I have treats that dont affect my sugar levels like 85% dark chocolate, a bottle of wine etc about once a week/every other week.
I'm really disciplined at the mo and turn down cake and chocolate etc even though I love it! Been Christmas when I last had some.
I treat myself properly the evening of when I had my hba1c taken. For my next one I'm buying a box of Thornton Continental, going out for beer and curry and I'll book the following day off work!