Thursday, February 15, 2018

Differing insulin requirements at different times of day

Not the catchiest title for a blog post I grant you but hopefully something worth reading if you are a runner with type 1 diabetes..

I often run twice a day and this would normally be anything from 4-5 miles in the morning and maybe 3-4 in the evening. Not fast or too excitable, just ticking over around 7:45 pace. While the distances and double days are not a problem the insulin requirements could not be more different.

In the morning I run fasted as much as possible, if my blood sugar is around 5-6mmol then I will normally have a small bite to eat with no bolus being delivered. I also reduce my basal by 80%. This very morning my blood sugar was 6.7mmol on waking and because of the weather conditions being pretty awful I knew I’d be working harder. I reduced my basal by 80% and ate around 20g of carbs giving myself 0.5 units of bolus which was around a quarter of what I would normally use if I wasn’t running. When I finished my run, 4.4 miles in around 32 minutes my blood sugar was 7.8mmol. A normal breakfast followed (40g of carbs) with normal bolus (4.5 units to include a small correction) and with the -80% basal still running (I have this set for 3hours) my blood sugar is stable until lunchtime.

Contrast with the afternoon….

I eat my lunch at midday most days and it’s normally the same or similar food. A pitta with some vegetables in it and some fruit. Around 40gs of carbohydrates. My ratio sees 2.5 units on bolus delivered. My basal chugs along and normally there’s balance. But something happens towards the end of the day and my blood sugar starts to drop. This is only around 4-6pm that it occurs (I think this is the case). I know it happens as when I ready myself to run home I need to eat to get my blood sugar up otherwise it does not last. Even a relatively short run home of say 25 minutes has seen my blood sugar go from 14mmol to 2.9mmol in that period. This is combined with an 80% reduction in basal for the same period.

This is not sustainable so recently, and I mean just this week, what I have started doing is suspending all insulin about 30 minutes before I head out the door that sees a reduction in insulin in my system covers the period I am on the move. I did this yesterday and my blood sugar went from 11mmol to 6.7mmol over a 30 minute period. When I get home I resume insulin delivery but at -80% of the normal basal rate.

What is interesting is that this does not happen if I am running an ultra. When I ran in November (my last 50 miler) I had insulin with breakfast and then ran on a -80% basal which until the time the pump failed was working. My blood sugar did drop a little but I would expect that for the effort I was putting in and the demands being made on me. Where I have had a normal day with normal insulin it seems to me that I get a build up or a cumulative effect. Almost like the insulin profiles don’t really apply. Today I also reduced my afternoon basal by 20% while at work to start the reduction process. This has had a positive impact meaning I have had to eat less so there’s maybe a tweak to my basal to be factored in there to.

I am sure I am not the only diabetic to experience this so hopefully this helps, or if someone has a better way of managing get in touch with me!

What this has got me thinking is that the Omnipod is a wonderful piece of kit, after reticence using a pump I am totally sold on it now. It would be even better if you could program fluctuating basal rates without having to create the profile to do it. The profiles work where things are consistent but I don’t always run at the same time, or leave work at the same time. If I could at 3pm think I will probably be leaving at 5:30 and then set a programme to reduce basal by 20% for an hour (1500-1600hrs), then 60% for the next hour (1600-1700hrs) then from 1700hrs to suspend for an hour and a half before resuming at -80% for 2.5hours. That would be awesome!