Impossibly-volatile and seemingly-random variations in C/I ratios

Greetings all,
I realise i have a few unanswered points in my other thread, i’ll get to those when i can. In the meantime, i’m trying to manage wayward BG excursions. Is it just me, or do others find their C/I ratio is sometimes fairly reliably (say) 1u/15g at a certain time of day, and then, suddenly, without warning or external influence (no change in stress, exercise, sleep, anything), it jumps to (say) 1u/3g ?

A case in point, this afternoon. I was nice and stable from midday to around 3pm, after a 28g carb lunch, upon which i decided to eat a nectarine. it weighed in at 165g, so i figured less the stone, and 11% carb, this was around 16g of carb. I should need 1unit. So i injected 1u and ate it… and then i rose sharply, so i injected more, i rose further, i injected further, i rose futher, i injected further, i rose futher, i injected still further. i ended taking with 5u, for 16g, so my ratio has moved, without any notice or external influence, from 1u/15g to 1u/3g. That’s not just a 10-20% shift, that’s a 400% shift. How the heck was i meant to know this was about to happen? And how is managing to stay in-range (or nearly in-range) even remotely possible when the goalposts shift around this wildly ?

The only external influence i can think of is a coffee (no sugar) i took around 3:30pm, with a splash of milk (surely no more than 2-3g of carb in the milk). I drink 2 or 3 coffees per day and don’t usually notice them having much effect on BG.

What is going on?


Did you prebolus the nectarine? I am willing to bet if you had waited until the CGM trend was aggressively downward, that you wouldn’t have peaked so high.


honestly, when I see spikes like this, it is often a sign that we could increase underlying basal just a touch. But… we are on a pump, where it’s easy to increase basal for a day or two. We hardly ever prebolus by very much. At most, maybe 0.2 or 0.3 units to get some insulin in there to prevent liver dumping of glucose, and then the rest bolused as he starts eating. If we prebolus the entire amount, Samson will go low and then high an hour or two after eating.

If its any consolation, I spiked 1hr after finishing lunch from 97 to 167. No rhyme or reason. Same meal I have all the time. no stress, good nights sleep, regular exercise, same ICR….its called Diabetes. sometimes this crap happens and the best we can do is to do exactly what you did: correct with more insulin.

Please, I hope that you feel better and that your sugars come bk into range! :grin: :heart:


I thought I would share this with you bc I wanted you to know that you are not alone with this annoyance:

As I mentioned, I spiked after lunch. At first I spiked to 156, and I gave myself an appropriate correction dosage. an hour later, my BG not only did not come down, but it went higher (177) So I gave myself an IM shot in my thigh, and only now, one hour later, my sugars r beginning to come down (128 BG with CGM reading arrow trending down). Ah, there’s hope…now I just hope I don’t crash and have to put up with the Yo-Yo Effect :crazy_face: :grimacing: :pray:

This happens to me for sure. I eat the same breakfast every morning. The other day I ate and saw that I was spiking quickly and bolused five extra units off the bat. I was sure I’d end up going low, but my blood sugar peaked and came down and landed in range. The next two days, all was well and my usual bolus worked perfectly. Today, I didn’t spike as high but have plateaued at a high level for the past two hours after eating and have taken two and then three units over those two hours. Hopefully I’ll come back down into range without going low. I do pre-bolus for breakfast, including this morning, so pre-blousing is not the issue.

It would be interesting to know if they have done any studies on this, but I really doubt that a working pancreas produces the same amount of insulin for the same meal, just as I seriously doubt it produces a stable baseline all day like the flat basal insulins out there. I think these are just the best tools we have at the moment, but they’re only a starting point. A strategy like “sugar surfing” would view using one unit one time and five units another as no big deal.


That spike from a nectarine is puzzling. When similar unexplained spikes happen to me 2-3 hours after a meal (lunch in your case), first I try to rule out a high fat lunch with slow digestion. Maybe the nectarine somehow triggered your gut to finish digesting your lunch? But it is also possible that your basal or your bolus timing needs to be adjusted. Trial and error might be the best strategy.


No, and you’re probably right. I must learn to pre-bolus as it seems to be good hack. I was of the impression pre-bolus was more appropriate ahead of high-GI food. Nectarines are fairly low (40ish i think), so really didn’t expect such a reaction. And perhaps more pertinently, i had one yesterday, whereby i injected 1u immediately before eating - and no spike. So…what needed 1u yesterday, needed 5u today. Pump or not, i don’t figure how that’s a manageable situation, nor do i understand how others seem to stay in range 90%+ of the time. Are there different types of T1? Do some suffer from more movement in ratios than others? And therefore, do some sufferers really have it harder than others…? if so, it would suggest there is plenty we don’t understand about this disease.


I have been dialling down my Tresiba (basal) from 20u to 16u over the last few weeks, since i was often dropping in the afternoon on no food, so felt if anything I felt I had too much basal sloshing about, not too little…but i agree, this is symptomatic of too little basal. again, this is another variable (along with C/I ratios) that i feel moves around far too much, with a lot of seeming-randomness.

