I'm not very familiar with the Starbucks menu, but I would venture that any coffee drink with just cream and artificial sweeteners would be ok
Just no sweetened whipped cream, chocolate syrup or real sugar sweetened syrups, that kind of stuff.
If you find caffeine is making your blood sugar drop and causing hunger/wooziness, you may want to go the decaf route. Atkins was not a big caffeine fan, and forbid it in Induction (maybe throughout weight loss? I am not sure.) I myself drink regular coffee with heavy cream and a single packet of Equal in the morning... and don't feel I suffer any ill effects from it