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  • Writer's pictureNatalia Roman Lopez

Pyreneean Trilogy: Aneto - Perdiguero - Posets

Updated: Jul 25, 2023

The Pyrenees is not a terrain for hares. It is the home to deer and mountain goats. Reaching its peaks requires large doses of orientation and, despite high-tech GPS watches, the best way to get started is through experienced fellow mountaineers. Good news: the human being prevails.

A kilometre can last 5 minutes... or 50. In these wild and rough Pyrenees, numbers do lie. Faced with this stark reality, the best thing to pack for the journey is patience - oops, did I leave it at home?

E ridge to Posets
The wild Pyrenees . © Jorge García-Dihinx

To understand the reasons that led me to dream of an imaginary line linking 3 Pyrenean giants - Aneto, Posets, and Perdiguero - we must go back in time; at least to a similar date in July 2021, when I linked Aneto and Posets by another faster but less logical route. Probably further back, to the summer of 1998, followed by the winter of 2000. Both mark the first contact with a valley - Benasque - that since then has occupied my days of wanderings and more than one night of dreams.

"I have learned to fear not only what is conceived, the idea, but also what precedes it or comes before it. And thus, I am my own pain and my fever." - Javier Marías, Your Face Tomorrow.

Little by little, I learned the recipe to face adventures of such an overwhelming size that one almost does not dare to express out loud. The recipe - not for success, but for getting started! - requires mountain experience, knowledge of the terrain and route, physical and mental endurance, and a mixture of desire and grit greater than the unforeseen events that may arise. Two more little things - perhaps the most important - a team to lean on and a cool head to make decisions 'in the heat of battle'.

Ultradistance running is a team sport!
Ultradistance running is a team sport!

What follows is the account of the 26 hours and 36 minutes it took me to cover the 70.3km +5620m linking the peaks of Aneto, Perdiguero, and Posets in the most logical and aesthetic way I drew in my head after years of Pyrenean exploration. In other words: do not do this at home.

Route: departure from Benasque -> Aneto via Coronas with descent via Saltarillo to Llanos del Hospital. Perdiguero via Remuñe with descent through the pass of Ubago to Refugio de Estós. Posets via La Paul col and subsequent E wall + ridge with final descent via Angel Orús hut to Eriste.


Benasque – Ref Coronas – Collado Coronas – Aneto – Ibón Salterillo – Besurta – Llanos Hospital (aparcamiento del vado).

It is well known that birds of the same feather, flock together. I'm talking about the motivated ones like Mariano, whom I met coming down from Posets (well, he was going up). Shared adventures have been a constant ever since. All it took was an audio message explaining my crazy plan for Mariano to confirm his availability and willingness to accompany me to the first giant: Aneto, the highest peak of the Pyrenees.

It is 21:45. Time for the traditional coffee that will precede a sleepless night. I am eager to get started and when the clock shows 21:59, I feel a rush as if we were going to miss the start of a race. What nonsense! Mariano and I head for the main street of Benasque and run the first 2k with the last lights of the day. Clear skies, warm temperature. I wonder how the dynamics of going together will play, considering we have different objectives: Mariano always ready to give me a hand; I focused on the here and now, but also with an eye on what awaits me beyond Aneto.

The profuse chatting puts us at the end of the Ballibierna dirt road in 1h 42' -almost 20 min faster than my estimation. Probably not the best news when you expect to be on the move for 24 hours. Mariano is worried about going too fast; I'm worried about the thirst. Up to this point my blood sugar has followed a pattern I know well from races that go out at night. Little by little it has risen from 80 to 130 mg/dL, despite not eating and only drinking water. My tendency would be to correct with 1u of rapid insulin. However, I decide to wait and see how it evolves once we get on the trails. I have reduced the evening basal insulin from 6-7u to 4u Levemir. In addition, I had a good entrecôte for dinner 5h before the start so that both the protein and the regular Actrapid insulin are already out of the system.

Our route up the South face of Aneto
Our route up the South face of Aneto

Unfortunately, my thirst has turned into 'African child belly' dehydration with the subsequent nausea. 'We know each other, my friend. But this time, I'm in the driver seat,' I tell it. I commend myself to the great Courtney Dauwalter and repeat to myself over and over again that it all passes, embrace the pain cave.

