What Gerri said is spot on.
My experience: I'm T1, on a pump, Dexcom CGM, and have been on a Bernstein diet going on 2 years. The majority of my PPs are around 110-130, starting with a flat trend of 80ish before a meal. Trying to hit a completely flat day is really tough and requires a lot of micro boluses (10-14 a day) and small glucose additions. It's pretty much one bolus every 1.5 hours that I'm awake and some of those are extended over 2-4 hours (think R insulin).
So, when my body switched over to getting glucose from protein/fat I noticed my PPs changed to a 3-4 hour stretch as opposed to the old 2 hour trend. Also, only large boluses will effect my PPs. Meaning if I go up to 120, 20 minutes (to 3 hours) post meal, it will take about 5u of insulin to bring me back down. What a fascinating digestive system!
So, can I hit 83 1 hour after a meal? Yes, I call it flatlining. Does it happen all the time? No, not by any means! Plus, it requires a lot of effort to do so depending on regularity of food and dose timing.
Still, it's a great standard to try to reach and my BGs have never (in 27 years), been better.