Although we are all different and you are taking exercise, your carb intake is twice what I could ever manage and have single figure BG levels.
I have read that the Gliclazide forces insulin into your blood, but it can be erratic, so you can have lows and highs due to that -so care needs to be taken if you do reduce the carbs, or miss a meal, as you can go low.
I found that it was the rapid changes in BG which made me feel unwell - I tested a few of the foods which caused weight gain and found they were exactly those which caused my BG to alter quickly, though in my case it was upwards at a great rate and down again painfully slowly.