Carbohydrates are sugars and starches.
Sugars are also called simple carbohydrates while starches are also known as complex carbohydrates. Starches are simply many sugar molecules joined together into one very large molecule. Starches are broken down into their constituent sugars molecules in our mouths and intestines. The sugar molecules are then absorbed by the intestine into the blood stream. In response to the absorbed sugar in the blood, our pancreas secretes insulin into the blood.