Can I have some medical advice?

[Anonymous]

Sorry.. couldn’t resist.

I’m still feeling like a noob with my pump and need suggestions for my sports basal adjustment. Technically I could probably ask my doctors, but their reply is (as always, correctly) going to be: You’ll need to find out for yourself. Which is all well and good, but I want a starting point somewhere.

So … cycling. I do cycle a bit, and the basal rate seems to be fine in the mornings with or without sports (meaning: I don’t change in on the weekends, when I stay in bed lazily, and don’t get any highs). When I get to work, my sugar is typically near the lower end of my acceptable range (90-110mg/dl for me … but we use different units. 5-6.1mmol/l if my internet conversion thing is right). This is the time affected by my breakfast (decent meal with about 60g of carbs) and the breakfast bolus (reduced by 20% for following sports).

However, in the afternoon I obviously don’t have a second breakfast (hmmm…), so the only option so far is to reduce my basal rate. I aim for “half an hour before, -20%”, grab a drink of juice before I head out (25g of carbs) and drop from a sensible blood glucose level (say 5.5mmol/l) to something entirely indecent when I arrive (say 2.2mmol/l).

Obviously too much insulin. Easy so far. As I don’t adjust my basal rate in the mornings (at all), it would appear the mornings are covered by the breakfast and breakfast bolus reduction. Which is rubbish. Now I don’t know what would happen without brekky and I have lows in the afternoon. Any suggestions on how much further to drop basal rate in the afternoons?

Insulin used: Humalog (one of those high speed insulin-analog thingies)
Sports used: Cycling at ~18-20mph average speed, heart rate >150, peaking >170 for more than 2 minutes. Typically too tired for max puls sprints in the evening.

[Tim]

As always, your diabetes will ;

[Anonymous]

Thanks Tim.

Doubly, in fact, because not only was that a suggestion value that seems interesting (I tried 50% last friday, which was still too much – blood glucose dropped from 11 to 5.5), but you have somewhat given away that you’d know long distance cycling.

So …all my Paris-Brest-Paris questions will now be headed your way. Sorry 🙂

[Tim]

He he! More than happy to discuss cycling & diabetes all day long! 🙂

[Anonymous]

Now I just need a way to sneak Diabetes into every bike-discussion. Possibly by starting my posts with: I tested my blood glucose just now and found I had a 9.3mmol/l. Now I have trouble deciding wether I am allowed a mountain bike along with the road bike and the rando-bike. Help me convince my wife that three bikes are not too much! 🙂

[Tim]

The one (and only) advantage about running your own diabetes web site is that you can discuss what the hell you like – so it’s cycling all the way! @Alison may object but it won’t be first time we’ve bitterly, bitterly argued*

I think you should get a mountain bike. I got one last year after being a committed road bike person for years. As I live on the doorstep of the Pentland Hills there are tonnes of good tracks within ten minute’s ride, so it seemed silly not to. Mountain biking is a different discipline and I find the style different from road-biking but it’s bloody good fun.

As my starter bike I went for a Specialized Hardrock – it’s not particularly rugged and as a result I keep breaking it but it was relatively lightweight (though about three tonnes heavier than my road bike!) and relatively cheap. If I was buying again, I would probably save up a few more hundred pounds and go for something tougher.

* this isn’t true by the way.

[Anonymous]

I bought a cyclocross race-bike last winter, as I finally had to admit that slick tyres don’t work all that well on snow and ice. Which is probably more than a little stupid, as new tyres might have done the trick, but I blame that on something else. Sleep-deprivation due to little child, maybe … or onset of old age. Or something.

However, it looks like there might be enough room in the shed for a roadbike and a mountain bike. The bicycle test said I need a “touring fully”. Which only helped a little bit, if I’m honest – but I accept and appreciate that I’m not looking for a downhill racing bike. Luckily, we have (at least) two rather good bicycle internet shoppy things over here. Their bikes are usually tested as “bloody brilliant” and they are a LOT cheaper than the ones in the shops. With the obvious drawback that there is no local salesperson you can beg to fix it all. Components are usually about two grades higher than what you get for the same cost in the shops, though.

And … it seems my wife actually supports another bike. Which makes me wonder – does she want me out of the house? (<- this also isn’t true :).

