I'm afraid that I totally disagree. I find a glucose monitor very helpful. If I am worried that I have had too much carbohydrate, I can measure my blood and take steps to reduce my glucose levels.
When I say take steps, I do mean that literally. I go for a brisk walk and the glucose comes down quickly.
HbA1C measures the average glucose levels over a 3 month period. That doesn't take into account spikes which can be quite harmful.