The amount of carbohydrates in a can of Coke depends on the type of Coke drink and the size of the can.
A standard 375ml can of Coca-Cola Classic contains 39.8 grams of carbohydrates, but the 375ml can of Coca-Cola with Stevia contains less than half that amount, with 18.8 grams of carbohydrates. A 375ml can of Coca-Cola Vanilla also contains 41.3 grams of carbohydrates.
The 375ml can of Diet Coke also contains a smaller amount of carbohydrates with 0.38 grams, the same amount of carbohydrates can also be found in a 375ml can of Coke Zero.
The source of carbohydrates in Coca-Cola is cane sugar.