Porridge is normally good but many people do have problems with it. I guess it depends on how it is milled. I always have porridge and it doesn't cause too much of a rise in BG, about 0.5 mmol/L after 2 hours. It used to give me a rise of 2.0 mmol/L but, after having lost weight and after having generally got my BG levels down, it is now much better. I also do 6 or 7 mins exercise after about 1 hour. If I have a very early breakfast and go back to bed, it will still give me a 2 rather than 0.5 rise. I guess I need the blood pumping a little or it settles down in me and provides me with nourishing glucose for several hours. I have it with almond milk and truvia. If I used skimmed milk, the rise is slightly higher.
It's worth sticking with and trying to find a combination that works for you because it does help keep you going until lunchtime.