Tracking HbA1c Across A Year: The Table That Keeps Everyone Honest

The Table, Before Any Argument

Here is the whole method on one page: four rows a year, five columns, no software. The values below are a worked sample year, the same shape as the table that lives in my father's report file.

Every eAG figure in that table is computed, not copied from a chart: 28.7 times the HbA1c, minus 46.7, then divided by 18.016 for the mmol/L column. March runs 28.7 times 8.1, which is 232.47, minus 46.7, which is 185.77, printed as 186. December runs 28.7 times 6.9, which is 198.03, minus 46.7, which is 151.33, printed as 151. You can check any row on the HbA1c to eAG calculator in seconds.

Educational information only, not medical advice. The sample year above illustrates a record-keeping method. It is not a target path for any reader, and what a real table means belongs to the patient's own doctor.

How The Table Got Taped Into The File

The table exists because of an argument, a polite one, repeated at every family lunch for a year. Was my father improving? His memory said yes, warmly and in detail. My memory said the numbers had barely moved. My sister, calling from abroad, held a third position based on whichever single report she had last been sent. Each account quoted a real result. None of them quoted the sequence.

So I took a sheet of paper, ruled four lines across it, and wrote the columns you see above: date, HbA1c, eAG, and one note about the quarter. I filled in the two results already on hand and taped the sheet inside the front cover of his report file, where the next result would land beside the old ones whether anyone felt like comparing or not. Two entries in, the argument ended. Not because the news was good, but because the question had changed from what everyone remembered to what the rows said.

That sheet taught me the habit I now check myself against: memory rounds every number in the teller's favor, mine included, and the table does not. Four rows ended a year of family debate, and since then I treat any figure I cannot point to in a row as an opinion, including my own.

Reading The Four Rows

Read a finished year in two passes. The first pass follows the HbA1c column: 8.1, 7.6, 7.2, 6.9. Each step down is half a point or less, and no single step would have settled any argument on its own. Together they describe a direction, steady across four separate blood draws, and a direction is far harder to argue with than a result.

The second pass reads the note column against the numbers, carefully. June's row fell in the quarter the evening walks began. September's fell after the doctor changed a medicine timing.

The notes record what was different; they do not prove what caused the change, and I write them as events, never as explanations. A note column that claims causes becomes a story the family tells itself. A note column that records events stays evidence. The three-month reach of each result is what makes the quarterly spacing work at all, a piece of physiology I covered in Why HbA1c Covers Three Months.

A single result is a photograph. Four results are a direction.

Building Your Own Table

The build takes one sheet of paper and ten minutes.

1. Rule five columns: test month, HbA1c, eAG in mg/dL, eAG in mmol/L, and the note column. Leave the note column the widest space on the page.
2. Convert each HbA1c as the report arrives, never in a batch at the end of the year. Use 28.7 times HbA1c minus 46.7 for mg/dL, then divide by 18.016 for mmol/L.
3. Write the note within a day of the result, while the quarter is still easy to remember: what changed, what stayed, any illness or treatment in between.
4. Record a missed quarter as a row with a dash and its reason. A gap you can see is information; a gap you have closed up is a fiction.
5. Tape or staple the sheet inside the report file itself, not in a drawer. The table works because the next report lands next to it.

Keep the units in each column fixed for the life of the table. A column that begins in mg/dL must never quietly accept an mmol/L figure in its third row, because the year will later be read as one scale and a healthy 8.9 will file itself beside a worrying 160 as if the two were neighbors. If a report arrives in the other unit, convert it before it earns its row, and let the note column say that you did.

Testing pace sets the row count. The ADA recommends HbA1c at least twice a year for patients meeting their goals and quarterly when therapy changes or goals are missed, so an honest table gains two to four rows a year. A table with two rows a year still beats a memory with twelve opinions.

The Caregiver's Quarterly Routine: The Use Case

At home the routine now runs itself, and it is the routine I recommend to any family member who manages a parent's reports. The lab result arrives. Before it goes into the file, it stops at the kitchen table for five minutes: convert the number, write the row, add the note. Then the file closes.

On appointment day the file travels with its first page already summarizing the year, and the doctor spends the visit on decisions instead of archaeology. I read the sheet twice before each appointment, once for the row that moved and once for the row that should be there and is not, because the gap asks the sharper question.

The table also prepares the appointment in a second way. A row that moved the wrong way, or a gap where a test should be, turns into a written question on the spot. Half of The Appointment Questions My Family Now Carries were born as odd rows in this table. That is the deepest service the sheet performs: it converts a year of vague worry into four rows and two or three precise questions.

What This Table Is Not

Educational information only, not medical advice. A tracking table organizes results; it does not interpret them. Rows can bend for reasons that have nothing to do with glucose, including anemia and other conditions that shift HbA1c, and only your doctor can weigh a table against the full record. Keep the table faithfully, and let its reading happen at the appointment.