I’ve sold some Dexcom supplies myself, and I found that the best option by far is
Sell test strips through Diabetic Exchange USA. They specialize in helping people sell diabetic supplies, so you know you’re working with a service that’s reliable and understands what you need. The process is simple: you submit your supplies, and they handle all the logistics like shipping and payments. You also get a good price for your items, which is always nice. Their customer service is super responsive, so if you have any questions or concerns, they’ve got your back. Highly recommend giving them a try!