It’s an interesting topic, and one that I think can easily get overlooked. My current partner knew me for a year before we started dating, so she was well aware of my diabetes which made things a little easier.
I’ve personally always felt it’s best to be upfront about it in a dating context, not that I’ve ever really felt like it’s something to hide, but in my experiences it’s often always come into the conversation relatively organically. Whether that was the first date or a few dates in. Regardless of that, when they eventually come over to your house, or vice versa, it becomes a bit harder to hide it. I always found it much easier if I’d spoken about my diabetes during conversation over dinner, or beer or coffee or whatever it happened to be, rather than waiting until the awkward moment when I just whip out my insulin or glucometer and they look at you weirdly.
One thing I used to consider as well was if it felt weird talking to them about it, or they weren’t interested, then maybe that was a sign that things wouldn’t work. It’s definitely important to be able to have a partner you can open up to about your diabetes with!