Dead Legs after regimen change?

OK a little background. I’m a type 1.5(LADA) been very active running and cycling most of my life and over the past few years have run 2 half marathons numerous 5K and 10K’s 5 milers. This past Sunday was my second Broad Street Run in Philly (10miler) I’ve been on track to run it at a 7:00 pace. However 3 weeks ago my pancreas finally gave up and I was switched from the novolog/metformin/victoza therapy I’ve been on since January to lantus/novolog/metformin. I was able to get a few longer runs (11 and 7)miles in on this therapy and while keeping my pre-run and during run nutrition the same as I was planning on for race day maintained the same good numbers I was seeing on the old therapy. However I had noticed that my last tempo run before the race my legs felt dead and I couldn't get closer than 30secs a mile to goal pace no matter how hard I tried to push my legs just wouldn't respond, my heart rate stayed about 15bpm below threshold confirming my legs would only give about 80-85%. I just chalked it up to needing a rest… But the same thing happened during the race and I ended up finishing 4 minutes slower than my goal. The weird thing is it seemed like I built up lactic acid from the start, I don’t think I had made it more than ¼ mile and my legs were burning like I had been running threshold pace for an hour already. Any ideas? Could I need more or less insulin? My normal AM ration is 1:6 but before workouts like that I go with 1:15 2 hrs before and then take an additional 20-25g of carb about 30minutes before the start and that seems to keep me starting around 125 and in the 80-100 range for the duration of the run.

Wow, I just noticed this (May 7 was during my post-injury phase, when I was super bummed out, still, excuses are for losers!!). Tht's great data that you're accessing. Very precise and to the point. I don't know anything about met/vict. From what I've read, I'd blow off metformin and just go w/ insulin but I also "cheat" and have a pump. What was your BG doing during all that? I try to get my BG ok and run but I've had some issues w/ cramps too.