I have 3 x tea and 2 x coffee each day, both with milk, no sweetening, use skim milk for tea, full cream for coffee, makes NO difference to levels.
But a bought latte medium size can hold my sugar level steady for at least an hour even if late for next meal, have tested this quite regularly and that is without any food. I have full milk then too 😀

20+ years and necer had caffeine effect my glucose levels
What the caffeine contains kike sugar is more likely to effect levels if not dosed for correctly.

Personaly i like black coffee

I think my most honest answer is...it depends on the day and sometimes what time of day...for me...I love sumatra coffee..so sometimes...I just have it...I use stevia..absolutely not the same as suigar...but ive learned to be okay with it...and heavy cream...which is why I llimit how much coffee I drink anymore

Caffeine doesn't seem to have a unified position among doctors and researchers. some says its ok, some say it's bad. All will say it's bad in the form of sodas, whether diet or worse, regular. Tea and coffee seem to be ok, as long as there isn't too much sugar, cream and add-ons to introduce sugar and carbs.

I agree I do not add sweetener to tea or coffee but if my numbers are low I have a frothy coffee, the Nescafe sachets do have some added sugar but these I limit, just a treat.

We mainly drink tea 🫖

I try to stop any drinks with caffeine by 5 to 6pm after then just cool water.