Lows, treatments and timing

I’m learning a lot with my new venture into CGM. Some questions about lows. What do you consider a low (enough to treat)? Do you use a number or a trend or symptoms? What do you use to treat? And how much do you usually use? How long do you wait with no change before re-treating? Is it different at night vs day, or close to meals vs after meals? I have so many questions because it is different now that I’m using CGM. And because my control is tighter (A1c down from 8.6 to 6.6) I’m having more lows.


Hey, congrats on the tighter control!

It totally depends on the context for me on the majority of your questions. If I’m already low (below 65), and I’m not waiting for a meal to kick in that I recently ate, then I’ll treat the low. The amount of carbs totally depends on how much IOB I have, how low I am, how quickly I’m dropping, and tbh how shaky I’m feeling. If I have lots of IOB, am dropping quickly, and I’m feeling the low a lot then I’ll treat more aggressively with up to around 15g or more if necessary.

Normally though I can use a few skittles (1 skittle roughly is 1g carb) to correct a mild low when I don’t have a bunch of the above factors (when I’m not dropping quickly, when I don’t have a lot of IOB, when I don’t feel like I’m dropping quickly).

I also like using swedish fish and sour patch kids snack packets or gatorade for my lows :smiley: Or whatever is in reach that will kick my number up.

I’ll wait like 5 min-10min to test my blood sugar again, and if I haven’t come up I’ll think about having some more carbs. Totally depends on how low I am though!

I think you’ll end up getting a range for how people like to treat their lows. I think it’s all about getting yourself out of danger while also trying to avoid the spike after


I use a number + trend. Our son can only tell us occasionally if he’s feeling low.

1 Like

This is the kind of thing our endos see a lot, which is why they always wag their fingers and say “Don’t let your A1C go below 8 or you’ll have too many lows.” It’s a valid concern – they’re worried about us becoming hypo unaware – but I’m not convinced the two have to go hand-in-hand (although they often do – unfortunately I’ve had my lowest A1c’s after I’ve been having too many lows). The trick with aiming for tighter control is to intervene sooner – which is where your CGM comes in.

My low alert is set to 3.8 (68) – I’m rarely symptomatic at that point unless I’m dropping really fast, but it gives me time to bump myself up before I would have symptoms. If you find you’re having too many lows, or you go low and stay there despite treatment, you could set your low alert higher, so you’d be treating at maybe 90, and see how that works out for you.

As for how much to treat with, when to retreat, etc., @LarissaW took the words right out of my mouth.


I think as you get down into the 5’s and 6’s in your A1c you need to be extra vigilant to ensure your basal rate is set appropriately. When my son has managed an A1c of 6.1, he also bet his endo that he could lower the number and time in low on his CGM. His endo says this was not possible, but by being attentive and having his basal really dialed in, he managed that feat. So if your basal is finely tuned and you are paying attention to the CGM or using aggressive alerts, I think you can reduce the lows.


I always have glucose tabs with me, and I have my low alert set to 85. When the alert happens, I look at the CGM graph to see whether it is rising (do nothing), steady (do nothing and wait for another possible alert after 20 minutes), or falling. If it is falling, I take some glucose to turn my BG back towards the good range. How much glucose? That depends on how much insulin I have in me (“active insulin” or “IOB insulin on board”), and it depends on how fast I’m falling. My goal is to use up any extra insulin and move my BG back to 100. In my case, 1 glucose tab raises my BG about 10 mg/dL, and 1 glucose tab counteracts about 1u of IOB. But it’s complicated depending on how much digestion is still ahead of me.

Simple example. I ate some carbs 2 hours ago, my BG has fallen to 85, trending down at a medium speed (Dexcom birdbeak angled down, not straight down or double down) and I have 2u IOB. Since it was just carbs, the digestion is mostly done, so I don’t need those 2u of insulin that are still in my system. I’ll take 3 glucose tabs, 2 for the IOB and one to raise 85 to 95.

Another example. I ate pizza 2 hours ago, my BG has fallen to 85 with the arrow straight down, and I have 6u IOB. Pizza is slow to digest, so there’s lots more digestion ahead that will tend to raise my BG. But I’m falling fast and it could be hours before the remaining pizza digestion starts to raise my BG. So I’ll take 6 carb tablets to raise my BG to a safe level, counteract the “momentum” of the rapidly dropping BG, and reduce the amount of remaining IOB so I won’t crash. And I’ll look again in about 20 minutes to see if I need more glucose, or if I took too much. If I’ve already bounced back up to 100, maybe I’ll put on an extended bolus of 3u over 3 hours to help soak up the rest of the pizza as it digests.

All of these strategies are kind of wishy-washy intuitive rather than scientific. And our bodies are all different, so you have to find out what dosing works right for you. In particular, there’s no reason to think that 1 glucose tab will raise your BG 10 mg/dL, but it’s easy to find out by eating one when you are fasting, level, and sedentary to see what happens to the CGM graph over the next hour.

Let me finish with the simple advice, because the details can be overwhelming when you’re in the process of figuring out how your body works.

