I've been using the Nano since February this year (and with Dexcom) and I get a reaction from the adhesive so use a HyperFix like tape as both an underpatch and overpatch to ensure the Nano stays attached. I can only have it attached for 2 days and not 3 due to my skin's reaction.
That said I...
I used to suffer horrendously from the Dawn Phenomenon (which is what you're experiencing by the sound of it). In my case the meals I ate and at what time didn't make an appreciable difference. The one thing which resolved the DP for me was changing from injections to an insulin pump 10 years...