And that reason would be? HbA1C is effectively a measure of the average amount of sugar that has been in your blood over the last couple of months. A spot sug

And that reason would be? HbA1C is effectively a measure of the average amount of sugar that has been in your blood over the last couple of months. A spot sugar level is the amount of sugar in your blood right now, and can vary a huge amount, depending on when you last ate, what you ate, and what exercise you have just done. It's less useful. You can do a fasting blood glucose, and a glucose challenge, but these tests are much more inconvenient for the patient. Outside the US, most testing has switched to HbA1C for these reasons.