Hi @jrussell88 ,
Welcome to FUD! Are you in the UK? We will have to get you properly introduced and put you on our map.
On the current omnipod, with the comms in the process of being broken, there is a theoretical possibility of someone being able to do something malicious. But it would take a lot of effort. I’ve been told, there are much easier ways to kill me.
Without knowing the pods’s ID, you would need a parabolic antenna to pick up the very limited range of communication from the PDM to the person’s pod. Then you’d need to be able to impersonate the PDM with that ID and send a command to the pod.
Do you know where they are going to be? Are you randomly walking around with your parabolic antenna hoping to find someone on omnipod? And they gotta stay in range for you to be able to intercept and also impersonate.
In theory, yes it is possible. But good luck with that attack. Much easier ways to do evil. I won’t list them here. 
On the new omnipod system coming out, it will use bluetooth. That would probably make the attack more difficult. Hard to say without seeing it.
Anyway, welcome here. Introduce yourself on the welcome-introduce-yourself-here page.