Now is when the teamwork begins. The night navigation turns out to be - by far - the most complex aspect of climbing and descending Aneto. We both know the route and are therefore fully aware of how easy it is to lose the trail. Once near the alpine lakes, following cairns at night becomes tricky. Fortunately, we are two motivated optimists. The important thing is not how many times you get it wrong, but how long it takes you to find again the right path. In the lower part of the forest, we draw some GPS lines for the memory and later laughter. We navigated the middle and upper lakes of Coronas with relative ease.

Night 'detours' making for memorable laughs

The snow never seems to arrive. With a blood sugar 'installed' in perfection (around 90 mg/dL) I decide to eat a bar (12g protein, 9g carbs) with 1u fiasp. Finally, we take the glacier path - still without snow - that leads to the pass of Coronas. However, in the high area we find ourselves climbing a chimney that does not match our memory of the area and, indeed, is to the left of the normal ascent. We must backtrack and cross a hard and steep snowfield. If we wait until we need crampons, it will be too late to put them on safely. Crampons, gloves, long sleeves, and focus.

See our mistake apporaching the Coronas col. Also, the difference between the rocky ascent and snowy descent.

What worries me most about the area are the rockfalls. Something we cannot control, but we can minimize if we move efficiently. In no time we are at the pass and breathe a sigh of relief. It is 3:20 am. We keep crampons on until the snow track stops and it seems to turn into a rock scramble. Strange, neither of us remember it that way. We remove crampons and, although further on we could progress on snow, we manage to avoid it and reach the summit on rock. The sky, of an undaunted black. Starry and windy night. Before reaching the cross of Aneto 3404m, the head is already planning how to manage the descent to the Ibón de Salterillo. Photo and message to Jorge: Summit 4am. Parking 6:30?

Aneto summit. 4AM
Aneto summit. 4AM

Climbing up we have located the track of those who go up the N face, which will be our descent. More direct than usual, but on perfect snow - neither too hard to make a fall dangerous, nor too soft to sink in and delay our progress. As we put on our crampons at around 3300m, I also measure my blood glucose (until now I had been relying on the Dexcom CGM sensor), and sure enough, when I go down, it goes up. To slow down the ascent, I inject 2u fiasp and finish the protein bar. The descent on the snow requires attention, but it's fast. I wear double light - head and chest - which helps to see the immediate and partially what is to come.

Here the downhill route towards Salterillo lake - the 'new normal' route due to the blank ice at the glacier.

Continuous snow - softer and softer - until 2800m. We remove crampons, and with them also goes the optimism. From this point to the junction with the path up to the pass of the Renclusa / down to Aigualluts, both navigation and terrain become annoying. Thanks to Mariano's good memory we go down in an infinite diagonal to the left. The first lights over the border with France give us a pink sunrise. The power of the headlamps (I carry two with their spare batteries) weakens, and I look forward to the moment when the natural light is enough to jump from stone to stone.

Map besurta, llanos del hospital
Last section before my frist crewing point at Llanos del Hospital. We had been moving for +9h.

We agree to go down through Aigualluts even if it means getting wet at the river crossing . Finally, Mariano pulls out of the hat a 'precarious' crossing over the ravine and we save 15’. Arriving at Besurta (7am), I don't need neither a sensor nor a glucometer to know that my hypoglycemia needs to be treated urgently. Nothing that a few gummy bears and a giant date can't solve. We continue jogging with joy along the GR-11 between cows towards Llanos del Hospital, how happy the morning light makes us!

Cannot wait for breakfast, lightening the backpack, putting on dry clothes.... Paradise!


Aparcamiento Vado – Remuñe – Ibon Blanco Literola – Perdiguero – Collado Ubago – Cabaña Turmo – Refugio Estós

7:30AM Knock, knock. Jorge opens his sleeping beauty eyes and we immediately get into action (although not in a hurry). All night in navigation mode has left the watch almost out of battery. Change of clothes, turkey and cream cheese sandwich with keto bread, spanish omelette, cookies... half an hour flies by. In a guessing exercise, I inject 3u Novorapid with breakfast. At the same time, it's time for basal insulin: 5u Levemir, instead of the usual 8-9u.

