If your husband is losing weight without trying, it does sound as though he may have been misdiagnosed and is really LADA - that's basically the same as type 1, it's just that type 1 usually starts very rapidly but LADA starts gradually.
It sounds as though your GP is on the ball, as Lin said, so hopefully the investigations your husband has been referred for will include tests for type 1. If not, then it is worth his asking (or politely insisting!) that he be tested for this - as
@Leadinglights says, a lot of GPs think only children get type 1, whereas actually quite a high percentage of people diagnosed with type 1 are over 21 (I was 44). The tests he would need are a GAD antibody test and ideally a C-Peptide test.
In the meanwhile it is worth his trying to cut out some carbs, because whichever type of diabetes he has this is going to help (in the long term if he has type 1 he will be able to eat some carbs, with insulin to balance them out, but without insulin a lot of carbs will make him very ill - if he does have type 2 then he'll need to cut down on carbs anyway). Don't forget carbs include starchy foods like pasta, rice, bread, and cereals as well as sugary foods - and also fruit - a lot of people think eating lots of fruit is healthy, but it's not if you're diabetic.
Please try not to worry about the possibility of his having type 1, because it is very easy to treat and if that is what he has he will feel a whole lot better once he's on insulin! But do keep an eye on him and if he starts feeling (or being) sick, having stomach pains, and/or his breath starts smelling of pear drops, take him straight to A&E, because those are signs of Diabetic Ketoacidosis (DKA) and that is an absolute emergency.