[Anonymous]

Part 2: 400km Brevet “Around northern Ba;

[Tim]

Epic posts there @Flo123! I enjoyed them!

[Anonymous]

Not sure if this will be useful for you super-cycling heroic types, but I found a good website that suggests how to adjust extra carbs/insulin reductions for exercise: http://www.excarbs.com/
Interesting basic suggestion is that you should aim to replace 1g of carbs for every kg you weigh per hour. (So a 70kg person exercising for 30 mins should take 35g extra carbs or compensate for that amount by reducing insulin). They get more technical than that but I’m looking at the easy options first! Haven’t tried it out yet of course…

[Tim]

That looks interesting – though the maths looks insanely complicated. I struggle with basic arithmetic at the best of times…

[Anonymous]

Naha! Actually it’s even easier and better. I (or rather http://www.excarbs.com/ ) calculate my cycling on a brevet to use 65-70g of carbs per hour. I can supply this by a combination of reducing basal insulin and eating, eating, eating.

This is total genius.

For my post-work-home-sprint, I apparently need 80g of carbs per hour. Which makes sense, as it’s more intensive, as it’s shorter.

This is total genius again.

I understand it now. I think. Practise to follow on monday (independent of weather) or the weekend (if it’s sunny).

[Anonymous]

Before this all goes completely off-topic (the diabetes topic, that is), I thought I’d share my bicycle cycling experience on the two brevets I did this year. Complete with insulin types used and stupid mistakes made and everything. Might come in handy for someone else looking into it. Possibly. At least I’ll be a bad example.

Part 1: 200km Brevet “Along the Altmühl River [6]”

Insulins: Lanthus basal, Novorapid bolus. ICT with one Lanthus injection in the evening.

The trip started on a fine Saturday morning. I reduced the basal injection the night before (around 9pm) to 75% of normal [1]. The morning after I had to get up at stupid-o’clock to travel to the starting point. A large breakfast with loads of tasty carbohydrates was consumed – with slightly more Novorapid to cover for the lack of basal insulin. Morning blood glucose wasn’t too bad, actually, which surprised me with the reduced basal rate. After that: cycle to the train station, hop onto a train and check the blood glucose levels, approximately 1.5 hours after breakfast – a duigusting 220mg/dl (12.2mmol/l) was the result [2].

Commence heroic correction (yes, that was stupid)! Meet up with all the other strange people, who enjoy cycling until it hurts, for a common breakfast at the starting line. Another blood glucose test found 80mg/dl (4.4mmol/l). Which I considered a bit low, just before sports. The correction for the “low” consisted of three pieces of cake – without a bolus injection, which turned out to lead to a high blood glucose during the morning – which isn’t that surprising, in hindsight).

Start of the actual event was at 9.15h in a large group of cyclist in front of a backdrop of black clouds, sunshine and a strong tailwind. Up to the first control (places to stop and get a stamp at – to prove you went the right way) I then had to keep correcting my way too high blood glucose (I used Novorapid at 1 I.E. per 50mg/dl(2.8mmol/l) reduction – which is identical to what I use outside of sports [3]). I attempted to test my blood glucose on the bike with the Accucheck Mobile taped to my top tube – which didn’t work. At all. The lancet device requires two hands. We did, however, stop occasionally allowing me to test. For the record: The highest blood glucose tested during the beginning of the event was 500mg/dl (27.8mmol/l) [4].

After roughly 75km (46 miles) my blood glucose had dropped to 120mg/dl (6.7mmol/l) and no further corrections were necessary. The speed at which we were travelling was set to about 24km/h (14 miles/h) – brevets are not a race, more of a friendly cycletour – so I felt quite happy at this blood sugar levels.

At that time, I fell back to my normal feeding plan for cycling. Which is not ideal for weight loss, but I’m all for the “can’t have everything” motto. Approximately every 45 minutes I consumed 40g of carbohydrates in ;

[Anonymous]

Thank you for the link, Hilary.

