The Spartan Beast in Killington, Vermont is a tough race. Imagine trudging 15 miles up and down a mountain, with 30 obstacles to complete – walls to leap over, sandbags to carry, ropes to climb – and penalty burpees to punish any failures. It takes the average racer about 8 hours of full-tilt effort to finish. Tough for anyone. Now imagine it all with Type 1 diabetes.
But I knew that proper preparation and my low-carbohydrate diet would help see me through the event without the risk of rollercoastering blood sugars to ruin my day.
I searched the web far and wide for advice on how to tackle this event with T1D, and while I benefited greatly from the words of many more experienced athletes, I didn’t find a single webpage that addressed the topic in the type of detail I wanted to see, nor any single page that addressed how to do it with diabetes and on a low-carb diet. And so I wrote this guide, explaining my own decision-making process and my results:
About Me
It was less than two years ago that I was diagnosed with Type 1 diabetes, and in my first month using insulin I was so wary of hypoglycemia that I was careful not to even walk outdoors alone more than absolutely necessary. Exercise was an unknown to be feared. But soon I discovered that people with T1D are capable of amazing athletic feats – they can run ultramarathons, play elite professional sports, and hike the Appalachian Trail– and that given some careful planning, diabetes was no real barrier to sporting ambition.
Not that I was capable of anything like that. I am not a superb athlete, I’m just a regular guy. So why did I sign up for such a brutal event? Simply put, my diabetes has helped motivate me to push beyond what I thought were my limits. And so when some younger, fitter friends encouraged me to sign up for the Spartan Beast, a day of physical effort the likes of which I’d never before experienced, I said ‘yes.’
It took a lot of planning to be able to approach this race safely. Most participants spend much thought carefully tweaking their outfits, their equipment, and their nutrition, but when you have diabetes, all of these variables are suddenly hugely magnified. What diabetic equipment would I bring? How much sugar did I need to pack? How much insulin to take? How should I change my glucose targets?
The Event
The Spartan Beast on Killington Peak is well-known among competitors as one of the most merciless courses on the whole Spartan circuit, primarily because almost the entirety of the race is on an incline. The legendary feature of the event is the so-called “Death March,” a mile or longer walk straight up a steep ski slope. The entire race totaled something like 15 miles, with nearly 7,000 feet of elevation gain, which makes it a more serious climb than most seasoned hikers would attempt in a single day, and that’s not even counting the 30 unforgiving obstacles.
My assumption was that my blood sugar would drop during the day, as it often does during cardiovascular exercise, but I was prepared for anything.
Equipment
In anticipation of a trail that would include mud obstacles and swimming, and with rain in the forecast, I decided I didn’t want to feel burdened by my iPhone, through which I receive readings from my Dexcom G6. I figured that there was no small chance that I would faceplant in the mud and short-circuit my equipment. So I decided to forego the use of my CGM. The sensor remained attached to my tricep, but I wouldn’t use it for glycemic management. (I used no special precautions to protect my Dexcom sensor and transmitter from mud or water. They were both fine, and continued to work perfectly after the race.)
That left me with my trusty old glucose monitor. I packed the monitor, my lancet, alcohol pads and a couple dozen testing strips into a small watertight bag. The alcohol pads were important, because it is otherwise impossible to wash one’s hands in the middle of the race. The bag itself slipped into the back pocket my hydration pack. Most racers carried a hydration pack, to provide water between the 10 or so official watering stations on the course, and to carry a small amount of snacks and equipment.
Every once in a while during the race I would sit down, patiently remove my testing equipment, clean off one filthy finger with an alcohol pad, and take a blood sugar reading. This slowed me down by a few minutes every time, but it was very important to keep an eye on my levels, as it’s undoubtedly more difficult to perceive the early symptoms of hypoglycemia while battling exhaustion, covered in mud, and bounding up and down a mountain. Frankly, it was a nice excuse to take occasional breaks.
In retrospect, it would have been very easy to run the race with my iPhone – many of my fellow racers had phones, and some even brought portable speakers with them along the way. Although my body was at times fully immersed in water and mud, at the non-elite level there is no rule against setting aside one’s pack to complete an obstacle. The vast majority of the race is on dry land, over which it would have been easy and convenient to have my iPhone in my pocket or in an arm band. In heavy rain, I could have placed it in a Ziploc bag or in the waterproof bag in my hydration pack, which would have at least kept it close enough for any low alerts to be audible.
Having the Dexcom readings easily accessible would have allowed me to target a tighter range for glucose control during the race. Next time, I’ll bring my phone and use my CGM throughout the race.
Oh, and I had one other piece of equipment: a “Type 1 Diabetes” wristband. This was a precaution that my wife sensibly insisted on. Thankfully, I didn’t need it.
