Welcome to the forum.
A prediabetes diagnosis is basically a wake up call to make some life style changes, getting more exercise if you can and making some dietary changes to reduce the amount of carbohydrates in your diet, this will help in losing weight if needed.
Some modest changes are probably all that is needed, cutting out cakes, biscuits and sugary drinks including fruit juice and reducing portion size of other high carb foods such as potatoes, rice, pasta, bread, breakfast cereals, pastry and tropical fruits such as bananas, mango, pineapple, grapes and look at alternative drinks instead of beer if he drinks that.
Basing meals on meat, fish, eggs, cheese, dairy with lots of veg and salads and fruit like berries.
Some things ca be had but better kept as treats rather than the norm like traditional puddings and chocolate.
Have a look at this link for some menu ideas and recipes for low carb meals.
lowcarbfreshwell.com
I found the principals in the link very easy to adopt and it is my new normal way of eating. My other half was very supportive in it and we basically have the same meals, he just has a few extras.
