Not an expert, but as far as I am aware, your blood sugar level will fluctuate after eating a meal....in much the same way as a non diabetic?
Don't know if you are on a pump, or are asking becasue you ar einterested in them. I have mine set, at teh moment, that my acceptable range is between 6 and 8 mmol/l. I know that this is too high, and I am in teh process of bringing this down, so that my ultimate aim is to be between 4 and 6 mmol/l. Now, do I always fall into the band..no. I have one of those pumps with a wizard, that advises you on what bolus insulin to take...you have to work out the basal rate yourself. There is a post meal setting, where it "allows your bg to raise by 2 units after a meal. This only has any effect if you test. So, say, it is 1 hour after lunch, and I test my blood, and my reading is 9 mmol/l..then, on current settings, this is OK...but if I test again another later, and I am still 9, the pump will advise me that I should take a bolus to bring my BG back into my desired range.
This doesn't look very good I know, and that is becasue of my settings!
Another thing to look at is the advice Drs give people who think that they may be diabetic. I can't remember exactly what the numbers are, but after a meal, their BG can get as high as (about!!!) 7, and this is still normal.I don't think that anyones bg, diabetic o not, stays within a small range of readings.
Sorry, not an expert, but hope that helped.