Somogyi phenomenon and CGM results

It's interesting that they classified hypos as less than 2.2mmol lasting for at least 10min and possible hypos as levels between 2.3 and 3.5mmol.

I tend to run my glucose levels fairly low, and tend to have morning readings from 4-5.5mmol. I also don't use very much insulin at night (I have a pump).
Last year I was waking up sweating but with normal glucose readings when I tested. A cgm confirmed that I was going into the 3s (so not that low in the above classification) but then rising again ie my liver was doing what it should do and releasing some but not too much glucose.

The slightly surreal thing was the CGM alarming and waking me after my BG had risen (there's a time lag on a CGM) and then watching the level rise on the screen. One night this happened twice, the second time I slept through the alarm and had no symptoms. I'm obviously lucky enough to still have a counterregulatory system that still works quite well
My doctor still felt it was better to be cautious and I reduced my bolus at the evening meal so going to bed slightly higher.

Can you remember how much it rose to?

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mid 5s, not high at all.

Hi, my daughter is 5.5 years old and diagnosed just over 2 years ago. We manage her condition with pump and CGMs. She has worn the CGMs pretty much 24/7 for over a year.

Her insulin requirements are quite low (she weighs 17kg and averages 6-6.5 units a day) so we assume she is still producing some of her own insulin.

We have seen this phenomenon on a few occasions when her CGMS does not wake us in time. She drops down into the 2s and then SHOOTS up to hyperglycaemia (sometimes has high as 14+).

I guess, as with many things with diabetes, how ones' body responds can be very indivdual....and, unfortunately, how that body responds can vary significantly from one day to the next!

smaynard said:

I guess, as with many things with diabetes, how ones' body responds can be very indivdual....and, unfortunately, how that body responds can vary significantly from one day to the next!

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I've been reading on this topic for my studies so am very interested in this thread. Many studies have been done to investigate the Somogyi effect (alaska - can prob find references if you are interested?) and the consensus does seem to be that it doesn't exist in the general type 1 population. BUT as smaynard says, individual body responses can vary a lot. Could be that Somogyi originally found people like smaynard's daughter who sometimes do show this rebound effect, but that it is quite rare, and large cohort studies would kind of swamp these individual responses.

smaynard, what insulins is/are your daughter on? Is she on a basal bolus regime or is she pumping small amounts of quick acting during the night? Because one of the things people say when refuting Somogyi is that the rise in bg is due to basal running out rather than liver rebound; but if your daughter's pump is quietly putting insulin in all the way through the night, she can't be running out.

PS
I have always pronounced it Som -ODGE-ee but suddenly decided to google how it should be said, and it's SHO- mog - yee. You learn something new every day.

Hi there,

My daughter uses Novarapid, so, as you say, basal running out does not really offer an explanation. Unless, as can happen, she hits an air bubble (with such small insulin requirements even a small bubble can mean she gets no basal for a significant period of time). However, I really don't think that is a likely explanation for going so low and then inexplicably shooting up....you'd expect to see a more gentle curve.

Hope that's useful. Let me know if any further information would be useful.

Best wishes,
Sarah

One further thing I thought you might find interesting, Snodger, is that we've noticed that our daughter's blood sugar appears to rise by a couple of mmol, very briefly, on waking. We discovered this as we always used to calibrate her CGMs immediately she woke (as the 12 hour alarm for calibration would wake her and we'd immediately respond). However, we were then doing small corrections and finding she'd hypo.

So, we stopped correcting and checked blood sugar again in c. 30 mins and it would consistently have stabilised of its own accord.

Now we make sure we don't test until she's been awake for at least 15 mins and this problem has gone away.

Again, I've no idea if this is common with other diabetics, but it is a definite trend for our daughter and if others have similar patterns it could perhaps account for some higher morning readings.

That is very interesting. Thank you. The more I learn about diabetes the more I think the medical textbooks should just read: "Diabetes. Very complicated. Do not apply general rules. Ask the patient!"