Google the Newcastle diet.
Chips in broon sauce with broon ale?
I also find porridge spikes my blood sugars but a full English fried/grilled breakfast (no baked beans or hash browns) barely affects them. 🙂 The problem for me is I rarely have time to cook a breakfast in the morning, so I've not yet given up the cereal, which does my morning sugars no good at all.
Interestingly, I've managed to lose about 10kgs since I was diagnosed in March, without eating significantly less. I just eat differently... Ditching most of the carbs out of my diet has worked wonders on my waistline. A spot of additional exercise helps.
I don't deny the utility of restricted calorie diets as well; I do the 5-2 diet on & off, and it's always good for a kg/week for a few weeks, but damn it's hard to do consistently. Now that I've been moved from the 7th floor of my office to the 2nd floor (which is effectively the 3rd due to a mezzanine level), I'm using the stairs instead of the lift. Started today... ache like hell. By the end of the week I expect to be in agony, but noticably (to the scales, at least) lighter...