Traditional Spanish tortilla
Traditional Spanish tortilla. A day to indulge :-)

Full of optimism - and surprisingly physically fresh - at 8AM I say goodbye to Mariano - infinite gratitude - and Jorge - see you later, alligator - and calmly face the steep slope that joins the parking with the beginning of the Remuñe valley trailhead. Perdiguero is going to be my little private party. Turn on the volume! I notice that my body has gone into 'ultra mode' and luckily, I follow a steady pace that doesn't wear me out too much.

Valle de Remuñe
Valle de Remuñe

Breakfast insulin is taking its toll and, although the hypoglycaemia is never pronounced, I'm eating jelly beans for most of the climb. However, my continuous blood glucose sensor is giving low values by mistake. Thanks to the music and the beauty of this endless valley, I manage to distract myself from the beeping of the sensor alarms... I also take the opportunity to drink plenty (dehydration makes the sensor work worse) and dip my legs in every river, creek, and puddle.

Plenty of water at Valle de Remuñe
Plenty of water at Valle de Remuñe

After 1.5h following the orographic left bank of the river - which by then was still in the shade - I cross to the other side in the direction of the Portal de Remuñe. At times I doubt that the grassy path with great exposure - I have gone from walking sticks to gardening gloves - is the normal route. Still, I find it comfortable to progress, I'm going in the right direction, and gaining altitude - what else could I ask for!

On the grassy traverse

Higher up, a horizontal traverse leaves me on the path marked with dots that goes to the Ibón Blanco de Literola. Boulders and more boulders.

Finally, I reach the glacier lake after a short downhill and gain full view of the humongous pile of rocks leading to Perdiguero 'my god, what a motivation killer'. The wind, incessant. From my last time there, I remember this stretch so uncomfortable, and the summit so far away, that when I reach it I am convinced that it isn’t there!!!! Until I find the little stone with the writing 'Perdiguero 3222m' I don't believe it. Photo and funambulism to find phone network. Brief message: Summit 12:02. Punctual as a Swiss train.

Perdiguero summit
Perdiguero summit 4h after laving my crew

The Ubago pass makes it possible to join the Remuñe/Literola valley with the Estós valley. I find this seldomly travelled variant - I knew it only in ascent and the memory is already very blurred - misleading and tricky. I look and re-look at the GPS track and also at the horizon in search of cairns. Sometimes I see none, sometimes too many and in opposite directions. The progression becomes very slow. The Garmin battery is getting dangerously close to the single digit.

Larga subida por Remuñe al Perdiguero y directa bajada por Ubago al Valle de Estós
Long uphill through Remuñe to Perdiguero and direct downhill to Valle de Estós

The situation is starting to piss me off. With no clear path or certain direction, I move from stone to stone. So much balance game generates mental fatigue. I just want to get to the meadow, and then what? Fortunately, the watch battery lasts enough to put me on the right path that goes into the forest. From here I can almost see the Turmo cabin and I certainly feel the heat of the valley rising up like flames. Every river, a bath.

When I leave the forest, 2h30' have passed since the summit. I expected to be already at the refuge of Estós by now... however, I am still 4km away. I don't know if it is the anxiety to reach my longed-for refreshment, the fact that I am already in familiar terrain, or knowing that for Posets I can count on Jorge's help... I start running as if I had just left home. Under a blazing sun, I arrive at the Refugio de Estos at 3PM. I don't know it yet, but this totally unnecessary jogging is going to ‘gift’ me hours of suffering sooner rather than later.


Refugio Estós – Collado La Paul – Vira E – Posets – Canal Fonda – Ref Ángel Orús - Eriste

Our route to the last giant: Posets

I see a pair of arms like windmill blades greeting me from the terrace of the Refugio de Estós. There is Jorge, my faithful knight. After many hours in the solitude and intimacy of the remote mountains, it is always strange to get back in touch with reality and the humans that inhabit it. I find myself a little out of place among mountaineers drinking beer, agreeing on breakfast time, and talking about the next day's route. Thank goodness Nico - the Estós hut guardian - is looking out for us and our ridiculous requests... ice? Not above 1500m!

