At first, when I fasted or ate very low cal (LC, of course) my BG rose higher than I usually saw (my spikes at that point were about 115 mg/dl. I saw as high as 130). I found some comments, I think on Blood Sugar 101, about the liver releasing glycogen in an effort to keep the body at what it considered 'stabilized'. Think of it as Dawn Phenomenon happening during the day.

I expected it and rode it out. Over a very few days, the BG rises gradually decreased. My DP pleasantly stopped at the same time. I think my liver and pancreas needed time to get the message, 'there's a new game in town'.

These days, on no meds, I rarely go over 100 after eating. When not eating I gracefully slide into the 70s.

Of course, your DH could have a completely different metabolism and under-riding issues. Meaning YMMV.