I was a small sickly baby during the Cuban missile crisis, and my T1 mother briefly obsessed about stockpiling the obscure type of milk that was the only thing I tolerated at the time... (Guess she reckoned that there was no point to stockpiling insulin.)
I've still got my copy of the Government classic leaflet "Protect and Survive", which explains what to do in the event of a nuclear attack.
IN fiction, the standard scenario seems to be that you raid all the local and non-local pharmacies and then die after 6 months when you run out! But I'm not a particularly fast runner, so I reckon the zombies would get me first.
Interestingly, there was supposedly one man in the Channel Islands during the WW2 German occupation, where the limited insulin supplies meant that all the T1s died after the insulin ran out, who went off grid and starved himself and survived. Unfortunately I can't find the link, so I don't know whether he was early in diagnosis or maybe even a T2.... As I remember he was T1 and in the resistance....????