Quick answer
What Is HbA1c Test?
The HbA1c test is a blood test that reflects your average blood sugar over the past two to three months. It does not require fasting. A result of 6.5 percent or higher may indicate diabetes, while 5.7 to 6.4 percent indicates prediabetes. For people with diabetes, HbA1c is used to monitor treatment.
Sources01 / Understanding the procedure
About HbA1c Test
What Is HbA1c
Hemoglobin is a protein inside red blood cells. Sugar in the blood attaches to hemoglobin, and the higher the blood sugar level, the more sugar attaches. Because red blood cells live for about three months, HbA1c reflects your average blood sugar over the past two to three months, not just at the moment the blood is drawn.
How It Works in Brief
Blood is taken from your arm or fingertip. The laboratory measures what percentage of hemoglobin has sugar attached, and the result is then compared with diagnostic thresholds or treatment targets.
Reading the Results
- Below 5.7 percent: within the normal range.
- 5.7 to 6.4 percent: prediabetes, meaning a high risk of developing diabetes. Lifestyle changes help a great deal at this stage.
- 6.5 percent or higher: may indicate diabetes. The result is usually confirmed with a repeat test, unless symptoms and blood sugar levels are already clearly high.
For many people with diabetes, the HbA1c target is below 7 percent. The target may differ for older adults or people who are prone to low blood sugar, and is set together with your doctor.
HbA1c and Heart Health
Diabetes increases the risk of coronary artery disease, stroke, and heart failure, often without symptoms at the start. For this reason, cardiology guidelines recommend checking for diabetes, with fasting blood sugar or HbA1c, in all patients with heart and blood vessel disease.
When Results May Be Inaccurate
HbA1c can be misleading in anemia, recent bleeding or blood transfusion, pregnancy, severe kidney disease, and inherited hemoglobin disorders such as thalassemia and certain hemoglobin variants that are fairly common in Southeast Asia. In these situations, the doctor uses other blood sugar tests as a complement.
02 / Understanding the procedure
When Is This Procedure Considered?
A doctor may consider this procedure in the situations below. The decision is always made after a thorough assessment.
- Heart and Blood Vessel DiseaseAll patients with cardiovascular disease are advised to be checked for diabetes, which often goes undiagnosed.
- Diabetes Risk FactorsFor example excess weight, high blood pressure, high cholesterol, or a family history of diabetes.
- Symptoms of High Blood SugarSuch as frequent thirst, frequent urination, tiring easily, or unexplained weight loss.
- Monitoring People with DiabetesTo assess whether treatment has reached its target and when it needs to be adjusted.
- Periodic Health Check-UpsAs part of a medical check-up to detect prediabetes earlier.
Situations to Consider First
- Anemia or Recent BleedingChanges in the lifespan of red blood cells make HbA1c results less accurate.
- Recent Blood TransfusionDonor blood is also measured, so the doctor uses other blood sugar tests for the time being.
- Inherited Hemoglobin DisordersThalassemia or certain hemoglobin variants can affect the results with some testing methods.
- PregnancyBlood changes during pregnancy make HbA1c less accurate for diagnosing gestational diabetes.
- Severe Kidney Disease or DialysisResults may not reflect actual blood sugar well, so they are interpreted together with other tests.
03 / Before the procedure
How Should You Prepare?
The HbA1c test uses a blood sample and usually does not require any special preparation.
No fasting needed. HbA1c is not affected by what you eat that day, so it can be tested at any time. If it is done together with a fasting blood sugar or cholesterol test, follow the fasting instructions for those tests.
Medications. Take your medications as usual, including diabetes medications, unless your doctor gives other instructions.
Important information. Tell the staff if you are pregnant, have recently received a blood transfusion, have had bleeding, have anemia or thalassemia, or are on dialysis.
Previous results. Bring your previous HbA1c results and blood sugar records so the doctor can see how they have changed.
Clothing. Wear a top with loose sleeves so your arm is easy to prepare.
Unsure about the preparation instructions? Ask our team before the procedure.
04 / During the procedure
How Is the Procedure Done?
Blood collection is usually finished within 10 minutes, and HbA1c results are usually available on the same day.
Identity Check
The staff match your identity with the test request and ask about conditions that may affect the results.
Blood Collection
Blood is drawn from a vein in the crook of your elbow into a purple-top tube. For some rapid tests, a single drop of blood from your fingertip is enough.
Laboratory Analysis
The equipment measures the percentage of hemoglobin that has sugar attached. The result is reported as a percentage, sometimes also in mmol/mol.
Interpreting the Results
The doctor interprets the results together with your blood sugar, symptoms, and medications, then decides whether a repeat test, lifestyle changes, or treatment adjustments are needed.
05 / Benefits and risks
Benefits and Risks Should Be Discussed Together.
