Hi, Natalie -
There are 3 unrelated components to the time it takes for a recovery (or start of a recovery) to be reflected in your Dex unit.
1) the amount of time it takes for your body to digest and distribute what you have ingested
2) the amount of time it takes for that change to be reflected in the interstitial fluid as measured by the sensor
3) the amount of time for the data point to be transmitted to the DexCom receiver
The most important is the first one (because that is how quickly you are actually recovering). Obviously, you wouldn't blame your DexCom system if you were trying to raise your blood sugar by eating alfalfa sprouts, but so many people drink orange juice or, even worse, (as I used to do) juice boxes with high fructose corn syrup. Fructose, which is in both of these examples, is digested a bit differently and more slowly than other things that you can use. I just started buying Welch's white grape juice in 10 oz bottles. "Grape sugar" is glucose and this is a great tasting fast way to get usable sugar into your system. I get white because my wife would not appreciate a purple bedspread or carpeting if I am so low I drop the bottle.
The #2 item is one of the main reasons I chose DexCom over the Medtronic system. The sensor tube length is shorter and so it responds more quickly. They also appear to have done a better job of prediction in their software. (I am 7+). I found, as I evaluated the two side-by-side, that the rapid changes were MORE accurately reflected by the DexCom system---at least for me.
The #3 item is just what portion of the 5 minute reporting period your uptick is in, between updates to the receiver. Since it updates every 5 minutes, there is a 5 minute variation on when your receiver will know when things have started to climb.
At any rate, yes, it is not instantaneous, but the most important thing is to ingest something that, as close as possible, is.
By the way, it is very natural to over-compensate when experiencing a low.
a) part of the adrenal reaction is to become voraciously hungry
b) we don't see an instantaneous change and that can be worrisome
c) we want to get back to normal quickly, and that means "flooding the market".
I always take insulin when I am eat - even if it is for hypoglycemic compensation. The insulin won't hit until well after the sugar does and will help to ensure that I don't go TOO high.
Sorry for the long harangue for my first tudiabes post. Good luck, Natalie.