Basal Insulin
I decided to reduce my basal insulin injection by 33%. This was a complete guess, because I’ve never put my body through something like this before, neither before diabetes nor after it. However, it’s plain to see that exercise can improve insulin sensitivity, and although it would have been easy to compensate for that during the race by eating more sugar, I was worried about what might happen overnight after the race.
It turned out that my blood sugar was quite steady overnight after the event, so it seems as if the 33% reduction was a good guess. What surprised me was that I had to fight off low blood sugars in the 24-36 hours after the race – a day of exercise this big has an effect that lingers far longer than your average workout. In retrospect, I shouldn’t have immediately resumed my full basal dose, and should have only gradually worked back up to my regular dose over the course of a few days.
I don’t use an insulin pump. My impression is that most pumping adult obstacle racers choose to leave their pumps disconnected for race day, and revert to injected long-acting insulin, if they have it available. This makes sense to me, as many pump models seem fairly intrusive and fragile. Certainly, any model with a tube would seem to be particularly hazardous in a race that involves crawling under barbed wire on one’s elbows and knees, and throwing one’s torso over walls and barriers. I don’t think it would be impossible to participate with an insulin pump, but I would certainly prefer to go without it if it were an option.
Bolus Insulin
I did not bolus for my breakfast. I had a high-protein breakfast, as is my custom, and while I would usually use 2-3 units of Regular insulin to counteract the long slow glucose rise from such a meal, I abstained this day. Even though Regular insulin is mild in comparison to modern fast-acting insulins, it would still peak an hour or two into the race, likely while I was hoofing it up some impossible mountain incline, with my blood sugar naturally cascading down. I felt that it would be safer to forego meal-time insulin entirely. I wanted to eliminate it as a variable.
I did bring a Humalog pen with me in my small waterproof bag. I really, really didn’t want to exercise with fast-acting insulin in my system, and had no intention of using it. But it seemed important to have with me as a failsafe. High-intensity exercise, adrenaline and stress can all spike one’s blood sugar. If I unexpectedly found myself above 200 mg/dL and rising, this would give me the option of delivering a correction bolus and (carefully) continuing the race. Without Humalog in my stash, a rising blood sugar like that could potentially convince me to abandon, something I didn’t want to do.
Fuel
It takes the average participant about 8 hours to finish the Beast. I didn’t know if I was average or not, and expected that it could take me as much as 10 hours. After doing some research on the caloric needs of endurance athletes, I decided that I should pack about 1,250 calories with me. This was my fuel, and it would all be low-carb.
There’s a whole new world of keto snacks to choose from, including a fast-growing variety of specially made goos and bars for Keto hikers and endurance athletes. I settled on a handful of nut butter pouches, each one containing nearly 200 calories of healthy fats and high protein. These pouches are compact and dense with energy, and are easy to eat on the run. Nut butters do contain small amounts of carbohydrates, at least a few grams per pouch. I figured these carbs would do me more good than harm, as I expected to need a steady stream of carbohydrates throughout the race to keep my blood sugar up.
I also packed myself a Ziploc bag of fine Spanish chorizo and good hard cheese. This was a maverick decision, and you don’t see a lot of regular food on the trail. But I’m already on record regarding my love for these naturally low-carb treats, which have been a mainstay on my hikes since long before I developed diabetes. One can only eat so many energy bars and goos. I enjoyed my immensely satisfying gourmet snack at about 4,000 feet, in the fog and wind, at the top of the “Death March.” It’s a popular place to break for food, and I couldn’t help but feel a bit smug when I saw other racers with their measly energy bars.
Was 1,250 calories enough? Even though I finished the race faster than I had predicted, I wish I had brought more food. I was hungry at the end of the race, and after eating all of my low-carb foods, I had to fight the temptation to dip into my high-sugar snacks just for sustenance, which would have sent my blood sugar skyrocketing.
Carbs
Like many with Type 1 diabetes, I find that cardio can drop my blood sugar. It’s not dramatic, and after more than a year on a low-carbohydrate diet, I can usually run or hike quite a bit without needing much glucose. But eventually big days catch up to me and I need to chomp on some candy to keep my blood sugar from going low. This would be by far the biggest exercise I’d ever done, so I had no idea how much sugar I might need to consume. As there’s no food available during the race, this was a good place to err on the side of caution. I brought a lot.
I brought several packs of glucose gel, a small Ziploc bag of Dex4 tabs, and a pack of Clif Bloks, which are sweet gummies with some added electrolytes. All combined, I had more than 150g of simple carbs at the ready, enough to raise my blood sugar some 700 points, which I judged would be far more than I could ever need. But I wasn’t taking chances, as I had no intention of interrupting my event to beg other racers for their food. As I hoped, I only needed a fraction of all this.
Electrolytes
If there’s any group of people that is more obsessed with electrolytes than low-carb dieters, it’s Spartan racers. I overheard more than a few conversations about electrolytes between exhausted walkers on the mountain, and the base was crawling with energy drink sales reps touting electrolyte content. The Spartan website officially recommends the use of salt pills, and the race is sponsored by at least one pickle juice company. I have no expertise here, nor even any anecdotes to relate; I’ve never staved off a bad cramp with a precisely timed mustard packet.