This interest me. I’ve not heard a liver-dump mentioned in this context, but in my other thread, i feel being low for a while seems to push the liver to ‘almost’ dump glucose, and will do as soon as some (exogenous) glucose hits the system…causing a frustrating spike. So you’re saying you can soften that effect by a small pre-bolus, even if already low? it feels uncomfortable to be bolusing while low…but perhaps i should dare to.

absolutely. me too, so dose splitting is essential here…typically 2/3 upfront and 1/3 an hour later, but i’m still working on that.

Hearing someone else suffer is no consolation at all - i’m sorry to hear this. to see these numbers is is painful, frustrating, and emotionally draining.

Right. But is one person’s diabetes different to that of another? You and i seem to suffer from a more violents aggressive glycemic volatility than others. So what’s the difference?

When i see i’m rising unexpectedly, I often wrestle with how much to bolus. How strong is that trend, will it peter out after a 1 or 2u correction, or will it keep ravaging higher and need 4 or 5u? All my spikes seem to be at a similar rate (c. 0.5-1mmol/5min), so it’s almost impossible to tell them apart…so i err on the side of caution and go 1 or 2u at a time…although in retrospect, with the wonderful benefit of hindsight, this is often incorrect.

It would be interesting to know if they have done any studies on this, but I really doubt that a working pancreas produces the same amount of insulin for the same meal, just as I seriously doubt it produces a stable baseline all day like the flat basal insulins out there. I think these are just the best tools we have at the moment, but they’re only a starting point. A strategy like “sugar surfing” would view using one unit one time and five units another as no big deal.

i’m sure it doesn’t. i suspect it takes into account, via the brain, all the many changing variables in this complex system that we can’t even imaging calculating the (dynamic) impact of…

really? 1u/5u feels a (unreasonably) big difference to me, for no discernible environmental change. i should probably study Ponder’s website a bit more, but i find the strategy ‘hidden’ across various blog posts over the years… not easy to pull it out and understand it. Guess i should buy the book…but it seems (from what i can tell) to just be careful micromanagement, using ratios and corrections, reacting quickly and constantly watching your CGM. perhaps i’m missing something but i don’t see anything revolutionary there.

Good point on a potentially high fat lunch…but i don’t think this was the case. It was a salad with sardines - so some Omega3 fat, but no more than usual. no carbs, just sardines, leaves, olives and tomatoes. Fat content, but no carbs to delay it. a couple of medjool dates and pieces of 85% dark chocolate and a coffee straight after, appropriately bolused.
Basal is (currently) Tresiba, so shouldn’t be time affected…pre-bolusing may well have helped. but it didn’t need it yesterday - and that’s my point! why this inconsistency and volatility in appropriate dosing, keeping everything else constant? and why do only some people seem to suffer this? it’s enough to makes me suspect there are different ‘types’ of T1.


I think that everyone is impacted by diabetes differently.

I’ve noticed people who are diagnosed at older ages (not as kids) talk about alpha cells and going high after a low.

I don’t go high after a low unless I ate too much sugar to correct. I had an instance in college where I dropped low during the night, and my aunt came to my apartment to wake me up at 5 pm the next day because I wasn’t responding to my parent’s calls/texts (no cgm at that time). I was still low, but thankfully seemed to be fine once I corrected the low. I don’t think I’ve had a seizure from a low- at least not as far as I can tell.

I don’t think I have any alpha cells left. Or if I do, they don’t seem to work the way they are supposed to work. My general impression - which may or may not be true - is that people who are diagnosed as adults are, for whatever reason, more likely to still have alpha cell functionality. It would be interesting to see if that is true.

Since insulin needs are impacted by so many things, everyone’s diabetes is going to be a bit different. Some women’s insulin needs are more impacted by their monthly hormone cycle. Some people have increased basal needs in the morning whereas others have increased needs at night.

It may be true that some people have it “easier” than others, but I think it might boil down to being able to identify more of the variables that are throwing things out of whack. If you can figure out most of the variables, then you can adjust for them. There will always be variables that we can’t figure out though. I think that is just part of living with diabetes unfortunately.


Hi John,

I have been a T1D for 48 years and have only recently begun to understand all the nuances of attempting to achieve proper time in range. First of all, diabetes can be incredibly frustrating. Just when we think that we have some sort of control over this beast, iut throws us another curveball. Just remember to be good to yourself and not beat yourself up. We strive to be perfect but that will only make your life will be miserable in trying to do so.

The first thing that I noticed from your tracing is that your insulin bolus was given at the same time that you ate the nectarine followed by a rapid spike in blood sugar. The “spike” as we call it is due to the rapid glucose of the nectarine getting into your system before your insulin bolus had time to get into your system and start working. It takes at least 20-30 minutes for rapid acting insulin to be absorbed by your body and having an effect on your blood sugar. This time of onset is different for everyone but can be seen in your curve when it starts trending down. At that point, you know that your insulin is onboard so you can eat that nectarine.

