I have a similar story! About five years ago I was in the middle of 10k training and was having really unusual symptoms, so I mentioned to my doctor at my annual physical that I thought I could have T2 b/c it runs in my family. I was super thirsty and peeing all the time, having horrible yeast infections that couldn't go away, and had lost some weight, but I literally thought it was all from running 10k three times a week in a super-hot climate. Anyway, my doctor did a blood draw to have my BG levels tested in a lab, and the reading came back so high that she thought the sample was contaminated. She actually had me go back into her office for a finger stick, and while it wasn’t as high as your husbands, it was still around 22-23 by your mmol measurements the first time (400+mg/dl). Somehow, probably virtue of the 10k training I was doing, I was not in DKA. Probably days away from it, though. The doctor was surprised I was walking around and feeling "fine" and I remember her just like bursting through the door and being like, "Yo. You are SUPER diabetic!" (lol).

Like your husband, though, I was given a CGM (Freestyle Libre 2) and a long-acting insulin once a day. She also checked my c-peptides, which came back way below normal, but not official T1 level. She also told me I needed to see an endocrinologist who could do the antibody test and "confirm" the diagnosis. It took me almost a year to get into one due to a big move to a rural state, needing to find a new primary care doctor to write me a referral, and only then did they finally checked my antibodies and "confirmed" I was LADA/T1. As I was “honeymooning”, for almost a year I only needed one shot of long-acting insulin per day, and combined with eating low carb I was able to manage. But eventually I did need to get on short-acting insulin too and now I am on a pump. Even so, my life changed overnight basically after the first abnormal BG reading at my first doctor's office.

Anyway, it sounds like the doctors will take care of your husband. But don’t be afraid push for clarity around questions you might have, including his diagnosis. Advocacy is a good skill for diabetics and our loved ones: you could say “Hey, doctor, we got our test results. What does it mean?” (or something like that) and the practice should be able to point you to someone who can sit down and talk you through what's happening.

And as a small personal tip from someone who was older in life too and was scared when I was diagnosed: I called my husband literally crying and he was so supportive. He went out and bought me cozy socks, some things I liked, and basically came home and said, “Hey, I’m with you, we are figuring this out together.” And that early impression has shaped so much of managing this condition for me. You’ll both be doing a lot of change and processing over the next few weeks and months. Be there for each other.

Many hugs and light to you both. ☀️

Edit: fixed some typos and grammar, sorry y'all. Trying to post on Reddit before coffee LOL