We don't use Apple's iCloud. There's no need to.
As long as you sync inside SeriousMD, your data is already backed up.
In the case that you lose your phone or upgrade to a new one, you simply have to download SeriousMD again from the AppStore and log in with your username and password. Your data will be there.
You can actually test it out by using the web version of seriousmd. Just log into your account at www.seriousmd.com and you should see all your data there as well.
We recommend that you check your status on the bottom status bar of your SeriousMD app. It should say "SeriousMD is up to date" if it's completely backed up. If you use SeriousMD offline a lot, be sure to turn it on when you have internet so it can back up your data.