What I can tell you is that I started my morning off with a big mug of salty bone broth, and I ate a giant bowl of tuna avocado poke for breakfast, with extra macadamia nuts on the side. This was a low-carb meal packed to bursting with sodium, potassium and magnesium, which hopefully set me up for success during what would be a long, sweaty day. I can only assume that this was a far healthier start than a sugared energy drink would have been. (And if large amounts of raw fish seem like a curious pre-race meal, well, just remember that I’m the guy that lugged Spanish chorizo to the top of the Death March.)
Hydration is critical for all Spartan performers, and perhaps more so for those on a low-carb diet. I don’t have anything novel to say on the subject: I drank a ton of water, and you should too!
The Strategy
In theory, as a trail run punctuated with demanding obstacles, the Spartan race is almost ideally suited to the diabetic metabolism. Most people with Type 1 diabetes – and I am among them – see their blood sugar drop during endurance exercise, such as jogging, and rise during high-intensity exercise, such as weight lifting. What I hoped was that these two different types of exercise, aerobic and anaerobic, would to some extent balance out to keep my blood sugar relatively stable. I felt that a tight glucose range would be achievable.
However, having abandoned my smart phone, I decided that I wanted to go into the start of the race with a slightly elevated blood sugar. If I wasn’t going to have instant blood sugar readings, I wanted to have an initial buffer against hypoglycemia.
In a race like this, with swimming and dangerous heights and heavy obstacles, even mild hypoglycemia seemed a more significant hazard than the incalculably small amount of damage that a few hours of elevated blood sugars might do to my long-term health. I really did not want to first perceive the shakiness or wooziness of a deep hypo while I was climbing a cargo net high above the ground, or hoisting a sandbag over my head.
And so my aim was to start the race around 150 mg/dL. In my day-to-day life, I don’t tolerate a glucose level that high, and would immediately administer a correction bolus. But with the biggest workout of my life looming ahead, and a near certainty of falling blood sugars, I decided that 150 was ideal. It would probably allow me to complete several miles before I had to again worry about my blood sugar.
From then on, I’d pause to take occasional glucose readings, I’d try and pay attention to my body, and I wouldn’t be stingy with my sweets. I also theorized that a steady intake of small amounts of sugar would serve me better than a few large doses. The carb content of the nut butters would be helpful with this. I hoped to keep cruising in the 100-150 mg/dL area for the rest of the race.
I also decided that I would do my best to really pace myself. There was no sense in attacking the first half of the course only to fade and sputter in the second half. I held back on the early runs, jogging at a slow pace I knew I could sustain for miles at a time, and when I had to perform penalty burpees, I took it slow, saving my energy for the next leg. This is probably good advice for any racer of my experience level and ability, but I also figured it would help make my blood sugar shifts more predictable.
The Race
How did it work out? Pretty great actually. I spent much of the race in my ideal range, and didn’t once feel hampered by hypoglycemia.
It started off a bit shaky. I overshot my starting goal of a 150 mg/dL, and began the race at 180 mg/dL. By now there was nothing to be done about it – I was still fearful of using fast-acting insulin during the race – and it was time to run. But the buffer otherwise worked as intended: I was able to go several hours before breaking into my sugar stash.
I finally did so at the foot of the Death March, where I registered a 98 mg/dL. With the biggest cardio challenge of the day staring down at me I knew it was time to dig in. I ate 24g of simple carbs before attempting the climb, an enormous amount to take without a bolus, generally enough to spike me 100+ points, and more than I eat in most days. But in this situation it was a good call. I made it to the top without any issue, and my blood sugar remained relatively stable during and after the climb, proving that I needed every one of those carbs.
I spent most of the rest of the race in the 70-100 range. This was slightly lower than I had planned on. But because I felt great, and because my blood sugar was reacting in the ways that I had predicted, I felt more comfortable adjusting mid-race to prioritize a tighter level of control. I ate my sugar snacks every once in a while, especially immediately preceding the uphill climbs, going by intuition as much as by glucose meter. I still had a large stash of glucose ready in case I felt any symptom of hypoglycemia, which I never did.
The final stretch of the course was obstacle heavy, mixing aerobic and anaerobic exercise in the manner that I theorized would combine to create smooth glucose lines. I finished with a steady and healthy blood sugar.
The entire race took me about 7.5 hours. During the course of it I ate about 70 grams of carbohydrates, 50 in the form of energy gummies and 20 slow-acting carbs from the other food I ate.
All in all, I was very pleased with my performance and with my glucose control. I didn’t prepare perfectly, but even so my hard work and forethought allowed me to tackle this intimidating event safely. I hope that readers might benefit from my experience.
