This daily variability is something that even my consultants appear unable to explain, and what people not on insulin will never fathom how difficult it is to manage blood sugar. Unrepeatable results. The story of my life. Every day I have learned to expect the unexpected - some days I'm more resistant to insulin, my immune system kills off the insulin or my insulin leaks out of the injection site, no two injection sites are the same, my injection site may have lipohypertrophy, at the end of the vial my insulin isn't as effective as the beginning, my insulin appears to stop working after two weeks, tiredness, feeling under the weather, extra exercise, emotionally stressed, the accuracy fo the reported carb content, portion size changes, time of day etc, etc.
DAFNE's preferred method is to do an adjustment (take a few more quick-acting units) with your next meal and don't sweat the highs.
Even though variability can be the elephant in the room, I still think recording your blood sugars and insulin doses and talking to your diabetes nurse and consultant a very helpful way forward.
My consultant, looking at my numbers, suggested that I mainly wasn't waiting long enough for my insulin to work before eating and that I needed to be prepared to change my background insulin by 10% depending on what's ahead of me in the day and how I feel. So I try to cut back or increase the split-dose basal a little based on how my numbers are trending, how much exercise I'm doing and how I feel.
The last thing I change is my quick-acting ratios, and usually after a few days of recording data, except when exercising, when I tend to halve the amount used.
I, like you, take a unit or two of quick-acting in the morning to combat 'feet on the floor' or 'dawn phenomena or just' the fact that I'm running out of background insulin by morning.
You are certainly not alone. Hopefully, they will release 'smart' insulin that works as needed in not the too distant future.