What to do about inexplicably high hemoglobin A1c

When hemoglobin A1c levels are higher than expected, given the self-monitoring blood glucose results, consider the following possibilities:

• Blood glucose levels that are outside the target range at times when self-monitoring blood glucose is not being done (e.g., postprandially or overnight)
• Technical problem with the blood glucose meter or strips or faulty technique
• Inaccurate data recorded in patient's logbook (if possible, use meter download or review meter memory to confirm)
• Low red blood cell turnover leading to a greater number of older red cells, which can occur with deficiencies of iron, vitamin B12 or folate
• Significant recent improvement in glucose, as the hemoglobin A1c reflects control over last 90-120 days
• Hemoglobin variants such as HbS (sickle cell trait) or HgF (fetal hemoglobin), which may lead some hemoglobin A1c assays to yield inaccurate results.
• Chronic kidney disease, because elevated urea can lead to false elevations with some assay techniques and dialysis may have variable effects on hemoglobin A1c