What Is Hemoglobin A1C?
Hemoglobin is well known as the iron-containing metalloprotein found in red blood cells that helps transport oxygen in the body.1 Hemoglobin that has become glycosylated, or coated with glucose, in the presence of elevated intracellular glucose levels is commonly referred to as hemoglobin A1C.2
What Is the A1C Test?
The A1C test reflects the average glycemia over approximately 3 months and is used as the primary tool for assessing glycemic control and as a strong predictor of future diabetic complications.3 The American Diabetes Association (ADA) recommends testing A1C levels at initial diabetes assessment and routinely every 3 months to determine whether glycemic targets are reached and maintained in diabetic patients. The test requires a blood sample and is usually analyzed in a laboratory.1 The test will give its results in percentages, which corresponds to the average glucose levels experienced over the past 90 days.1,4
|Relationship Between A1C and Glucose Levels|
|A1C %||Estimated Average Glucose (mg/dL)|
What Is a Good A1C Range?
Along with fasting plasma glucose levels, 2-hour plasma glucose values, and the oral glucose tolerance test, the A1C test can be used to diagnose diabetes.5 Individuals with normoglycemia have A1C levels below 5.7%. Individuals with levels between 5.7% and 6.4% are diagnosed with prediabetes, and individuals with levels equal to or above 6.5% are diagnosed with diabetes.
*The A1C test should be performed in a lab that is National Glycohemoglobin Standardization Program (NGSP) certified and standardized to the Diabetes Control and Complications Trial (DCCT) assay.
Glycemic targets should be individualized based on patient’s specific needs, risks, and preferences. For most nonpregnant adults with diabetes, the 2021 ADA guidelines recommend an A1C goal of <7%. Epidemiological analyses of trials on intensive treatment suggest that aiming for lower A1C levels may be beneficial especially in individuals with long life expectancy and with low risk of hypoglycemia.6,7 Less stringent goals (<8%) may be more appropriate in individuals with limited life expectancy or when the risk of treatment is deemed greater than its benefit.3
How Do I Lower My A1C Levels?
Several studies have demonstrated that a strong and continuous association exists between A1C levels and subsequent diabetes.8–12 Additionally, achieving and maintaining A1C levels of <7% early in the disease progression have shown to decrease diabetes-related microvascular complications.3 As such, achieving A1C goals is important in not only managing diabetes but also minimizing long-term comorbidities.
The ADA strongly recommends making significant lifestyle changes including eating a healthy diet and exercising for all individuals with type 2 diabetes mellitus.2,3 Weight loss is also recommended for those who are overweight or obese. In most cases, pharmacological interventions used early in the disease progression can facilitate achieving glycemic target and mitigate microvascular and cardiovascular complications. For individuals with near-target A1C levels (ie, <7.5%) and who are highly motivated, pharmacotherapy can be delayed for 3-6 months to assess the effectiveness of lifestyle modification on glycemic control.
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