We overslept through a dexcom alarm and as result my 7 year old daughter suffered a severe low, it was a horrific moment that I hope I never experience again.
that has led me to build a gadget to make sure I never oversleep again. If anyone is interested please feel free to contact me. It is not cheap as it involves an ipad.
we now have a dedicated ipad that never leaves the room and is always plugged in. you connect the ipads headphone jack to a mini plug jack ($9) , you cut the ends off and connect it to an audio relay ($94). that relay is plugged into an outlet through a typical 24 volt transformer ($9). you also connect a loud pizzoni buzzer ($30) to the relay. When the dexcom goes off at your low setting the relay will receive that audio (ringer) signal through the headphone jack and converts/feeds 24volts to the pizzoni buzzer that wakes the hell out of you no matter how deep you sleep.
so all in all (except ipad) its $150 to make sure you dont ever oversleep.
It is basically as loud as a proper smoke detector. Any handy person can rig it, or if anyone is interested I could walk them through the process or do a video of how to do the connections.