Today’s Paper
Health Newspapers

For how we live.

Calculators

A1c to average glucose converter

Convert HbA1c to estimated average glucose using the ADAG equation.

The percentage figure (NGSP units). Enter 7.0 rather than 53.

Estimated average glucose

154 mg/dL

In mmol/L
8.6
A1c in IFCC units
53 mmol/mol

Calculated in your browser. Nothing is sent to us or stored.

Estimated average glucose (mg/dL) = 28.7 x A1c(%) - 46.7, from the ADAG study.

What this does not capture

  • The ADAG equation describes an average. Individuals with identical A1c values can have genuinely different mean glucose, and the study's own 95% confidence intervals around each estimate are wide.
  • Anything that changes red blood cell lifespan distorts A1c — anaemia, haemoglobin variants, recent transfusion, pregnancy, chronic kidney disease.
  • A1c reflects roughly the preceding two to three months, weighted toward the most recent weeks. It cannot show variability, and two people with the same average can spend very different amounts of time high or low.
  • This converts a number. It does not tell you whether that number is appropriate for you, which depends on age, comorbidity, hypoglycaemia risk and treatment.

What the conversion is doing

A1c measures the proportion of haemoglobin that has glucose attached to it, which accumulates in proportion to how much glucose the blood has been carrying. The ADAG study put continuous glucose monitors and frequent fingerstick testing on 507 participants across three months and fitted a linear relationship between their measured mean glucose and their A1c.

That fitted line is the equation used here. It is a good description of the group and an approximation for any one person.

Why individual variation matters

ADAG reported confidence intervals around each estimate that span a clinically meaningful range. Two people at the same A1c may have mean glucose values far enough apart to matter for treatment decisions, which is part of why continuous monitoring has displaced A1c as the guide for people using insulin.

Time in range and glucose variability capture things A1c cannot, and current standards of care treat them as complementary rather than interchangeable.

Sources

  1. Translating the A1C assay into estimated average glucose values (ADAG study) — Diabetes Care
  2. Glycemic Targets: Standards of Care in Diabetes — American Diabetes Association

Related