Going the distance

Last year Ben Trollip set himself the challenge of completing a marathon to raise funds for Diabetes NZ. Here he shares his story and some practical tips on how to train for a marathon.


While I’ve always run to keep fit, I had only completed one half-marathon before I as diagnosed with type 1 diabetes shortly before my 29th birthday. As many of you can probably relate, I spent the first few months wrapped in cotton wool; scared to do anything that might upset the delicate balance between insulin and blood glucose. However, I can still remember the feeling of elation when I was given the all clear to have my first light jog. Since then, running has become a meaningful part of my lifestyle.

Running marathons is a personal challenge I would never have thought I could achieve when I was first diagnosed six years ago. But last October I ran the Auckland marathon to raise money for Diabetes NZ and this year I’m doing the Hawke’s Bay Marathon, in May, and the Chicago Marathon in October.

So how do you go about training for a long-distance run? Aside from the typical things that everyone should do (stretch, wear good shoes, develop a training programme, maintain a healthy diet, hydrate), there are several things that a T1D needs to think about. I’ve tried to cover the main things I’ve learned below but everyone is different. If I could give one overriding piece of advice, it would be to learn what works for you. Read from varied sources, speak to other people with diabetes, listen to your body and learn from your experiences in training.

One great resource is Runsweet (www.runsweet.com), which is a fantastic website for people with diabetes covering all kinds of sport. It is well worth checking out.


I am on an insulin pump (Medtronic MiniMed) and a continuous glucose monitoring system (Freestyle Libre). Both are not required to run long distance but I find them hugely helpful.

A pump system means that you’re only on short-acting insulin (dispensed regularly by the pump) rather than a long-acting basal shot once every 12 or 24 hours. Doing the latter requires you to plan ahead and adjust your dosage lower when you have a big run coming up. With the pump, you can simply turn the basal rate off and pretty quickly the short-acting insulin works its way out of your system and your blood glucose level (BGL) will begin to rise. I find this very convenient because extended cardio activity makes my BGL plummet and so getting rid of background insulin from my system as soon as possible is a good idea. Before a big run, I will turn off my pump 15-30 minutes before the start. If doing a shorter run (and my BGL is relatively high) I might only turn the pump down to 30-60% of my usual basal rate.

The benefits of a continuous glucose monitoring (CGM) system are obvious. It’s much easier to monitor how your BGL is tracking without having to stop and prick your finger. If you’re not on a CGM, I’d suggest checking your BGL 60, 30 and 15 minutes out from the start to make sure it’s tracking well. I’m now confident in running a half-marathon length without checking my BGL (unless I’m feeling off) but when starting out you may want to plan to check around the one hour mark.


For a long run, I like having as close to zero “on-board” insulin as possible. This is because I find that my BGL will fall quickly after more than 30-60 minutes of constant activity, even if it is only moderate. Because I find a meal bolus can still be having an effect on my BGL three to five hours after the meal, I tend to run in the mornings before breakfast. This means my last meal will have been at least some eight hours earlier. If you prefer afternoon running, I’d recommend not going within four to five hours of your last meal (although, again, see what works best for you).

I don’t eat anything out of the ordinary the night before a race: I just aim for a well-balanced meal. Typically, it might be 40-60g of carbs. Personally, I’ve found that eating something that’s too carb-heavy or fatty can weigh on my performance the next day. I’ll sometimes set an alarm for around midnight to briefly wake up and do any corrections so that my BGL is perfect in the morning. (I don’t want to have to bolus close to the race, as explained above).

Ideally, at the start of the race my BGL is 10-15mmol/L and gently rising. I’ll have a muesli bar (15-20g carbs) as close to the start of the race as I can manage. This serves me well for half-marathons (1:30 to 1:45 hours). However, I do check my BGL if I’m feeling unusually sluggish, and it’s not uncommon for me to take 15g of fast-acting sugar somewhere around the 15km-20km mark. I run with glucose tablets or gels which are easy to consume without stopping.

When training for a full marathon, I found that 15g of carbs (glucose tablets or gels) at around the 20-25km mark and thereafter every 5km worked well for me.


Hypos (low blood sugar levels) are a significant concern. Running with friends or, even better, other T1Ds, is a good way to build confidence. Have a look for a local diabetes running group.

Wear some form of ID that shows that you’re T1D. For races, make sure the organisers know you have diabetes. There’s usually a spot onthe registration form to disclose any medical conditions and I also write it on my bib. Make sure you’ve given accurate emergency contact details.

After a race, keep an eye on your BGL because it’s not unusual to be more susceptible to hypos for the next day or so.

Long-distance running is a surprisingly mental sport. Achieving a good result relies on maintaining discipline and sticking to your plan. My advice would be to accept that sometimes things go awry when you have diabetes. Try to learn from the experience but don’t let it demotivate you. Sometimes perfect planning and management don’t result in a great run for some unknown factor beyond your control. Don’t dwell on it, and look forward to improving at the next opportunity.

Ben shared his story in the Autumn 2019 issue of Diabetes magazine. Subscribe to Diabetes NZ today to receive your copy.

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Jo Chapman