Yeah, I agree with those above - make sure his own production of insulin is being tested, the easiest and cheapest I believe is the C-peptide test route, and that can be pretty quick - as quick as your lab is with blood lipid tests. Get your doctor to explain the results to you. (It's about numbers and thresholds and so on.)
As your husband,
@Susie1804 , is very physically active, make sure he is getting plenty of protein and healthy fats in his new low-carb diet, if he has in fact lowered his carbs, so he has enough fuel to keep active. He may go through a rough adjustment period if he has been consuming a lot of carbs previously (which is the modern norm), and his diabetes is in fact type 2 insulin resistance based diabetes. But your medical professionals should be following up/properly checkng him for anti bodies or failing producing his own insulin (which would mean he is a type 1 or type of type 1).
He, and you, will be going through a steep learning curve about different types of diabetes, and finding out which one he is, and working your way through the dietary advice - all really big things, imho. And he is probably in some kind of shock? Many of us have been there, so we understand.
Tell us when you know what type he is, and we can suggest great websites and books, apart from this wonderful organisation.