I live in an area with very poor internet connectivity and makes using Cloud application not an option. I am running Lightroom 5, my questions is there a DVD upgrade available for Lightroom 6?.
No, sorry - Adobe is not offering it via disc or DVD... But here's one possible solution:
If you can access a computer with a faster connection - even if only for a short time - then you could use the Lightroom 6 direct links to download an offline installer, and then transfer that file to your desired system(s) using a USB flash/thumb drive. Then install it and away you go.
Installer size is about 750 MB.