I think it's a great idea! Sounds like running is giving you physical and mental benefits so why not continue.Now I got this crazy idea. What if I ran a marathon in 2020, when I turn 50?
T1 aside it's a hell of a tough challenge for anyone. But if you've recently done a 10k if you can keep building up slowly, maybe a couple of half marathons in the autumn, then a spring 2020 marathon is a realistic timeframe to aim for.
Key thing is when you're getting up to half marathon and longer distances is fuelling, plus then for us T1s getting the insulin right. But you've a year to train and practice. A nice side effect I found is that in general your day to day and like for like insulin requirements lower. Certainly after those long training runs and the marathon itself in those couple of days or so afterwards it's almost like having a free pass from T1... while obviously not stopping insulin, I can lower amounts and eat like crazy and bg numbers stay good!
Might be useful...
http://www.runsweet.com/diabetes-and-sport/marathon-running/
I've run marathons in my 40s and am T1 for reference. Why? It was more of a mid life crisis rather than a T1 crisis that made me start