Does smoking marijuana show up on an hba1c test?

No, tests glucose. The hemoglobin A1c test is specifically looking for the percentage of hemoglobin with glucose attached to it. If you are smoking marijuana it will have no effect on the hga1c and only a test to specifically detect cannabis will show that chemical.
No. Hga1c tests are to check the effectiveness and compliance with medication in diabetic patients. They have nothing to do with cannibus or thc.
No. The technician time and testing materials differ when looking for A1C levels . In many states it is also illegal for the to look unless you have signed a waver for drug testing ahead of time.