Why when I drink soda I feel dizzy?

See below. Sugar in soda is absorbed in the small intestine Insulin id released result on low glucose.
Beats me. If you are drinking sugared drinks, you could have reactive hypoglycemia, where the sugar load causes your body to make more Insulin and this lowers your blood sugar too much causing dizziness. This can even happen with some "diet" drinks where your body is tricked by sweet taste into making insulin, with the same result. Stop drinking soda, see your doctor for evaluation if it continues.