Unwittingly found out dumping is no joke!
I like London Fog (Earl Grey tea) latte from Starbucks. I ALWAYS go inside so I can watch that they use the SF Vanilla syrup (usually SF syrups have a black pump). I also get it made with fat free milk.
I have late dumping (reactive hypoglycemia) and will not risk getting a latte through the drive up. However, I do get unsweetened green ice tea thorough the drive up. One sip and you can tell if it is unsweetened or not - but the lattes taste the same - unfortunately.
I had a RH episode about 4 years ago with Starbucks using the full sugar corn syrup and won't take that risk again.
I agree that making your drink at home is good, too. I order Starbucks vanilla sugar free syrup online, usually when there is a sale or free shipping and make my latte at home.
Best wishes, Penny