Hemoglobinopathy: Certain hemoglobinopathies, such as sickle cell disease or thalassemia, can lead to a low A1c reading due to the abnormal structure or function of hemoglobin. This is because A1c measurements are based on the average blood glucose levels attached to normal hemoglobin over the past 2-3 months.

Recent Blood Transfusion: Receiving a blood transfusion can lower A1c levels because the transfused red blood cells are typically younger and have not been exposed to high glucose levels for an extended period.
Chronic Kidney Disease or Nephrotic Syndrome: Conditions that lead to a shortened red blood cell lifespan can result in lower A1c levels because the average age of red blood cells in the circulation is younger.
Chronic Liver Disease: Liver dysfunction can affect the production of glucose and the metabolism of hemoglobin, potentially leading to lower A1c readings.

Severe Iron Deficiency Anemia: Although less common, severe iron deficiency can lead to a decrease in A1c levels. It's crucial to identify and treat iron deficiency anemia due to its significant impact on health.
Recent Hemorrhage or Blood Loss: Significant blood loss can lead to the release of young red blood cells into the circulation, which have not been exposed to high glucose levels, thus lowering the A1c.

Hereditary Spherocytosis: A rare genetic disorder characterized by the production of abnormal, sphere-shaped red blood cells that are prematurely destroyed, potentially leading to lower A1c levels.
Other Hemolytic Anemias: Conditions like hereditary elliptocytosis or pyruvate kinase deficiency can cause hemolysis (red blood cell destruction), resulting in a lower A1c due to the younger average age of circulating red blood cells.
Altered Red Blood Cell Turnover: Any condition that affects the lifespan or turnover of red blood cells can potentially alter A1c levels, making it a rare but possible cause of low A1c without diabetes.