• Guest, the forum is undergoing some upgrades and so the usual themes will be unavailable for a few days. In the meantime, you can use the forum like normal. We'd love to know what you think about the forum! Take the 2025 Survey »

What counts as a blood sugar ‘spike’

E

EmilyMay11

Active Member
I’ve been given a blood sugar monitor to check what foods are spiking my blood sugar but so far no carbs are… unless I’m grossly underestimating what a spike is….?

Potatoes - 130g (39.5 carbs per meal)
Before meal - 5.6
After meal - 6.1

Rice - 66g (86.8 carbs per meal)
Before meal - 5.4
After meal - 7.3

Bread - 14.6g (34g carbs per meal)
Before meal - 5.8
After meal - 7.4

Now, would any of these be considered a spike?
The only thing I have found that’s spiked my sugars (unsurprisingly) is galaxy caramel when the night after I ate a whole bar I woke up to a blood sugar of 11.0.

Why aren’t carbs spiking my blood sugar?
 
Ah ok in that case you may be missing the spike. Generally speaking you need to test around the 1 hr mark to catch the spike. Of course it does vary from person to person and with different meals.
You might like to consider the free 14 day trial of a Freestyle Libre where you’ll see exactly what your blood sugar is doing all the time.
 
I started testing an hour after but it never increased more than a few points, hence why the diabetic nurse said to me only ever test 2 hours after, so I stopped the hour after testing. Just tested now, 1 hour after my dinner (chilli with 200g of potatoes) started at 4.8 and now only sitting at 5.4. I’m hoping this is the beginning of me reversing it
 
So for me my spike if it happens it' normally 3hrs after.

1hr 5.4
2hr 6.2
3.hr 7.5
4hr 5.4

Took me a lot of trial and error but worked out what foods did what to me over the years.

I can eat a whole Asda pizza to myself and wont spike above 7 although my range will run higher the next few hours.

I have say 7 chips from a chippy and I would hit a 8 or 9 later that night.

Potatoes and White Bread / Pita are my worst offenders.

As @Rachox said sign up for the Libre free trial 24/7 monitoring gives such a brilliant insight into what works and what doesn't. Plan it around an normal two weeks, with work/exercise and meals.

I ended up buying 3 months worth to fully understand my tolerances, and has made my journey so much easier, knowing I can have some of the carb based foods in moderation.
 
I’ve just applied for the free trial of the Libra 2 sensor. I’ll try eating carbs with this in and see how it goes. Thank you for letting me know about this.
 
Testing after 2 hours shows you whether your body could deal with what you put in it, which is why that's relevant when you're trying to figure out which meals are okay. A spike happens earlier, (hence the hour) so you have been missing those. But with the numbers you're seeing, over all, I think you're doing pretty good. Yay you! I hope a Libre'll give even more comforting/reassuring insight!
 
There seems to be an assumption that all meals will spike at the same time.
This is not the case - there are fast acting carbs and slow acting carbs. The fast acting carbs are the ones used by people taking insulin to treat a hypo and should cause a rise in BG within 10 minutes. Slow acting carbs or those eaten, for example with a high level of fat, can take three, four or five hours to reach their BG peak (which is why they are more challenging for people with Type 1 to time their insulin dose for).
Sorry, this is a long winded way of saying that whilst the peak may happen after 1 hour, don't be too surprised if you see a spike on your Libre graph 3 or 4 hours after eating some meals.
 
The purpose of testing is not to see "how high you go". The test is to see how well your system handled (or didn't) whatever it was you ate. On the face of it you seem to be managing.

I tend to think of a "spike" as an unexpected and disproportionate rise in BG - pastry will do that do me (although it's obvs no longer unexpected). I'm not sure that using the term "spike" is all that helpful here.

All carbs will raise your BG, and that's to be expected. Some will raise it in the first 30 mins and be gone by the hour, others will hang around for much longer. It also depends on eg what else you're eating with the carb, and whether you're having alcohol with your food - that will reduce your reading and could give you a false impression about how well you handle particular foods.

Personally I'd be a lot happier with a rise to ten and a drop back within 20 minutes than spending six hours at 8.5.
 
It’ll be handy to see if I do spike so soon after. Going to finger prick test today after my dinner. (Having curry and rice) to see the readings 60 mins, 90 mins, 2 hours, 3 hours and 4 hours after eating.

Maybe I am spiking later on.
 
