Type 1 Keto

A Tale of Two Pilots. Paragliding with Type 1 Diabetes


I did something a bit daft the other month. I got my old paraglider out and started re-training.

It was the paragliding community that welcomed me with open arms after I lost my Pilots Licence because of Type 1 diabetes. A couple of years after I resurfaced from the shock of a Type 1 diagnosis and getting to grips with the challenges of managing it, I decided to get back into flying.  Having a job and a family, I was in a constant state of being out of practice, and the first flights back after a break were always a bit nerve-wracking. But it was always eventful and fun, accompanied by that adrenaline-fuelled feeling you get when doing something that is considered risky.  I stopped flying seven years ago after my circumstances meant that it wasn’t something I wanted to do. But the time is right again, and I’m young enough. Many pilots are flying well beyond my age and late into their retirement years.

The skill level required to fly a paraglider is not that great. In essence, you have two handles on lines attached to the wing’s back edge. Pull down and lean to the left to go left, right to go right, and pull both down to slow down or land, release to speed up.

It is the skill of reading the weather, reading the flying site and staying up that requires practice. A lot!

When actually flying, there is not much energy required. Taking off requires a bit of gentle heaving and running. Landing is generally soft and requires little more than turning around and walking towards the wing, sometimes briskly! There can be a bit of dizziness with repeated turns to follow the rising air, and there is some white-knuckle ‘clinging on’ when you get scared if the air is a bit too lively. Sometimes it is not easy to distinguish mild air-sickness from a hypo. Modern harnesses are luxurious and, conveniently for people with Type 1 diabetes, there is plenty of opportunity for in-flight food and drink and access to your phone screen to read the continuous glucose meter. Finger-prick glucose testing is technically possible, but with the risk of dropping the kit and the hazards of being distracted, it is practically impossible.  A continuous glucose meter is a must-have, really.

All of the physical effort needed to paraglide is on the ground. The kit weighs between around 10-20kg, and it has to be carried in a rucksack. Pilots prefer an easy life, and you will find most flying sites close to a car park on a hill. But walking a mile or two is not unusual. Sometimes you don’t always land close to your car. Unplanned walks up hills are not uncommon, especially with rookies such as me

So, a few unpredictable elements creep in; an unexpected walk, an unscheduled wait whilst hoping the weather will improve, a short flight unexpectedly turning into a long flight. I have flown non-stop for over two hours, many pilots as long as six hours or more.

One major constant in paragliding is the unpredictability of the weather!

What prompted me to write this was the experience I had recently, using keto management and how it compared starkly to the last flight I did seven years ago on high carb ‘usual care’ management. It is more a blog about approaches to management than exact calculations and applies equally to pens or pumps. 

I have joined a school to get some refresher training.  I am Pilot B, a person with Type 1 diabetes on a keto lifestyle. (HbA1c in the non-diabetes range). My old friend from seven years ago is Pilot A, me with Type 1 diabetes following a usual care high carb lifestyle. (HbA1c around 60-70mmol/mol)

The day panned out as follows. Our group of three was contacted early on and told to meet up at a different location and later than previously planned because the flying site was not yet finalised!  Here is diabetes management issue, number one. And we haven’t even started! Managing the timing of insulin and meals around anticipated activity. The drive to the meeting place was one and a half hours,  then another thirty-minute drive to the flying site.  A 700-metre ascent followed this in two stages. The first stage was a steady ascent over 45 minutes carrying an 18kg backpack. That ended with an hour practising the skill of ground-handling the wings on a slope. This was because the wind ‘on top’ was far too strong and unflyable for our level of skill.  The second ascent was steep and took another half an hour. It was very taxing on the muscles and required a few recovery stops on the way. There was a lunch break whilst everyone recovered on reaching the top of the hill.  On a typical day, flying would start within half an hour of getting to the top, but the wind was far too strong on this occasion. So, after a four-hour wait, a decision was made to launch with a plan to fly to the bottom of the hill. This would have been a five-minute flight. In the event, there was some excellent flying which lasted an hour. A 20 minute downhill walk followed this to the car and a 90-minute drive home. So, as you can see there are lots of situations requiring adept  diabetes management.

So, how did the day pan out for our two pilots? How did they manage their ‘usual care’ sugar-burning and ketogenic fat-burning metabolism  on that day?

Pilot A has been following usual care. This means that 50% of their diet comprises carbohydrates with healthy whole grains and fruit, according to the latest guidelines.

