My dad has been diagnosed with type 2 diabetes and is currently on oral medications. He got a blood glucose monitor a couple of weeks ago and has been checking when he gets up, two hours after lunch, and two hours after dinner. His readings have been from 120 to 220 mg/dl [6.7 to 12.2 mmol/L]. He went to the doctor yesterday and his A1c was only 5.2. Does that seem low considering his readings? What other explanation could it be?

There are several possible explanations for a normal A1c with some blood glucose tests as high as 220 mg/dl [12.2 mmol/L]. It could be related to how the test was performed: was it done by a laboratory, office equipment such as a DCA 2000 or an A1cNow? Or, it could be that your father has certain blood problems, such as sickle cell and tallisemia, that can affect the A1c. Furthermore, the A1c is not a reflection of a simple mean of glucose levels, rather it is an arithmatic mean where the most recent glucose levels impact the glucose levels more strongly than those that occurred distantly. The A1c reflects about 120 days of blood glucose levels. You indicated that your dad had been measuring his blood sugars for only a couple of weeks. The 5.2 A1c showed that he had pretty good control for several months.

JS