Eventually I 'wake uo', and wash my face and hands a bit to be able to measure blood glucose reliably, I inject 3u fiasp (it will turn out to be too many) and eat some ham sandwich, chips, almonds, cookies. In small quantities because of the overwhelming heat. Special mention to Nico's glass of milk. I don't know what happens, but the clock speeds up during the breaks. Soon 30 minutes go by, and I get the feeling of starting a race against the sunset.

© Jorge García-Dihinx
Heading into a rough afaternoon © Jorge García-Dihinx

It's hard for me to get going again, which surprises and worries me in equal parts. We cross the river and head that grassy half-slope that last September was full of cows (and cow shit). Today, we are greeted with a vegetation of about 1m high. I joke about going vegan... I don't think so!

Following Jorge's navigation guidance © Jorge García-Dihinx

Every step I take, a stroke of reality : as soon as I reach the middle of my zone 2, I find it hard to breathe. Pure agony. And the heat doesn't help. Autopilot: Jorge in charge of the navigation, visor on, short stride, and the only gear I have (we climb at about 400-450m per hour). After the first hour, I take out the calculator: if we have climbed 400m and the climb is about 1500m, we have 'only' 1100m left. Well, actually, the last 200m of rock, climb, and ridge don't count; so we have 900m left. Meaning, a couple of hours. He who does not find comfort is because he doesn't want to! If we didn't know the terrain, the math might even do the trick...

Ungratefull uphill to col de La Paul
Ungratefull uphill to col de La Paul
Glucosemeter used when in doubt!

And the Dexcom does not stop beeping every 5 minutes. At some point I notice symptoms of hypoglycemia that I treat with dried figs and glucose tablets. But there comes a point when I doubt the veracity of the sensor of the sensor values. The capillary blood glucose reading is 4.4 mmol/L (82 mg/dL) just after I have eaten some candy and a mini bite of Jorge's Snickers. I fear what's going to happen next - hyperglycemia on the verge - but I'm too sick of the T1D drama. Screw it!

Between silences that say more than any words, we spot the col of La Paul. It's a long way up on stony terrain. Jorge lets out his last 'it's still shorter to go down the way we came than to continue'. Y UN JAMON! (the panish equivalent of 'no way') I scream back - even if I don’t mean it. Meanwhile, the watch shows +5000m of elevation gain. A small morale booster.

When we reach La Paul pass we finally gain a complete view of the basin that will take us to the famous East wall with its 'magical' line. Unless you know where the corridor is located, the wall seems impregnable. My hope is to progress through the snow as soon as possible and get as high as possible with crampons. Afterwards, we continue on a horizontal path to the right looking for the tack – ATTENTION, VERY HAZARDOUS TERRAIN. Technically it is an easy climb, but on completely broken ground and with a void under our feet.

When we're just a few meters away from reaching the traverse, a snow patch hanging literally on the wall blocks our way. Half-jokingly, I tell Jorge to try passing between the snow and the wall. His joyful shouts upon reaching the other side confirm that it wasn't such a crazy idea. Relieved, I follow and take a bite of the snow patch. How delicious! But be warned, there's no time for daydreaming; for every quick step, there's a pause gasping for breath. Well, we knew what we were getting into, and yet, we went for it!

Approachin the chute leading to the ridge to Posets.
Approachin the chute leading to the ridge.

The ridge with the evening lights gains in beauty. Jorge captures these moments in photos and videos. I continue at my military pace: marching. It's one of the few times that fatigue suppresses the typical emotions that arise when reaching a dreamed-of summit - a trilogy of peaks in this case.

I appreciate Jorge's patience and apologize for making him suffer. Now, the only thing left is to descend from this Pyrenean monster. No matter how many hours it takes, I can already see the end.

We navigate the most technical part with a few slips. We manage to avoid the snow in the Fonda Canal on its left side. And upon reaching the GR-11 trail that connects the Angel Orús and Biados refuges, we know that getting to the valley bottom only requires endure. In our backpack, we carry the Lore of Endurance manual (pocket version because the hardcover one is heavy, haha).

But I didn't expect the visual and auditory feast that would accompany me as soon as darkness forced us to turn on our headlamps. Minutes before reaching Ángel Orús hut, I share with Jorge my surprise at seeing a perfectly aligned camp of igloo tents. Obviously, there is no such camp. I don't know what went through Jorge's mind (better read his chronicle).