I've only just stopped wearing a CGM after having one on constantly for nearly a year. I'm eating a high-fat low carb diet now, so my BG is nearly always flat, but I'd gotten to the point that the couple of recent spikes I did have (for eating something I was unaware was full of Pea Starch, and for eating something that really was too good to be true) I felt before I even thought to look on the app, suddenly feeling tired, thirsty..

Its the rapid change that affects me, and the spike itself can come and go within a half hour - there was one time my wife was testing a CGM at the same time, and we were having wildly different responses to the same food - believe that we really are all unique when it comes to this kind of thing..

One very simple thing to try though, is have your curry first, before the rice, it will slow down the absorption of carbs, so less sugar..
either way, your liver will be done within a couple of hours - there really shouldn't be any spiking later, so to speak; but honestly, there is nothing to compare to seeing for yourself what your own body is doing.. Good Luck!
 
Thank you. I might also test after 30 minutes tonight and see what the reading is if it can happen within half hour. CMG free trial in the post which I’m guessing is when I’ll see the real time results.
All trail and error which right now is so tiring and time consuming. Shame there isn’t a diet that fits all, ha.
 
It's all very overwhelming to start with, and unhelpfully; stressing about it will have it's own effect..

as an 'enthusiastic newb' to this as well, I think one big thing I've learned (learned? am learning?) is that while your body is getting used to the new normal, whatever that is for you, there will be effects that can only be happening to someone with your body, your previous situation, and your current situation... so one of the most difficult things to do is allow yourself some time to understand what is going on... even in a really rapid, disciplined regime, your body will need many months to come to a new equilibrium...
 
Ok so results are as follows after a 64g carbs dinner: -
Before dinner - 5.6
30 mins after - 8.3
60 mins after - 9.6
90 mins after - 8.7
2 hours after - 7.5

Looks like I spike 1 hour after eating (well today anyway) my question now is if my blood sugar is returning to 7.5 2 hours after than surely that’s ok? Or should I not be wanting a spike as high as 9? According to my diabetic nurse and various sources under 8.5 2 hours after a meal is what I should be aiming for. So 7.5 after 2 hours is fine??
 
It's the relationship between the first baseline reading and the reading at +2hrs that's the most informative, The standard advice is that the second reading should be no more than two points higher than the first; and not be above 7.8. Also bear in mind that all blood glucose tests like these have a certain degree of inaccuracy, so these are indicators not hard and fast values.

On that basis, your results from ttonight's meal are just about OK. If it was me, I'd want to check that meal again.

I don't worry overmuch about the levels in the first hour. I know that a small latte will take me from 5.2 to just under 10 inside 20 minutes, and I'll be back to 5.2 within 60 minutes. It just shows you that your digestive system is converting the carbs/sugars into glucose and shifting it into your blood for transit. The big question is how well your body removes it from your blood and gets it into (ideally) muscle cells.
 
This absolutely matches my experience with testing different carb intakes shortly after my T2 diagnosis.

@EmilyMay11 - Your question is very good and definitely valid, but it's a difficult one to answer. I aim for the safe side, where my 2hr post meal reading is <1mmol above my pre-meal reading.

In terms of spikes, liquid carbs will result in the quickest and sharpest spikes for me, so honey, fruit juices etc, but quantity is key here when it comes to how long that spike lasts. Next up is high carb solid foods, but low fat, low protein and low fibre options - dirty, nutrition free (but my favourite) white rice being the worst for me, seeing a steadily rising and long elevation in BG readings.

However, just to keep the mystery of diabetes alive, the overall composition of your meal also has an effect. High fat, high protein, and/or high fibre can all slow the digestion of higher level carb items to a rate your body can handle. However, if it's a high enough level of carbs too, these combinations can result in a slower rise to peak levels, sometimes needing 3+ hours to see, and causing that eventual spike to last longer too. Portion control of offending carb items, combined with adjusting quantities of fat/protein/fibre as needed, is the best (but very time consuming to test) route in these scenarios when designing meals.

It all comes down to each of our individual insulin resistance levels, so a CGM is the only option that provides anywhere near the accuracy to determine what potentially spikes you and in what quantities/combinations.
 
I’ve applied for the libre 2 free trial and am awaiting delivery of that. I know that will give me a more accurate reading for carbs and what my blood sugar is doing at night. Especially as I am waking up in the 7-9 range.
Trying to get my results from carbs now as I know the NHS don’t give out testing strips for Type 2 diet only. Plus if I can stop testing all the time, great. Feel like I’m getting unhealthily obsessed with the number on the machine before and after every meal.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn More.…