# Carbs and insulin for half marathon



## Jennyninja (Aug 1, 2021)

Morning ! I'd appreciate your opinions on various ways to get through a half happily and safely.  Yesterday after a fairly long break from running that distance I decided to give it a bash and in general,  especially afterwards,  I felt great about doing it for the first time since starting insulin for T1at the end of April this year.  I've been running for 10+ years and have done this distance quite a lot of times and a marathon in 2019, so I'm used to the challenge.  Only this time of course there is the added challenge of getting the carbs and insulin right. So yesterday I had a normal cereal breakfast at 7.30am, injected 3 units to the 40gs contained.  Since the hot weather I've lowered the insulin from 10% and it seems to be working well so far.( Btw I am on Lantus and Novorapid,  finger pricking right now.  May try Libre at some stage in the future but not yet.). At about 1030am BG was 8, then 30 mins later 7.2 so a downward trend.  I had 1 piece of granary bread and lashings of peanut butter for slow release before setting out. No insulin.  I usually take x1  3gcarb dextrose tablet after 3 miles then after mile if I'm doing a shorter distance but didn't feel the need til mile 6 on this run because of the slow carbs guess.  Then I took 1 tablet roughly every mile thereafter.  Also lots of water.  I didn't push myself with speed but did find it quite challenging as the course was quite undulating and I was not used to it. 40 mins after the run my BG was 11.2. I had some no carb protein but no more insulin. BG by evening meal was 8.2. 4 units to 50g carbs. BG at bedtime 10 which was 2-3mmol higher than usual. BG this am 5.3 which is normal /good for me. Question - is there anything I could have done differently ? I have a half marathon race on 5th Sept and would like to feel as confident as I can that I've done everything correctly.  I know there's always the caveat that different things work for different people but would appreciate any opinion/advice.  Thanks


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## Jennyninja (Aug 1, 2021)

Oh and any thoughts on next day management.  Plummeting BG 3 hours after a less insulin to carbs breakfast this morning was interesting...


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## helli (Aug 1, 2021)

Jennyninja said:


> Oh and any thoughts on next day management.  Plummeting BG 3 hours after a less insulin to carbs breakfast this morning was interesting...


Have you reduced your basal insulin?
I reduce mine by about 20% for up ton48 hours after moderate to heavy exercise.
This depends on the type of insulin you use for basal. Tresiba can take 3 or 4 days for a change to take effect so is not ideal if your needs vary due to exercise (and periods).

I have no experience of long distance running. My usual exercise is an hour on the bike. So I cannot provide advice to maintain levels over longer times.
However, you may find runsweet.co.uk useful. This is a site dedicated to exercise for people with Type 1 diabetes.


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## Jennyninja (Aug 1, 2021)

helli said:


> Have you reduced your basal insulin?
> I reduce mine by about 20% for up ton48 hours after moderate to heavy exercise.
> This depends on the type of insulin you use for basal. Tresiba can take 3 or 4 days for a change to take effect so is not ideal if your needs vary due to exercise (and periods).
> 
> ...


Thanks @helli . I'm on Lantus basal.  Effects are fairly quick as I've recently reduced due to hot weather and noticed the difference.  I'll check out runsweet.co.uk too


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