Welcome Simonkit.
As another person who developed type 1 diabetes as an adult, aged 30 years, some 17 years ago, and had no intention of stopping hill walking, perhaps I can help. In fact, I remember asking DSN at hospital in West Mildlands where I was diagnosed about hill walking, but she just mentioned her version of gentle rambling, which wasn't what I meant at all. As there was very limited internet in those days (mid 1990s) I had to work things out for myself. Initially, I was put on bimodal insulin, which was pretty impractical, but after a trip to Belgium with a friend who was training to be a midwife, spoke with her mother, a pharmacist in Tasmania, who posted me a photocopy of an Australian pharmacy journal about basal bolus / MDI (Multiple Daily Injections) and I haven't looked back. In that first year, I climbed 2 of 3 Peaks of Yorkshire Dales with different friends, led an expedition of teenagers to Costa Rica, then started MSc in London, so not much hill walking, until next summer when I went to Northern Ireland to do my research project.
Briefly, what I have found is: if I know I'm going hill walking next day, then I reduce long acting night before by approx 25%, reduce in morning too (I take my long acting Humalin I twice a day, which I find more versatile), plus reduce short acting dose for same amount of breakfast (or eat more breakfast - depends on food availability, appetite etc). If hill walking happens unexpectedly, then I eat more. I always carry a combination of sweets (jelly babies / soft sweets / mints etc - whatever is on offer at shop), muesli bars, squeezy pouches of fruit (emergency rations, long use by dates, more robust than fruit such as bananas), dried fuit, normal food eg sandwiches, pork pies, crisps etc. For drinks, I often carry 2 bottles eg 1 flask of hot drink and 1 of cold, 1 of which contains sugar, the other sugar free. But equally, one of the pleasures of hill walking is drinking stream water, and I still do that, which means I don't have to carry much water in some areas. That's particularly important if you're carrying heavy kit - I only use a pocket digital camera these days, but marshalling on mountain marathons, adventure racees etc often means carrying tent, stove, food for up to 3 days, controls to put out / collect, so weight is an issue sometimes. You're right that sometimes you have to get some carbohydrates into yourself before heading up a slope - so always have some things in pockets (in trousers / shorts / jackets / rucksack belts etc) that you can reach without having to take off rucksack. After hill walking, I find I needto reduce long acting doses for at least 24 hours after, longer for more energetic / longer exercise.
Don't worry that a pump is essential - many people do find it necessary, but many of us manage fine with basal bolus / MDI regime.
Mountains for Active Diabetics (Facebook group) is also very good for practical answers from people with diabetes who love being active in mountains, in addition to Runsweet.
Hope that's enough to get you started. Just to reassure you, you might like to look at
www.howfast.org - James Thurlow has just run across Coast to Coast, east to west in just under 4 days, less than 2 years since he got type 1 diabetes in his early 40s.
