If you add sugar to your tea, then the only thing you are guaranteed to achieve is your tea will become somewhat sweeter. Everything else is speculation.
According to statistics for the 19th century: 100% of people who drank tea with sugar died. 100% of people who drank tea without sugar died. 100% of people who drank sugar without tea died. The same statistics for all past centuries. Summing up the results of the XX century is not over yet, especially for the XXI.