I have read on the forum here posts that imply each individual person has to work out what spikes their blood glucose and that you have to experiment with various foods yourself
I wouldn't put it quite like that exactly as the 'science' behind it is that very simply put, food with carbs in will cause your glucose levels to rise and food without carbs in won't so you have an excellent starting point. Now obviously as mentioned above, within that broad statement, some foods with no carbs but protein in will cause levels to rise as well in certain circumstances and other fairly complicated factors will affect levels too. So, what I'm saying is that it's not so much an individual having to work out whether bread, et al will raise them, you can pretty much rest assured it will, but it's that bread will raise some higher than others and some can tolerate it better. To all intents & purposes though, the obvious things that will raise our levels is universal, ie, pasta/bread/rice/potatoes and so on, whereas no carb stuff, cheese/meat/eggs and so on, won't. So, once you know the basics, people then start their experiments and that is where they can then work out what 'spikes' their glucose levels within the above criteria. For example, I might eat 2 slices of bread and be raised by 2 points, someone else (all things being equal) may shoot up by 4 points. Others may stay at the same level. I hope this helps.