At the summit, my blood glucose was slightly elevated and continued to rise during the first 500 meters of elevation loss. Betraying my intention not to correct blood glucose levels below 160 mg/dL while running (even though this madness isn't a race), I inject 2 units of Fiasp. The blood glucose starts to drop slowly until, just moments before arriving at the refuge, it plummets. I start sweating (thanks, adrenaline), my physical and mental coordination decreases. Dates, candies, cookies... and half a litre of milk offered by the kind guardian. I know I'm overdoing it, but... the milk tastes so good!

Last long downhill from Posets summit to Eriste village
Last long downhill from Posets summit to Eriste village

Now, all that's left is to descend along the trail to Espigantosa and then on the dirt road to Eriste. We turn on our headlamps, and a million insects rub their wings (??). We can't breathe or open our eyes. We move without light for moments, sometimes with the red safety light, and when it seems like there's less vegetation, with the medium intensity of the beam. Every time the trail passes close to the river, I hear music and conversations from a party very clearly. I know it's not real, but my senses deceive me wonderfully. At the same time, stumbling is constant, and each hit on my toenails makes me curse this descent.

Back on the road, the visual hallucinations are so creative that I feel like in a 3D movie. Christmas elves, glass jars with candles, Jorge holding a sign with a giant arrow... and in between, lucid thoughts like 'wow, this is what people were talking about.' I now belong to the club of unicorn spotters!

We arrive in Eriste, and there she is: Anita, aka sweetheart, aka the crew chief.

Both Ana and Jorge exclaim: "HOW UNNECESSARY!!!"

I, drunk with happiness, exhaustion, and colorful lights, conclude that if a 'because it's there' was enough to justify expeditions to Everest, it's more than enough to explain these trilogies of an adventurer wannabe.



Regarding glucose levels, I am satisfied with the outcome. However, T1D remains a continuous learning process where it is difficult to distinguish patterns from anecdotes.

Glucose 24h Dexcom CGM
Blood glucose during the 'run' (including mid-day measurement inaccuracies). Target 3.5-6.8 mmol/L

My key takeaways from 26h of glucose management:

  1. The reduction in basal insulin was very successful. Post-run, I gradually increased it by 1 unit per dose.

  2. Typical spikes in glucose levels linked to uphill/downhill switches occurred at Aneto and Posets. Rapid corrections managed to stop them, but the low rebound after 2 hours is dangerous. Perhaps a good timing to take in some carbohydrates (?).

  3. Certainly, regular insulin Actrapid is not needed to cover for protein on these mountain days. The metabolism of protein and possible gluconeogenesis occurs around 2-3 hours after meals (faster than the usual 5-6h), and Novorapid covers it well.

  4. At a certain point, the stress on the body generates a baseline of cortisol that perhaps could be counteracted with a basal boost. However, I have no idea when this phenomenon occurs, and the risk of hypoglycemia outweighs any experimentation.

  5. 'Not all carbohydrates are created equal’, meaning, carbs behave differently when correcting a hypoglycemia or when consumed with insulin. For me, what works best in both situations are: glucose tablets, dry figs, fresh fruit, candies (only during hypoglycemia!), potatoes, and rice. Bars like Mars/Snickers are disastrous. Food with gluten is very unpredictable.

Glucose levels in the 12 hours after finishing the challenge
Post-run 3 days blodd glucose. Perfection!

Once again, I confirmed how far one can go using our own fat (practically unlimited) as an energy source. In the case of a type 1 diabetic, a low-carbohydrate, high-protein, and moderate-fat diet (without the need to count grams or calories) provides the opportunity to achieve normoglycemia - even during exercise! It would be interesting to see the glucose curves of a non-T1D consuming sugary gels left and right...

Glucose (left) and ketone bodies (right) upon waking up the next day.
Glucose (left) and ketone bodies (right) upon waking up the next day. Date and time are incorrect.

Reducing carbohydrates in T1D is a THERAPEUTIC intervention that is rarely presented to the patient during their diagnosis and diabetes education. However, information about the 'associated' complications of this condition is abundantly available. The pitying looks are also there. Less paternalism and more scientific curiosity. Less conformity and more ambition.

It may be sweet, yes, but it's not worth it. TYPEONEGRIT

TYPEONEGRIT #letmebe83

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