrients for absorption, causing them to accumulate in their bodies. When the sugar buildup reaches a certain level, it increases the workload on the cat's pancreas, significantly increasing the risk of developing diabetes.
2. Cats are not sensitive to sweetness and cannot taste it, so they are prone to consuming too much sugar. This not only makes cats more prone to obesity, but also increases the burden on their kidneys, which can easily lead to kidney disease and symptoms of kidney failure.
3. There are many types of sweets, including cream and chocolate. Cream can easily cause cats to suffer from pancreatitis, fatty liver, and other diseases. In addition, theobromine and caffeine in chocolate can cause cats to have a poisoning reaction, so it is best not to feed cats sweets.
