Can eating before a hemoglobin a1c blood test make the levels higher than they really are?

No: Hemoglobin A1c is a test used to measure the sugar content in your blood that has occurred over the last few months. By eating before a blood sugar test (usually done by finger prick) you can elevate the sugar levels in your blood, but this won't immediately change your hba1c. Hba1c comes from a build-up of "glycated hemoglobin" in the red blood cells over their life cycles, about 120 days.

No: Remember we are checking how well your diabetes has been controlled in the last 2 to 3 months - not a snapshot fasting blood sugar test. The glucose in our body is binding steadily to hemoglobin in red blood cells. The a1c test is used to measure how much glucose is in the plasma part of blood. So any immediate changes in blood sugar with eating are not important.