Secondly, I see that you are chasing the spike with frequent correction boluses that you have not given adequate time to take effect essentially stacking insulin. Once all those correction boluses get onboard and start working, you see an overcompensation rapid decline in blood sugar into hypoglycemia. All of us tend to get upset seeing a rapid glucose spike and want to do everything we can to bring it down immediately, but multiple correction doses in a short period of time only leads to insulin stacking and overcompensation.

So my suggestion to you would be to do your meal/snack bolus 20-30 minutes before you eat and start eating when you see the minor downtrend in your curve. Avoid stacking insulin with multiple correction doses which should not be given any sooner than every 4 hours. Duration of rapid acting insulin can be anywhere from 5-6 hours. Your insulin to carb ration may need to be adjusted but I think the timing of insulin and your meals are the issue. I would not adjust your basal insulin at all for mealtime spikes. I would also suggest viewing the short video by Dr. Steven Edelman at TCOYD.org about avoiding the spike. See if just adjusting the timing of your insulin addresses the spike.

Please let me know if this helps.


I’ve heard the alpha cell thing mentioned a few times. I suspect my alpha cells work…since i get overnight liver dumps, and often seem to spike for little reason, on no ingestion of carbs for hours. That can really only be alpha cells doing their work.

you’re lucky! you’d know about it. they’re not nice. i have had three in my 16yrs, all at night. so i’m hoping the miaomiao CGM puts paid to those episodes.

it would indeed.

There are so many variables…and what makes it all-the-harder is that their multiplier varies, seemingly random. one day a 5mi run will half my insulin needs for the rest of the day, other times no effect. one day a coffee might nudge me 3 or 4mmol higher - another day not. Identifying the variables is only half (or less!) the battle. working out their multiplier - and how it varies itself - is the tougher part.


Thanks @G6newbie. ‘Pre-bolussing’ has been suggested by a few other members and i always knew it had efficacy, i just either forgot, couldn’t wait (e.g. at restaurants), or felt it was too risky (bolussing before getting on the Tube… risking delays/problems etc), but working from home has allowed me to experiment with this and it has shown itself to be helpful.
Interestingly, i seem to observe very little difference in the ‘action time’ of different carbs. Nectarines are medium GI (low 40s), but i find they spike me just as fast as orange juice. likewise, very little difference between white (processed) vs wholegrain rice. all of which suggests that a faster acting insulin would be key to this riddle - Afrezza looks a good candidate, but not for me here in the UK.

you’re probably right here, although i thought i gave a decent time between corrections for it to start working. i expected to see at least a stop to the rise (or even a slow down) by 30-40mins, but i saw no such thing… so kept going for it. i didn’t crash after it, suggesting i really did need all 5u. for today’s, and most others, i need 1-2u. so i didn’t really understand it.

Thank you, i’ll take a look. Pre-bolussing appears to be absolutely key.


Spikes during the night can be caused by hormones, and it is called the dawn effect.

But it is not only from the release of glucagon (alpha cells). It can also from other hormones, like cortisol, epinephrine, and growth hormone (which is used for repair and regeneration, even when we are no longer “growing”).

These hormones follow a circadian rhythm. The body uses them to help us prepare for being awake. To help us “get ready for the day”. They are found in higher concentrations between 4am and 8am for most people.

(The dawn effect is sometimes confused by people with the Somogyi effect, which is a totally different thing. The Somogyi effect is just a theory, and probably not worth too much time to discuss.)


Glad that we all could help you.

I did not want to throw too much at you all at once but when you have a chance, consider actually completing a food diary for 3-5 days measuring all items that you eat and the actual carbohydrate. I use myfitnesspal and Nutritionix as my database for carb counting. It takes some effort but it will definitely help get better accuracy of your ICR. These two changes might allow you to get better control but don’t make yourself crazy. Knowing the actual amount of carbs actually helps as we tend to underestimate.

Just be good to yourself! We are not perfect. Keep me posted.


I have done this for month-long stretches in the past. it’s hard work, and does tend to show an underestimate. I measure everything each day (aside from when eating out, which is trickier) so think i have a good handle on my intake. I try to get as many (high quality, nutrient-dense, low glycemic load) calories as i can, mainly becuase i am very lean (62kg/5’10) and hence have a high metabolic rate, and also since i do a lot of aerobic exercise, so need to replace a lot of lost calories.
When measuring carbs for bolus injections, i was always told to ignore vegetables… (and lets not go there on protein just yet!) - i feel this is a poor heuristic, as typically a lot of my plate is vegetables (let’s say a steak, with roasted peppers/tomatoes/courgettes and onions, and some mixed leaves with some olive oil dressing - for example) - this would count as ‘zero carb’ (and by inference zero bolus) in a traditional diabetic carb counting regime, but the plate has plenty of carbs on it… and through these, as well as via gluconeogenesis of the protein, i will definitely get a ‘slow spike’ if i don’t inject a few units for that.
So… to cut a long story short, and i know it’s an age-old question that i’m sure has been debated heavily and varies from person to peron… but what do you and what don’t you count as carbs when you are carb counting? and how do you deal with the protein in a steak/chicken/fish portion ?


We should give you a name then, you are a “Super-Digester!” /s

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