There is quite a plethora of information on the web, too much to allow me to succinctly put here. Commonly the evidence relies on more comprehensive information.
So, yes caffeine affects diabetes and sugar. Probably due to reduced insulin sensitivity.
Comprehensive information would be 1) How much caffeine per drink, 2) What dairy do you use in the drink, 3) What do you use to sweeten the drink?
More advice May be forthcoming.