  1. If your BG is too high, you need more insulin.

  2. If your BG is too low, you need carbs. Glucose tabs are the fastest.

  3. Use frequent small doses of insulin and carbs to keep turning the CGM graph in a good direction. One exception: take a large dose of glucose for self rescue if your CGM graph is plummeting towards a serious low.


@bkh - Thanks for the reply. Those examples are really helpful, and your “simple” advice is very good. The frequent small doses of insulin and carbs is especially helpful. I understand not to take too much insulin too frequently to keep from stacking it, but I tended to think small doses of carbs wasn’t a “real” treatment for low BG but instead “cheating.” Now I see how it can keep me in the lower range without being too high or too low.

1 Like

In my view, that was more of a concern back before CGM, when stacking insulin meant you could crash low with no warning. Since my CGM is trustworthy, stacking insulin isn’t dangerous for me, it is simply another tool to help correct a stubborn high. If I take too much insulin I’ll see it in the CGM graph when it starts to plummet, and even if I don’t notice it, the CGM will alert me so I can correct it with glucose. Of course I try to give myself the right dose of insulin every time, but in any case I can always steer it in a good direction when my prediction turns out wrong.


How quickly do dextrose tablets, or smarties begin to work to raise blood sugar? Do I measure 15 minutes after taking the dextrose?

How quickly does the 3 glucose tabs begin to work? Do you measure in 15 minutes? I don’t have a CGM. Thanks!

On an empty stomach with water they are really fast; start to work within minutes. After a heavy meal with lots of fat and protein, the glucose will be a bit slower to act but it’s still the fastest carb that can be eaten.

It depends. If you think you may be in trouble, measuring after 15 minutes should show a significant improvement, and if it doesn’t, another dose of glucose would help. In my case since I use CGM, I’ll glance at the CGM after 15 minutes but it would just barely show the trend starting to change; I’ll get a better idea after an additional 15 minutes passes. Fingerstick measurements are much faster than CGM at showing trend changes.


The CGM is about a 15 or 20 minute delay, IIRC.

I have this, perhaps irrational, fear and panic about a low that wouldn’t come up. It’s never happened. However, that’s why I tend to not overbolus. I’ve read some of the suggestions, and it all makes sense. It’s faster to correct a low BG. It’s slower to correct a high BG - because insulin takes a longer time to become effective. That’s why I’m trying to get a better understanding of how quickly dextrose can start to help raise BG. I hope this makes sense.


Well, here’s a story from when I was probably 2 years into diabetes, on MDI and no CGM. I took my daily Lantus dose as usual in the evening, after dinner. After 20 minutes I was feeling quite low. I took 3 glucose. After another 15 minutes I was feeling terrible, so I measured and was in the low 40s and presumably plummeting. I ate 8 glucose tablets which tasted metallic and not at all sweet (this turns out to be a common occurrence with very low BG) based on my rule of thumb that 1 glucose raises my BG 10 mg/dL, plus 2 extras because this was a self-rescue situation. After another 10 minutes I was feeling better, but needed more glucose plus slow carbs for several hours. I concluded that I must have taken Novolog when I intended to take Lantus. Anyway, I’m convinced that even in a rescue situation, glucose tablets are fast enough for me. Beyond that, there’s the glucagon kit.

In my experience, glucose tablets have always easily solved an insulin overdose, even with complex meals. It might not be as simple for someone who suffers from delayed-emptying of the stomach into the little intestine, but I don’t have that issue.

You could try an experiment. Take a small overdose of insulin with a meal, one that might send you into the 60s, and then when you start to go low take some glucose and watch what happens. If your BG comes right back up, that may give you more confidence.

That varies from person to person, and the G6 is supposedly faster. But with my G5 I can start to see a bend in the line about 15 minutes after taking glucose.


I’ve very rarely been low. It’s good to know how fast dextrose can work.
The best I can recall, from my experience may have been that dextrose can raise as fast as 15 minutes.

I have found a really different experience with glucose (4gm) tablets. I don’t see ANY significant rise until about 30 minutes. but by 30 minutes they have reached their peak; meaning, they don’t continue raising your BG. pretty reliable for moderate lows (50s). for super scary lows (30s) I take apple juice immediately. this works immediately and within 15 minutes I begin climbing up from shaky hell. however, I am careful not to overdo it bc BG continues to rise even after that 15 minutes. I give it a decent 1/2 hour before testing again. I would rather be a little higher than my target range than b in my 30s though.

Eric turned me on to TRANSCEND gel shots. they have about 17gms glucose and work INSTANTLY. but, like many other forms of glucose, they will continue raising your BG for a while after your sugars have reached back to your target range. but, as always, YDMV.

During the past weel, I’ve experienced BG’s in the 60’s more than once. I felt no symptoms! In one case, after I corrected and the BG was 85, I felt ravenous. Although - this may be more a function of the time of day. Often, between 4-6 pm, I can become SO SOOOOO… hungry that i feel like a crazed person. Does anyone else feel this way?