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HbA1c Testing Frequency: A Review of the Clinical Evidence and Guidelines

Last updated: September 26, 2014
Project Number: RC0593-000
Product Line: Rapid Response
Research Type: Drug
Report Type: Summary with Critical Appraisal
Result type: Report

Report in Brief

Diabetes is one of the world's fastest growing chronic diseases. In 2011, there were approximately 366 million people with diabetes worldwide, and this number is projected to reach 500 million by 2030 — a projected increase of 50% in only 19 years. Wide fluctuations in blood glucose levels from untreated or poorly treated diabetes result in complications such as kidney failure, cardiovascular disease, blindness, and nerve damage. One test used to track blood glucose control is the glycated hemoglobin (hemoglobin A1C) test.

The hemoglobin A1C test monitors a patient's average blood glucose levels over a period of time. Patients with diabetes find this test more convenient compared with other methods for measuring blood glucose over the long term because it is quick, does not require fasting, uses only a drop of blood, and can be done at any time of day or night. And, if refrigerated, the blood samples can remain stable for over a week.

As the prevalence of diabetes increases, so does the amount of hemoglobin A1C testing. A review of the evidence on the effect of different hemoglobin A1C testing frequencies and of guidelines on the timing of testing will help inform treatment decisions for patients with diabetes.

A limited literature search was conducted of key resources, and titles and abstracts of the retrieved publications were reviewed. Full-text publications were evaluated for final article selection according to predetermined selection criteria (population, intervention, comparator, outcomes, and study designs).

The literature search identified 255 citations, with 5 additional articles identified from other sources. Of the identified studies, 24 were deemed potentially relevant. After screening the abstracts, 5 reports met the criteria for inclusion in this review — 1 rapid systematic review of the clinical practice guidelines, 1 randomized controlled trial, and 3 non-randomized studies.

Key Messages

  • For patients with well-controlled diabetes, hemoglobin A1C testing at three-month intervals appears to be as effective for maintaining blood glucose levels as testing at six-month intervals.
  • Guidelines recommend hemoglobin A1C testing every six months for patients with well-controlled diabetes and every three months for those with poorly controlled diabetes.


  1. What is the clinical evidence regarding different HbA1c testing frequencies for patients with type 1 or type 2 diabetes?
  2. What are the evidence-based guidelines regarding HbA1c testing frequency for patients with type 1 or type 2 diabetes?

Key Message

Although there was the suggestion of potential benefit to shortened HbA1c testing intervals for some patients in non-randomized studies, evidence from a randomized controlled trial indicated that clinical outcomes for well-controlled patients tested at 3- or 6-month intervals were equivalent. Studies demonstrated that adherence to guidelines was able to improve variations in HbA1c levels. Clinical practice guidelines generally agree that HbA1c testing every six months is appropriate for patients who are well controlled. For those patients that have poorly controlled diabetes or who are making changes in their therapeutic regimen a testing once every three months was advised.