Here are some things I have picked up about this in the last year...
The heart-healthy/eatwell plate/food pyramid advice seems (at least in part) connected to conclusions of the seven country study. This showed a correlation between a reduction in heart disease and consumption of whole grains. Since people with diabetes are at increased risk of heart disease, variations of this advice is then given to many/most type 2 diabetics. Some hear 'eat lots of starchy carbs at every meal' others 'eat some starchy carbs' still others 'eat a moderate amount of starchy carbs, but watch your meter'.
Part of the problerm with this is that people with diabetes have a difficult relationship with carbohydrate. We all need to treat carbs with a good deal of caution if our BG levels are not to remain dangerously high and/or erratic. The possible heart-health benefits indicated by the research may well be being completely overwhelmed by the additional risks involved in unmoderated carb consumption and high BGs.
Additionally the 'seven country' study is itself under question. Initially 20 or 21 countries took part, but results which did not fit the pattern were discarded. I've also read a conspiratorial whisper about the research being funded by a slightly under-performing US grain industry, but I don't know the truth of that.
Part of the problem with the advice is, of course, that all carbs (whether so-called 'starchy' or not) are turned onto glucose in the bloodstream. In fact our bodies are incredibly good at doing this. Eating glucose is obviously the fastest, but some supposedly 'complex' versions can be surprisingly fast. Some people will find (and everyone is different so there's no option but to carry out your own tests unfortunately, despite what your GP might suggest) that mashed potato or grapes will hit the bloodstream in a very similar timeframe while others will be fine with those, but have problems with others. Many T2s seem to find that an between and hour and two after eating is when their BG levels will peak.
For a general guide you can check the GI and GL of foods (glycaemic index and glycaemic load) but these are just average figures based on a sample of 100 or so, so there's no real guarantee that granary bread (or whatever) will behave the same for you.
At the end of the day, as others have said, the best bet is to get hold of a blood glucose monitor and test for yourself. You will soon find which foods you can tolerate and which cauuse you big BG spikes.
Mike