This is a good point to raise as it is a limitation to a looping system - there is only so much insulin you can subtract from delivery.
It does not not alarm - I think the only time there is an alert is when Loop is not connected and I’m not sure if that’s audible. I’m at a disadvantage bc I’m not a user and I haven’t had to pay close attention. That’s not completely true, actually. As a caregiver, I get alerts on Nightscout for highs, lows, and disconnected Loop, but there is no alarm for a predicted low. The user, of course, gets high and low alerts directly from dexcom.
However, you can see the expected low on the Loop graph, see that Loop has shut down basal and that it’s not sufficient to address the low and then decide to take action. I’ll have to ask Caleb - I don’t think it estimates an amount of carbs that will help, but you can input an amount and it will adjust the predicted bg to give you validation of the amount. You have to be attentive to do all this though. It’s not a “set and forget” scenario.