To me it is any unanticipated surge in blood sugar that takes me out of my target range. So really, I guess it depends. I would generally consider anything over 140 mg/dl as a "spike."
I personally think "spike" is a very poor term for how I view *my* worst bg variations.
If I bolus for a meal before I eat it, I sometimes go hypo after a meal. That hypo after a meal sometimes is a real bugaboo... oh I hate it. I hate it so much. So I think my most dangerous spike is when my bg spikes downward in such a situation to below 50. That's my worst fear.
If I don't bolus at all, my bg doesn't spike... it just goes up and up and up.
Almost all of my most vexing bg problems have nothing to do with meals but have to do with dawn phenomena or other non-food things that drive my bg up and up... with no down until I take insulin and (surprisingly!) have something to eat too. Just for comparison: I can wake up at say 70 or 80, not eat anything for 3 hours, and find my bg at 350.
I really hate that feeling, too. The one that also ticks me off is going to bed with a sugar of 93 and waking up with it at 250. I've heard that there can be a number of reasons for this, but none of them really apply to me, so I struggle to figure out what I can do differently.
But the up-down-up-down thing is awful.
Oh, and my definition of a spike is over 120.
Over 140 is a spike for me. I shoot for around 80-120 and will correct for anything over 140.
The software for my meter is capable of making a line graph of my readings over time frames I can set. For me a spike is anything that looks like just that . . . a "spike". There are some dips and "speed bumps" along the way but a spike for me is being significantly off target . . . over 160. Being between 140-160 is more like a speed bump and as long as my a1c hovers in the 5.8-6.2 range I'm ok with that.
for me, I am happy to stay below 160-170 after a meal. Staying below 100 all of the time sometimes isn't best for me, since I can go unexpectedly low sometimes.
I consider anything over 140 a spike that I correct for. But I agree the term is a bit hazy. It implies that a spike is the high point and after that it's headed down. So a 140 2 hours after a meal is technically a spike, but I wouldn't correct because I still have enough insulin on board to bring it down. But if I have 140 another time with no IOB I will correct. On the other hand a 140 anytime could mean it's going up and when I check it a bit later will be 160 or even more and then I correct. I guess that's why people like CGMs - because they tell you if it is on its way back down or trending up more.
The only time I correct below 140 is if I'm due for a meal soon. Then I correct or bolus for my meal and add a correction.
I don't understand considering anything above 100 being considered a spike as I consider that a pretty much perfect blood sugar! I do know some people correct at 120.
I agree - for me it's a nasty pointy peak with a quick-ish rise and fall. They make me feel awful. I correct anything over 110 if I have no IOB, and get pretty po'd if my ping says I still have too much IOB to add more.