Pilot A would likely have seen the excellent document produced by ‘Runsweet’, which is designed for usual care. They would follow the algorithm as in the diagram below. They would need a certain level of educational attainment to follow it.  They would be aware of the hazards of Insulin on Board (IOB).  Pilot A would have begun planning insulin regimens the night before. Possibly reducing basal insulin to ensure that there was not too much IOB. At this stage, Pilot A would not know how the day would evolve, so they would be cautious with a breakfast bolus insulin, knowing that some physical activity would happen that day. But they would need to inject insulin because, firstly, Pilot A’s breakfast would typically contain significant carbohydrate. After all, it is commonly but erroneously believed that one needs to eat sugar for energy. Secondly, it is frequently advised that people with Type 1 diabetes need carbohydrates if they take insulin. This is equally untrue but is commonly suggested in current practice. See www.zerofive100.com for reasons why.

In the event, significant physical activity was delayed by a few hours and happened closer to lunchtime than breakfast. Pilot A might have needed a snack to cover a hypo because of the effect of the breakfast  bolus of insulin insulin. Or, more likely, they would have had high glucose due to reduced breakfast bolus insulin in anticipation of the exercise that never happened according to plan. Sometimes it is difficult to know which way it will go. It would be unwise to take a correction bolus insulin dose at this particular time in any case.  Pilot A is in a group of fellow student pilots, so would prefer not to disrupt the day by having a diabetes related incident such as a hypo. They came to fly today, but a helicopter medivac due to a disabling hypo is something to be avoided at all costs and does not count as a flight! So, Pilot A has to plan for that hike up the steep part of the hill. Blood glucose is likely to be higher than they would like. Is there enough insulin on board? Or is there too much, and the glucose is going to go down later to hypo levels? That would be less likely but easier to manage by simply consuming glucose tablets. Glucose tablets are reliable and have specific amounts of glucose. They are good medicine in that sense.  Would it be best to anticipate a hypo and snack, or best to wait and chase the glucose level?  What about checking ketones to assess IOB? Do any T1 carry ketone meters daily? If the glucose turns out to be high, might that be the start of ketoacidosis?  More so because of the reduced breakfast bolus insulin in anticipation of the exercise that had yet to begin?

In practice, many people with Type 1 diabetes find that glucose levels flatten out with steady physical activity, and Pilot A was no exception. They were okay with glucose control to that point and had worked out their optimal dosing strategy through trial and error.  They were managing more of a peak and trough trace on a CGM, but it was not causing major issues. On the last hike to the top, Pilot A consumed carbs at the rate of 1g per kg per hour as suggested in the protocol. That is probably 70 grams of carbohydrate. They might have considered covering some of that with insulin. But do they do this when consuming the carbs or, better in this situation, wait until they finish the strenuous activity of a steep climb?

That was a tough climb with plenty of calories consumed from using glucose for energy for sugar- burning Pilot A. Glucose management is now requiring some thought. When are we going to fly? Are we going to fly? How long will the flight last? Or are we going to have to walk back down the hill, taking an hour to do so? How is Pilot A going to manage lunch? Is Pilot A going to have lunch? Very likely. Usual care emphasises three meals a day plus snacks as needed. What if the wind drops and they fly just after lunch when bolus insulin has a maximum effect? And then get possibly an hour or two in the air? Should Pilot A consume some glucose tablets before launch? Or what if glucose is in the mid-teens? Will that affect the clarity of thought? Another test for ketones? Is Pilot A going to need to reduce the insulin dose that covers the lunch? Bearing in mind that the level of physical activity will be at the level of active gardening from now on, if they get a flight, that is, there won’t be a high energy expenditure. So that would be un-necessary.  However, if they have to walk back down the hill because the wind continues to blow strongly, diabetes management will need to be changed, yet again! Possibly more glucose. 

Oh, and we must remind ourselves came out here to enjoy the day! Pilot A did enjoy themselves, and through careful planning, it was without incident. They had a pleasant hour flying with no diabetes-related incidents.  Pilot A would be monitoring well into the evening and adjusting insulin and glucose as suggested in the algorithm.