Edit for clarity: Everything below the line I’ll draw is my napkin math and can probably be safely ignored:

From what I’ve seen so far: I managed a combination of eating 60g of carbs per hour and reducing bolus for another 5g of carbs per hour (tentatively – my math is dodgy there). This is very very close to what they calculated for a 90kg athlete (which wasn’t all that wrong, if I’m generous) as the maximum edible. I will personally aim for 65-70g of carbs per hour for long distance events in the future, but I will try to get more of that from basal reduction and less from food. It’s ridiculous to have to eat that much.

——————————————————————————–

(^ that there is the line I drew. Anything from here on is probably useless).

I’ve bookmarked it and will check it back after the next longer ride to see if it holds up. Might as well use the forums for some napkin math, because I usually work better with my numbers than generalisations.

Recent experiences of mine (been testing since we started this post):

Example 1: Start at a blood glucose of 200mg/dl (11.1mmol/l), reduce basal rate half an hour prior to sports to 30% of normal (reduction by 0,6 I.E./hour) for 1.5 hours (so 0.9 I.E. less than normal in total), eat 36g of carbs 1 hour before sports, using 20% less bolus (in this case: 3.6 I.E. normally are reduced to 2.8 I.E.). Give a bolus to reduce the 200mg/dl (11.1mmol/l) down to 100/5.6 – my designated target. Use 20% less than normal for this due to the following sports (1.6 I.E. instead of 2 I.E.).
After 30 minutes of vigorous cycling (which is not in the list, but we’ll guesstimate later), blood glucose drops to 50mg/dl (or 2.8 mmol/l).

Example 2: Start at a blood glucose of 200mg/dl (11.1mmol/l), reduce basal rate half an hour prior to sports to 20% of normal (reduction by 0.7 I.E./hour) for 1.5 hours (so 1.05 I.E. less than normal in total), eat 36g of carbs 1 hour before sports, using 20% less bolus (in this case: 3.6 I.E. normally are reduced to 2.8 I.E.). Give a bolus to reduce the 200mg/dl (11.1mmol/l) down to 100/5.6 – my designated target. Use 20% less than normal for this due to the following sports (1.6 I.E. instead of 2 I.E.).
After 30 minutes of vigorous cycling (which is not in the list, but we’ll guesstimate later), blood glucose drops to 100mg/dl (or 5.6 mmol/l).

Result 1: Ignore Excarbs limit of 50% [here: http://www.excarbs.com/insulin-injections-pumps-and-exercise/ ] (in my case only – I think it’s a good starting point).

Result 2: 20% seems the way to go for a fed and watered, high starting glucose. Adjustments and meal boluses of 80% are good.

Long distance comparison guess:

I have to guess here, as I don’t have the proper numbers any more. I used a basal rate of 70-75%, and I have to pretend that both Lanthus and Levemir are smooth (otherwise I can’t calculate it). That gives me a reduction of:
Case 1: (4-1=1I.E. per 16 hours for daytime dose of Levemir) -> 0.0625 I.E./hour
Case 2: (12-3=9I.E. per 16 hours for nighttime dose of Levemir) -> 0.5625 I.E./hour
Case 3: (16-4=12I.E. per 24 hours for dose of Lanthus) -> 0.5 I.E./hour

Result 1: No wonder the pump makes things easier. Those doses are off by a factor of 10!
Result 2: 1 I.E. of insulin accounts for 10g of carbs, so if reducing my basal rate by 1 I.E. accounts for 10g of carbs less eaten (that sentence makes my head spin – sorry. I’m a foreigner), then I basically accounted for 5g of carbs per hour with my insulin (no wonder it wasn’t enough on it’s own).
Result 3: The only number I have nailed down is 1000g of carbs over 16.5 hours (which is the total time before DNF on the second attempt minus the two hours of no-food at the beginning). This comes out to 60.6 grams of carbs per hour. Which is very close to what they calculated here: http://www.excarbs.com/adjusting-carbohydrate-for-exercise/ .

That was the number I could squeeze into myself without bolusing by eating as much as I could keep down. It included two rest stops at McDonalds (where I’d usually eat more, but that time barely managed two large fries and a half eaten hamburger plus two cokes at the first stop and two breakfasts plus two cokes at the second), two petrol station with a sandwich and coke each and loads and loads of bananas and cycling type gel foods. I think they are pretty much spot on with “you cannot eat more than 60g of carbs an hour”. Next time I’ll reduce basal rate more, though.

[Author]

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