I'm a practice nurse and diabetic specialist,
Pre diabetes HBA1c level is 43-47
Diabetes is 48 and above.
Unfortunately It's a fact that lifestyle, diet and obesity is the main cause for type 2 diabetes.
That being said - loosing weight and having the will power to cut out the sugary snacks and carbs is really really hard for many people. Food is addictive and it's hard to eat healthy.
Your husband needs to understand (and I'm sure he does) that diabetes is an absolute burden and causes lots of secondary complications later in life, and he can do something now to stop it from developing. Ask the practice to refer him to the "diabetes prevention program"
Low carbs, low sugar diet is key. Alcohol is a total waste of calories so cutting that down is also important.
Small changes - cutting sugar out of tea and coffee. Swapping to brown bread, smaller portions, bulk meals with veg, protein Keeps you full for longer. Don't even have chocolate and crisps in the house....... all just ideas.
One of my patients had great success with the "hello fresh" home delivery recipe boxes. Maybe give that a try if you are running out of ideas. Also the Mediterranean diet is also a good diet plan to look into, they have lots of recipe books on Amazon.
Hope this helps x