HbA1c Range for Prediabetes

Definition and Diagnostic Criteria

The American Diabetes Association defines prediabetes as HbA1c levels of 5.7% to 6.4% (39 to 46 mmol/mol) 1, 2, 3
The American Diabetes Association also defines prediabetes as fasting plasma glucose (FPG) of 100 mg/dL to 125 mg/dL (5.6 to 6.9 mmol/L), also known as impaired fasting glucose (IFG) 2
The American Diabetes Association defines prediabetes as 2-hour plasma glucose during 75-g oral glucose tolerance test (OGTT) of 140 mg/dL to 199 mg/dL (7.8 to 11.0 mmol/L), also known as impaired glucose tolerance (IGT) 2

Individuals with HbA1c 5.7% to 6.0% (39 to 42 mmol/mol) have a 5-year risk of developing diabetes ranging from 9% to 25% 4, 5
Individuals with HbA1c 6.0% to 6.4% (42 to 46 mmol/mol) have a 5-year risk of developing diabetes ranging from 25% to 50%, with a relative risk approximately 20 times higher compared to those with HbA1c of 5.0% 4, 5

Baseline HbA1c is a stronger predictor of subsequent diabetes and cardiovascular events than fasting glucose in community-based studies 2, 4
The risk of progression to diabetes follows HbA1c levels as a continuum, with higher values associated with disproportionately greater risk 1, 4

The risk for developing diabetes follows HbA1c as a continuum, becoming disproportionately greater at the higher end of the prediabetes range 2, 4
More intensive follow-up and interventions should be considered for those with HbA1c levels above 6.0%, who are at very high risk 4, 5

The American Diabetes Association recommends testing for prediabetes in adults who are overweight or obese (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) with one or more additional risk factors 6
The American Diabetes Association recommends that for all people without risk factors, testing should begin at age 45 years 6
The American Diabetes Association recommends that if tests are normal, repeat testing at minimum 3-year intervals is reasonable 6

Individuals with HbA1c of 5.7-6.4% should be informed of their increased risk for diabetes and cardiovascular disease 4