Hi and welcome. As you'll see from the other posts you are far from being alone, and lots of lovely people on here to help. Having a think about cutting down sugar and increasing exercise is a great start, do ask questions if you have them.
Unless you are eating a lot of sugary things then you might need to reduce starchy foods too, or you might prefer to cut back on them and have the sweet things. The problem we have is with the carbohydrates, sugars and starches in equal measure - they both end up in our bloodstream causing problems.
One of the biggest questions when being told you are at risk of diabetes is usually ‘what can I eat’ and while there are obvious things like cakes, biscuits, sweets and sugary drinks that you will be wanting to cut out straight away, you might be surprised how much *all* carbohydrate affects your BG levels, including rice, pasta, potatoes, bread, pastry, grains, cereals and many fruits. It’s not that you need to avoid these things entirely... just that your metabolism is beginning to struggle to process them, and with a little moderation and portion control you stand every chance of avoiding a full-on diabetes diagnosis.
You might find it helpful to keep a food diary for a week or two, noting down exactly what you eat for each meal and snack. Be honest! And if you can jot down the amount of carbohydrate in the meals/snacks too you will have a good indication of the things which are asking your metabolism to work extra hard.