From the Guidelines
An HbA1c level of 6.5% or higher is considered diagnostic for diabetes. This means that if your blood test shows an HbA1c at or above this threshold, you would be diagnosed with diabetes, as stated in the most recent guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus 1. HbA1c measures your average blood glucose levels over the past 2-3 months by showing the percentage of hemoglobin in your blood that has glucose attached to it. For context, a normal HbA1c is below 5.7%, while levels between 5.7% and 6.4% indicate prediabetes, which means you're at increased risk for developing diabetes.
The 6.5% cutoff was established because research shows that this is the level at which the risk of diabetes complications begins to increase significantly, as supported by previous studies 1. If your HbA1c is at or above 6.5%, your healthcare provider will likely recommend lifestyle changes including diet modifications and increased physical activity, along with possible medication depending on your specific situation. It's essential to note that a single test result should be confirmed with a second test unless you have clear symptoms of diabetes, as emphasized in the standards of medical care in diabetes-2020 1.
Some key points to consider include:
- The diagnostic A1C cut point of 6.5% is associated with an inflection point for retinopathy prevalence 1
- Point-of-care A1C assays are not sufficiently accurate at this time to use for diagnostic purposes 1
- The A1C has several advantages to the FPG, including greater convenience, since fasting is not required, evidence to suggest greater preanalytical stability, and less day-to-day perturbations during periods of stress and illness 1
- The diagnosis is made on the basis of the confirmed test, and if patients have test results near the margins of the diagnostic threshold, the health care professional should discuss signs and symptoms with the patient and repeat the test in 3–6 months 1
From the Research
Definition of Diabetes based on HbA1c
- The HbA1c level considered for the diagnosis of diabetes is 6.5% or higher, as recommended by leading diabetes organizations and the World Health Organization 2.
- This threshold is suitable to detect subjects with prevalent retinopathy, which is the most diabetes-specific complication 2.
- However, it is noted that the 6.5% threshold has mainly been brought about by convention rather than by having a consistent empirical basis 2.
Comparison with Prediabetes
- Prediabetes is defined by an HbA1c level of 5.7% to 6.4% or 6.0% to 6.4% 3.
- Individuals with prediabetes are at increased risk of developing diabetes, cardiovascular events, and mortality 3.
- Lifestyle modification and metformin are recommended as first-line therapies for prediabetes 3.
HbA1c Levels in Diabetes Management
- HbA1c levels are used to assess the effectiveness of diabetes treatments, with a goal of reducing HbA1c levels to less than 7% 4, 5.
- Different medications, such as metformin, sulfonylurea, pioglitazone, and sitagliptin, can be used to achieve this goal, with similar effectiveness in reducing HbA1c levels 4, 5.
- The choice of medication should be individualized based on cost, personal preferences, and overall treatment goals, taking into account the wishes and priorities of the patient 6.