We may try that. My wife has the problem that she was given sugared tea when she was a baby and now she simply cannot drink water: soda, syrup, or the best she can manage is making 5 liter tea ($deity bless whichever company still makes huge steel kettles, 4l and 5l ones) with 5 tablespoons of sugar. While 48 kcal per liter is not too bad, about 150-200 kcal drunk a day, I am afraid for her insulin and try to find alternatives. White tea may be one, thanks.

Next step would be coffe without sugar.

Or finding an artificial sweetener that does not taste as bad as sacharine or aspartame.