well, there's two things

one, is it contains sugar, about maybe equal to 1/5th of a teaspoon in every cup, maybe a little more, it is caramels though, so it's something between sugar and starch

the other thing is that paraxanthine, the main active metabolic byproduct of caffeine metabolism by the liver actually stimulates the conversion of fats to sugar, so it definitely does raise blood sugar levels, just not so much as actual sugars, but not zero, as you can see considering the two points, probably a cup of coffee is equal in blood sugar rise to 2tsp of sugar, and then you put another tsp on top...