We started on the dexcom before the omnipod. I cannot imagine life without it. It provides so much information, prevents countless lows. It really quiet that nagging voice in your head that wants to know where the bg is at and which way its going. You can take a reading at 90mgdl and know by the arrows whether you are going to stay around that number or if you could keep dropping.
Sites are less painful than the omnipod for my son. Though it looks a bit more intimidating, it is relatively painless. We use his arms all the time and have no issues with site. We started with the buttocks but it was not as accurate.
Not perfect but well worth it.
We have alarms set for below 100, fast drops (3mgdl+) and above 300. The alarms vibrate then beep which is not great for a parent of t1 toddler but probably preferable to a teen.