Pilot B, who was also taking part in the day, had adopted a ketogenic lifestyle some years ago. Pilot B is a fat-burner. They will be using internal fat stores for most of their energy.  Pilot B had managed to halve their insulin volumes since they gave up large quantities of carbs when they transitioned to keto.  Pilot B would still have had to consider Insulin on Board, but it would be less likely to cause a problem. Pilot B also routinely divides basal insulin into two doses 12 hours apart to reduce complicating insulin even more. Pilot B would inject the usual dose of basal insulin. On more strenuous days they might have reduced by a unit or two. Because Pilot B is in a fat-burning metabolic state, they will be producing ketone bodies naturally. Pilot B would be starting the day with ketones around 0.5-3mmol/l. But they did not measure them as they were confident that they were in nutritional ketosis, which is typical for a ketogenic lifestyle. Pilot B would work to the simple algorithm set out here.

Pilot B typically skips breakfast and has a late lunch. It would be slightly different today. They are used to fasting for 16-18 hours a day.  They decided that day to extend the fast to 24 hours, use glucose for hypos if needed, and eat at the end of the day. Just drink water all day and forget about food and the diabetes issues that go with that. Pilot B woke with glucose slightly higher than usual and used two units of bolus correction dose of insulin without food. That would hopefully tame the glucose caused by dawn effect and that dose of  insulin would largely have lost it’s potency by the time they arrived at the meeting place. They always carry glucose tablets and  are aware that any insulin injected, even in small doses, might  lower glucose sufficiently to cause a hypo. But the smaller the dose of insulin, the less room for error, and the less severe the hypos. In fact, Pilot B has far fewer hypos on a keto lifestyle. Which adds a huge margin of safety when doing something like this.  Pilot B would not feel hunger because a keto diet suppresses appetite. They would be happily burning their internal fat stores, which are there for that reason. 

Pilot B’s CGM failed during the ground handling part of the day when the harness dislodged the sensor. So Pilot B was left with no option but to use fingerpick testing. They had, of course, remembered the glucometer as this was a sport requiring frequent safety checks, especially around diabetes.

The glucose was on a plateau at that point, a shade over 10mmol/l. There was nothing to do. Plateaus are safe places. Pilot B would trade the higher than optimal glucose for safety on this occasion. The next time Pilot B considered their diabetes management was at the time of preparation for flight, four hours after the CGM failed. It was still on a plateau, now just below 10mmol/l but higher than physiological(4-7mmol/l). But this was okay. Pilot B had no excess Insulin on Board that was going to cause a problem. No wild swings of blood glucose were going to happen. Pilot B had left those behind when they adopted a keto lifestyle.   Pilot B would have used a couple of units of rapid in a typical daily setting but decided not to use this correction given that this was not a typical day.  Sometimes basal insulin can exert a late effect and lower the glucose, but on this day, it was not the case. It was likely glycogen release and adrenaline were preventing this and having the effect of raising the glucose slightly above ideal.

Pilot B had a lovely hour flying and a day that required diabetes planning, but it was far less intrusive than Pilot A’s management regimen. Pilot B had a meal in the evening with a normal basal and bolus dose. No allowance was needed for physical activity in a fat burning metabolism. They checked their blood glucose before bed when it was normal. After that, there was no further checking until waking the following day when physiological glucose levels had been restored, and the CGM sensor was replaced.

This is the real world of Type 1 diabetes: same condition, same activity, two different experiences. Pilot A managed their day as a sugar burner(usual care), and Pilot B worked their day as a fat burner (keto lifestyle).

 But that was just an example of a single day. Both Pilot A and Pilot B would make the same sort of calculations the next day and every day for the rest of their lives.

Yes, with Type 1 diabetes, you can do anything you want, as they will tell you. But some options make life easy, and it is a shame that many people with Type 1 are forced into being  Pilot A because there is a lack of information available to them. And fewer than ten per cent of people with Type 1 on usual care like Pilot A are meeting guideline targets, according to the National Diabetes Audit of England and Wales. People might choose differently if they knew there was an option where ninety per cent could reach the target, like Pilot B*. Pilot ‘A’s are the ones who are winging it; excuse the pun. We should do all we can to keep them safe, which means making sure they have all the information available on alternative options to manage their diabetes. Of course, Pilot A and Pilot B might choose to make the same diabetes management choice that they are already using. But it will be their choice based on their own assessment of the complete information and their lifestyle needs at the time. And that is the way it should be. 

* https://pubmed.ncbi.nlm.nih.gov/29735

Leave a Reply

Your email address will not be published. Required fields are marked *