Hi,
I would expect to see that for myself if I had wheatabix or Shredded wheat as it is mostly simple carbohydrate and will turn to sugar. I learned the hard way that it's not a great food for a type 2. I now have coffee, geek yogurt, flax and chia seeds with a few blueberries and it keeps my levels stable
There is a conflicting information between the formal medical advice given and the experiences of people here, let alone what you can find on google.
My simple view is to not eat white processed foods, wheat, rice, spuds are few and far between and head towards more veg, more salad, beans pulses, good quality meat and fats, not processed fats but things like avocado. All of these things have lower simple carbohydrate/sugar and a lower rate of digestion and a lower rate of energy release, this helps to manage your bg readings.
Would keeping a food diary in something like myfitnesspal for a few weeks be an option to show you what the breakdown of your diet is and then you could correlate this against spikes, you can eliminate pesky foods?
Ross