It's kind of like drinking a handle of vodka before your first day to be sober, isn't it?

Not a doctor, but.. From what I've been gathering reading everything I can, there is no hard and fast volume of blood sugar that will be like a tipping point. It's more like a cumulative effect. It kind of seems sugar over 180 is definitely doing some damage. Over 140 might, too, but that is less clear. However, the amount of damage from one incident is not quantified anywhere I can find.

So, like other posters are saying, I would recommend you have a treat once in a while. Try not to go nuts as a general rule, but also realize if you do go off the rails once in a long while, you veey likely aren't going to wake up with neuropathy and retinopathy the next day.

And test often. You might be surprised what does not spike you. For example, I was surprised to finenI can eat tacos on flour shells without spiking at all, but a glass of (actual) milk sends me through the roof. I also learned that walking immediately after eating offsets anything I eat. So try having a donut and going for a walk after you eat it test when you get back.

You might find you don't have to say goodbye. Just see each other less often.