We just had the Olympic Games in Rio and very soon the Paralympics are to follow! We see athletes who have trained for 4 years solid get the opportunity on the world scene to give everything they’ve got – and it is by far the most motivating sporting event the world has. It puts to shame any corrupt and disappointing FIFA football competition, no question!

With that serge of motivation around the world, hopefully, children and the next generation are now going out and embracing the Olympic spirit by trying some of those sports out for themselves, with dreams of one day representing their countries and competing for the medals. The question is from a type 1 diabetes perspective, what might happen to blood glucose levels in the different types of sports we witnessed on display?!

A DiAthlete has to know about what might take place with their blood glucose control during certain activities, in order to prepare and get the best results.

The basic start is really getting out there, an element of ‘trial and error’ and seeing the results for yourself. Living and learning is something we have to do every day with diabetes, the latter part the most essential if ever something does not go to plan.


So let’s review a few different forms of Olympic running events and consider what might be the most likely outcome – albeit always remember every person has a different body and different insulin regime, so there will always be different results – this is just a basic guideline in the rather unpredictable life with diabetes!

To start, let’s begin with Team GB’s Mo Farah who competed and won Gold in both the men’s 10,000m and 5,000m races. What if Mo had type 1 diabetes?

As someone who has raced these distances before, not remotely to Olympic standard (and my comfort zone is in endurance road running: marathons and ultra distance), I know there are two contrasting blood glucose possibilities in this distance of running. If it were fitness training and covering the distance of 5km or 10kms, the most likely outcome would be decreasing blood glucose levels during the run itself, when running in an endurance style – continuously moving at the same rate of pace – however as a race, especially on the Olympic stage, it is far more likely to be the opposite effect, with blood sugar levels actually spiking upwards during the run. This is a result of a changing pace, higher speed and a rush of adrenaline.

This is more common with the 5000m. In this particular race at Rio we saw the Ethiopian runners set the pace early on in the final at quite a fast tempo, leading from the front. Their tactic was to try and burn out Britain’s Mo Farah to reduce his sprint at the finish. This meant the first lap was a standard 5km professional pace, followed by an above-average faster pace which continued throughout the 400m track laps.

In diabetes terms, this change of pace and shire tension in the race would have most likely caused a ‘T1D-Mo’s liver to have reacted by releasing stored glucose into the bloodstream, therefore spiking up the blood glucose levels during the race.

The longer the race went on the more the pace increased, with the final lap being the fastest for the sprint finishes. And we are talking about a crazy, elite sub-13-minute 5km!

Once the race ends that is not it for someone with type 1 diabetes! All of that energy has been burned and that means that the glucose in the bloodstream, even the additional amounts released by the liver during activity, would have been burned up too, just in a slower process. This means in the hours to follow the race, despite that increase in blood sugars which could have meant afterwards T1 Mo’s levels might have been quite high, his blood glucose levels would come dropping downwards. A risk even of an evening hypo occurring.

In the 10,000m race the final in Rio was taken on in a much slower style – albeit with a ridiculously fast time overall set by Farah in just 27 minutes – and this would mean in type-1-talk that blood glucose levels might not spike as high as they would in the more rapid paced 5km. Mo stayed at the back for the first quarter of the 10km final, so our Type 1 Mo would have been keeping quite a consistent tempo going around in the early laps, saving his energy. This would mean in terms of blood glucose, levels would have been possibly decreasing during the run at the start – although do consider that in the atmosphere with thousands of onlooking fans in the stadium and the eyes of the world watching on TV, there’d be a lot for adrenaline pumping through the veins which could also increase levels too – however the pace, similar to the 5km, did increase the further the race went. We saw Mo gain momentum and push up to the front of the pack where he then grew faster and faster to lead the pack. So, again, a T1 Mo would have likely rised up in his blood glucose levels during activity with the liver reacting and releasing glucose into the bloodstream.

Post 10km it would be unlikely for the levels to have spiked as high as in the 5km may have done, as the 5km was more fierce and faster paced. However the post activity drop would be more survire hours later – 10km is longer distance and more energy consuming than a 5km, so an early hypo could happen and also the possibility of a repeat night time hypo is possible in the post-exercise ‘Crash’ of blood glucose.

My way of preventing these drops, especially when as a teen in being very active at a half-decent level of football, was to have a solid high carb dinner with less units of Bolus (quick acting) insulin than the carb calculations required. Maybe even a unit less basal (background insulin) in the evening, on the split routine of morning/night-time injections which I personally am on.

In the men’s 100 and 200m sprints we saw Jamaica’s Usain Bolt, the world’s fastest man, take Gold in both finals. Now there is a big difference between endurance running and sprinting! I have already mentioned the ‘adrenaline-effect’ blood glucose spikes that can happen; for 100m sprinting, a T1-Bolt would definitely have this take place, his liver releasing glucose into the bloodstream. You go from being still and raring to go, pumped with adrenaline, to sprinting for 10 seconds flat-out.

So this means an increase in levels is imminent; however, not dramatic. It is more likely you will see higher levels post exercise in the 5km/10km races or after a game of football (for example), than post exercise in sprinting. This is because the sprint only lasts a matter of seconds – so you haven’t burned as much energy overall.

It also means it is unlikely your levels will suffer the post exercise crash, as you would in those other more enduring sports.


My type of running is slightly mad, ultra endurance. This is on-going, not competing against opponents as such, but against yourself – how much can you take?! Therefore you don’t dash off, you don’t look to change your pace so much, you try and reserve energy until the end. This means you keep things steady, slowly but surely getting the job done. This form of exercise will decrease the levels during activity and means you need to be aware of what your levels are doing during the run to prevent hypos from happening. Tweaking and lowering basal insulin is an essential tactic and a intake of carbohydrates through gels or drinks also a key method to keep levels stable.

At Rio is was Kenya’s Jemima Sumgong who took Gold in the women’s marathon race. So a T1-Sumgong would have had to have been aware of her blood sugars throughout, lowered her basal insulin maybe even to around 75-80% and topped up with glucose in her drink stations.

Everyone is different so different levels can happen, depending mainly around types of insulin and diet. The key with exercise and type 1 diabetes is not to focus on the sport itself to determine what might happen in your blood glucose control, but to consider your personal physical movements, your running style and performance during the activities.


Understanding and testing blood sugars is the crucial part to truly know what is going on and to even learn more. Remember: it is not what the level actually is that counts, it is what the level itself is actually doing, from spiking upwards to crashing downwards; that’s what you need to be aware of in order to make the best decisions. Live, learn and never let diabetes stop you!