How fast do foods affect your blood sugar?

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I’m a type one diabetic, and having a low blood sugar is one of the worst feelings in the world. I’ve started wondering the science about how things affect you when you do have a low blood sugar. For example, how quickly after drinking juice does your blood sugar start to go up? For me, while I’m stiting there and waiting while my body dumps adrenaline into my system, feels like forever!

In: Biology

6 Answers

Anonymous 0 Comments

Each food item has a [Glycemic index]( Pure glucose is defined to be 100, and everything else is less than it, and it is precisely a measure of how fast it elevates your blood sugar.

Also an important note, GI on its own doesn’t have a direct impact on how healthy a food is. For example, ice cream is considered low GI because all the fat in it slows your digestion, which makes it absorb into your blood slower than whole grain bread.

Anonymous 0 Comments

At the hospital I work at, when we are treating low blood sugar, we give juice and then recheck BG level in 15 minutes. So, juice will affect your blood sugar in 10-15 minutes.

The glucose gel will get absorbed through the lining of your mouth, so it’s even faster.

Anonymous 0 Comments

I guess almost instant? Like not as fast as putting honey or some sugar gels on your gums, but still fast. Ofc its dependent on situation since if your blood sugar is going down very fast it takes more sugar/time to get it to turn around.

And cant agree more on the last part. Even thought I know its gonna get up I still sometimes take more or make bread or smthng before the feeling fades only to put more insulin, bcuz I was going to be fine with the first one😅

Anonymous 0 Comments

Fast food breads & buns spike the carbs. It raises my blood sugar level almost immediately. I hardly ever eat fast food anymore because of that. Ask for “Protein Style” at In-N-Out Burger and they’ll replace the bun with a lettuce wrap. Or order The Flying Dutchman and you get the double-double between onion slices, no bun

Anonymous 0 Comments

I’m also a type 1, I can tolerate extremes though and I don’t really feel bad until I hit around 40 or less. But anyway, liquids are the best and take around 10-15 minutes at most to feel an improvement. I just throw some sugar in a bottle of water and keep it by the bed whenever my dexcom starts screaming at night, it triggers at <60

Since I have a constant monitor that takes readings every few minutes I can track it in real time. Despite drinking sugar and feeling better my actual number doesnt go up right away, it takes another 10 minutes before I can see it. It’s kinda odd, I would expect it to go up alongside feeling better but it has a delay.

Anonymous 0 Comments

Fruit juices don’t raise blood glucose levels as well as pure glucose does. Fruit juices do have glucose in them but they have a lot more fructose which is not known to raise blood glucose well.

Actually, here’s an article that explains this all better:


I’m not saying fruit juice doesn’t help diabetics, but for some, pure glucose may work better and faster. You need 15g of carbs/glucose to increase blood glucose levels, check levels after 15 minutes and repeat if needed with another 15g of glucose until blood sugar levels start increasing.