Which condition can falsely lower hemoglobin A1c levels?

The condition that can falsely lower hemoglobin A1c levels is chronic hemolytic anemia. In chronic hemolytic anemia, there is increased destruction of red blood cells. Since hemoglobin A1c reflects the average blood glucose levels over the past two to three months by measuring the percentage of glycosylated hemoglobin in red blood cells, a decrease in the lifespan of these cells, as seen in hemolytic anemia, results in fewer red blood cells available for the formation of glycosylated hemoglobin. This leads to a misleadingly low hemoglobin A1c result, indicating better glucose control than is actually the case.

In contrast, conditions like chronic kidney disease can actually lead to elevated A1c levels due to alterations in the metabolism of glucose and red blood cell characteristics. Diabetes mellitus typically results in higher hemoglobin A1c levels as it reflects poor glycemic control over time. Hypertension, while a significant health condition, does not have a direct impact on hemoglobin A1c levels in the same way that chronic hemolytic anemia does. Thus, chronic hemolytic anemia is the clear condition that can interfere with accurate A1c measurement by lowering its value.