This is your body's warning that you are feeding it more than it can comfortably cope with. So stop doing that!
The easiest thing to cut down on, is usually carbohydrate and the very first suggestion is always to stop adding sugar to hot drinks. However - an acquaintance who we only usually see a couple of times a year, as we both have motorhomes and belong to the same 'camping' club so we're sometimes on the same rally and sometimes not - so we were literally sited next door to one another this partic year. My immediate reaction was Blimey (name)! You hardly resemble a prime suspect, do you? - not visibly overweight, never seen either of them eating sweets, not first in the queue for the biscuits when we had a Coffee morning, or the cake when we had an Afternoon tea, etc. So, asked her what she actually in truth, did eat, most days.
Started of with cereal and milk. So - try having a bit less cereal. You could try using a smaller bowl to have it in for starters, so it looks as full as the usual one, daft as that sounds, that can work. When you peel the spuds to have with your cooked meal(s) if it's boiled spuds and they're large 'old' potatoes, would you have, say, 4 pieces of spud each? Yes. Good, cut that down to 3, then. Have a bit more of whatever 'other' veg you're having so there's no visible empty bit of the plate. (and/or have 2 'other' veg instead of just the one) (and/or use a smaller diameter plate) If you usually have 'large' loaves - buy smaller ones. Use a slightly smaller serving spoon for eg rice/pasta so you still have the same number of spoonfuls of it. Just try doing that and see how you get on! Nothing drastic at this stage!
Next HbA1c test 3 months later - result back down in the 30s again.