Well done on the 5.9 waking reading. That's really good! Now take a deep breath make yourself a nice cup of tea/decaf coffee and try and do something else which will make you feel good. Above all do not look at the dexcom until lunch. Looking at something not moving will stress you which will in turn contribute to keeping your levels above where you want them. It's an unfortunate vicious circle.
Then write today off as a bad one and focus on looking at the patterns before you make changes.
Is your basal right? Your needs will start to increase at this point and you might want to experiment with some temp basals to see how much you need to increase by.
Is your carb ratio right? Your resistance will also start to be increasing at this point so you may need to make alterations there.
@azure 's advice is to eat the same thing 3 days in a row to check if it is correct. I'm afraid I tend to get bored but do stick to something I can very easily measure when checking my carb ratios.
Are there parts of the day where you're more insulin resistant than others? Mine has always been the morning.
How long are you pre-bolusing before a meal? Have a look at the dexcom and work out where the trend starts to come down and then you can calculate how long this should be.
Split bolusing? I find this helps with some meals even if there's only 30 mins in between. It's essential for me for big meals.
Are there are other external factors which could be affecting your readings? A cold (even a slight one), or other infection, stress at work or from other factors, sudden changes in temperature, a canula sited on a capillary (I find this really delays absorption).
I tend to low carb when everything is out of sync and do it more when I'm pregnant as I get much less of a spike with it. However, you have to remember that not all low carb food works the same way and supposedly 0 carb may not be treated by your body as such particularly if you low carb a lot.
Also you mentioned that your DSN said your readings are not in range when you thought they were. Why is that? I was told by my consultant last time that even if I might be getting slightly higher readings in the permitted range, the fact that I was centring them over a smaller range and avoiding bad hypos was far better.
You will get there. It takes time and effort but you can do it.
