Even if glycerine has as many carbs as sugar, which I doubt it does, then a tsp would contain 4g of carbs. A tsp contains about 98 drops.

So... how much of this are you using? Stevia is very potent, at least 200x sweeter than sugar in it's extracted form.

Doing the math, then 3 drops is 3/98 of a tsp of sugar worth of carbs. I'm not really sure that would even register.