What are the reference ranges for Hemoglobin A1c (HbA1c) in mmol/mol?

From the Guidelines

The reference range for HbA1c in mmol/mol is typically categorized as below 42 mmol/mol for normal, 42-47 mmol/mol for prediabetes, and 48 mmol/mol or above for diabetes, with target ranges for diagnosed diabetes varying based on individual factors, generally aiming for below 53 mmol/mol for most adults 1.

Key Considerations

• For patients with diagnosed diabetes, target HbA1c ranges are individualized, considering factors such as age, comorbidities, and risk of hypoglycemia.
• The American Diabetes Association (ADA) recommends an HbA1c target of less than 7% (53 mmol/mol) for many nonpregnant adults, with higher targets for children, adolescents, and individuals with limited life expectancy or extensive comorbid illnesses 1.
• HbA1c measurements are a crucial component of diabetes management, reflecting average blood glucose levels over the preceding 2-3 months.

HbA1c Targets

• For most adults with diabetes, an HbA1c target of less than 53 mmol/mol (7.0%) is generally recommended 1.
• Less stringent targets, such as less than 58-64 mmol/mol (7.5-8.0%), may be suitable for elderly patients or those with comorbidities 1.
• More stringent targets, such as less than 48 mmol/mol (6.5%), may be considered for selected individuals, such as those with short duration of diabetes, diet-treated type 2 diabetes, and long life expectancy, provided this goal can be achieved without substantial hypoglycemia or other adverse effects of treatment 1.

Monitoring and Adjustment

• Regular HbA1c monitoring, typically every 3-6 months, is essential for assessing long-term glycemic control and adjusting treatment plans accordingly.
• The use of continuous glucose monitoring (CGM) and other technological advances can facilitate achieving glycemic targets while reducing the risk of severe hypoglycemia 1.

From the Research

Reference Ranges for Hemoglobin A1c (HbA1c)

The reference ranges for Hemoglobin A1c (HbA1c) in mmol/mol are as follows:

• Normal glucose tolerance: less than or equal to 40 mmol/mol 2
• Prediabetes/intermediate hyperglycemia:
  • 39-47 mmol/mol (5.7-6.4%) as recommended by the ADA 3
  • 42-47 mmol/mol (6.0-6.4%) as recommended by the Canadians and Europeans 3
• Diabetes: greater than or equal to 50 mmol/mol (repeated on a second occasion in asymptomatic patients) 2
• Age-related HbA1c reference ranges for patients with glucokinase mutations:
  • 38-56 mmol/mol (5.6-7.3%) if aged ≤40 years 4
  • 41-60 mmol/mol (5.9-7.6%) if aged >40 years 4
• HbA1c thresholds for identifying individuals at high risk of type 2 diabetes:
  • 39 mmol/mol (5.7%) as recommended by the ADA 5
  • 42 mmol/mol (6.0%) as recommended by the IEC 5
  • 44 mmol/mol (6.2%) as a potential threshold for identifying high-risk individuals 5