High blood sugars after half marathon

[pinewood]

I ran a half marathon on Sunday morning. During the race itself my sugars were constantly dropping so I was consuming around 8-12g of carbs every 15 mins or so and cruised along in the 4mmol range. After the race I remained stable but then for the rest of the day and yesterday my sugars were all over the place; mainly insanely high and not responding to my bolus injections as they usually would.

For example, I had a burger and fries on the evening of the race (the race was early in the morning) and this meal would usually be in the region of 6 to 8 units of NovoRapid for me (at a push); however I needed 12 units and still stayed high (i.e. 12mmol) over night. Finally came down to normal levels at 5am-ish after multiple Dexcom high-sugar alarms and subsequent correction doses through the night.

I'm hoping I'm back to "normal" today (so far so good) but any ideas what happened?

I was wondering if the "stress"/cortisol release of the run could be to blame but then my muscles were aching so badly all day I'd have thought they'd be sucking up the glucose. Last time I ran a half I was fighting off lows!

 

[Bebo321]

How much training did you do in advance? If you had aching muscles the day/two days afterwards you weren't perhaps as prepared for it as you might have been. Consequently your body would have been put under stress and yes you would most likely have elevated cortisol levels for a couple of days afterwards. I know of a chap who after a marathon had high bloods for over a week afterwards.
Falling bloods during the run was most likely down to having too much circulating insulin, but it's hard to know without knowing what your 'prep' was.
Remember that once your bloods are over around 12mmol/l then the amount of insulin required to reduce your bloods increases on an exponential curve (I can't recall where to find it, but there is a research paper that plots the trajectory). Basically it means that once you hit particularly high blood glucose levels, you need twice as much insulin (or more) to lower it by the same degree as you would within a more 'normal' range.
Well done for doing the run though - how did you do?

 

[Juicyj]

Hi @pinewood Well done, that's a great achievement

I am inclined to also ask the question about insulin on board - did you have any either basal or bolus ? I wouldn't think stress hormones unless you hadn't done the training for it and so were under pressure during the race. I would of thought it was your muscles repairing and replenishing that would of caused the fluctuations afterwards.

 

[pinewood]

Thanks both!

I didn't do that much training in advance (and certainly not as much as I should have done) - I run c. 5km fairly regularly (3 or 4 times a week, usually) and did a couple of long runs as prep for the half but should have done some more distance training to improve my endurance. I did manage a time of 1hr45 (a PB for me) but ached afterwards and pushed myself fairly hard.

I had a small bowl of cereal and a banana with 2 units of NovoRapid at 5.30am and the race started at 7am. The cereal and banana would usually be 3.5 to 4 units for me, so I reduced down to 2 because of the marathon. I guess I should have reduced further given that my levels kept dropping during the race. The night before the race I reduced my Lantus from the usual 14 units to 9 units; perhaps that also played a part in the post-race highs and I should have left it at 14 and done without the NovoRapid instead?

@Bebo321 I definitely do become significantly insulin resistant when my levels go above around 10mmol. I've now learnt that when I'm in double figures there is basically no point in injecting anything less than 3 units as it simply doesn't do anything.

 

[Bebo321]

Thanks both!

I didn't do that much training in advance (and certainly not as much as I should have done) - I run c. 5km fairly regularly (3 or 4 times a week, usually) and did a couple of long runs as prep for the half but should have done some more distance training to improve my endurance. I did manage a time of 1hr45 (a PB for me) but ached afterwards and pushed myself fairly hard.

I had a small bowl of cereal and a banana with 2 units of NovoRapid at 5.30am and the race started at 7am. The cereal and banana would usually be 3.5 to 4 units for me, so I reduced down to 2 because of the marathon. I guess I should have reduced further given that my levels kept dropping during the race. The night before the race I reduced my Lantus from the usual 14 units to 9 units; perhaps that also played a part in the post-race highs and I should have left it at 14 and done without the NovoRapid instead?

@Bebo321 I definitely do become significantly insulin resistant when my levels go above around 10mmol. I've now learnt that when I'm in double figures there is basically no point in injecting anything less than 3 units as it simply doesn't do anything.

I think you're probably right in the suggestion to have left the basal. The trouble with having the banana at 5.30am meant that the insulin would have been pretty much peaking in action at the beginning of the race. Your adrenaline might have kept you up initially, but the fact that your bloods then took a tumble (not excessively, but enough) probably shouldn't come as a surprise.
@Juicyj is right about muscle repair - there are a number of hormones that come into play during recovery. A likely elevated level of cortisol is just one of them.

 

[Bebo321]

Excellent time run by the way!!

 

[TheBigNewt]

6U for a burger and fries ain't enough (as you ultimately found out). Takes me about 12 too. Fries are killer for blood sugar dude!

 

[pinewood]

6U for a burger and fries ain't enough (as you ultimately found out). Takes me about 12 too. Fries are killer for blood sugar dude!

Firstly, it depends on the portion size and post-meal activity level and secondly, everyone has their own ratios. As I mentioned in my initial post, I have tried and tested this meal many times in the past and 6-8 units has always served me well (usually as a 3 unit pre-bolus and 3-5 unit post-bolus).