Every medical procedure has benefits and risks. Your doctor will explain both for your situation before the procedure.
Benefits You Can Expect
- No FastingCan be tested at any time because it is not affected by what you eat that day.
- A Three-Month PictureShows your long-term average blood sugar, not just a single moment.
- Earlier Detection of PrediabetesGives you the chance to prevent diabetes through lifestyle changes.
- Assesses Treatment SuccessHelps the doctor adjust diabetes medications appropriately.
- Protects the HeartDiabetes that is detected and controlled lowers the risk of heart and blood vessel complications.
The benefits of a procedure are not a promise of a cure. Ask how the results will affect your care plan.
Risks You Should Know
- Minor Pain or BruisingAt the needle site, usually mild and quick to go away.
- Brief Dizziness or FaintingSome people feel dizzy when blood is drawn. Tell the staff so you can lie down.
- Less Accurate Results in Certain ConditionsAnemia, transfusion, pregnancy, or hemoglobin disorders can make the results misleading, so the doctor uses other tests.
- Does Not Capture Daily Ups and DownsHbA1c is an average, so blood sugar that is often very high or very low needs to be monitored in other ways.
- Infection at the Puncture SiteVery rare because the skin is cleaned and the equipment used is sterile and single-use.
Risks can differ from person to person. A full explanation and consent are given after an individual assessment.
06 / After the procedure
What Is Recovery Like?
There is no recovery period. You can return to your activities right away.
Puncture site. A small bruise is normal and goes away within a few days.
Discussing the results. Discuss the results with your doctor, including the HbA1c target that suits you.
If the result is high. A balanced diet, regular physical activity, and losing weight if you are overweight help lower HbA1c. People with diabetes may need their medications adjusted.
Next test schedule. For people with diabetes, HbA1c is usually checked every three months if treatment has been changed or has not reached its target, and at least twice a year once it is stable.
Warning signs. Go to the emergency room right away or contact the medical team if you experience:
- Extreme thirst, frequent urination, weakness, and nausea or vomiting
- Shaking, cold sweats, or confusion, especially while taking diabetes medications
- Chest pain, shortness of breath, or cold sweats
- A drooping face, arm weakness, or slurred speech
Know the Signs That Need Prompt Care.
Follow the team's guidance on warning signs. If severe or sudden symptoms appear after the procedure, go to the nearest emergency department right away or call Heart Attack Center 1500 258.
07 / Team and support
Doctors and Procedure Support
The doctors below are listed for this procedure. Listed by name, not by ranking.
dr. Debby C. Soemitha, Sp.PD
Internal Medicine
Clinical focusDiabetes and Diabetes Complications · Obesity and Metabolic Disease
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Dr. med. dr. Denio A. Ridjab, Sp.JP(K)
Interventional Cardiology
Coronary Intervention Procedures +2 centers
Clinical focusInterventional Cardiology · Coronary Artery Disease
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dr. Juweni Joe, Sp.GK
Clinical Nutrition
Clinical focusMedical Nutrition Intervention · Nutrition for Cardiovascular Patients
View Profile08 / Common questions
Before You Plan the Procedure.
Frequently asked questions about the HbA1c test. Your specific targets and testing schedule are determined by your doctor.
Do I need to fast before an HbA1c test?
No. HbA1c reflects your average blood sugar over two to three months, so it is not affected by what you eat that day. You can eat, drink, and take your medications as usual. If HbA1c is checked together with fasting blood sugar or cholesterol, follow the fasting instructions for those tests.
What is the difference between HbA1c and a regular blood sugar test?
A regular blood sugar test measures the sugar level at the moment the blood is drawn, so it is affected by food and activity that day. HbA1c reflects your average blood sugar over two to three months. The two complement each other, and doctors often use both to diagnose and monitor diabetes.
What is the HbA1c target for people with diabetes?
For many adults with diabetes, the target is below 7 percent. The target may be less strict for older adults, people with many other health conditions, or those who often have low blood sugar. Your doctor determines the target that suits your situation.
How often does HbA1c need to be checked?
For people with diabetes who have reached their target, HbA1c is usually checked at least twice a year. If treatment has recently been changed or has not reached its target, it is usually checked every three months. For people without diabetes who have risk factors, the doctor sets a regular testing schedule based on previous results.
Why does a cardiologist check HbA1c?
Diabetes is one of the main risk factors for coronary artery disease, stroke, and heart failure, and it often goes unnoticed. Cardiology guidelines recommend checking for diabetes in all patients with heart disease. The results help the doctor choose medications that also protect the heart and set treatment targets.
Can HbA1c results be wrong?
Yes, in certain situations. Anemia, recent bleeding or blood transfusion, pregnancy, severe kidney disease, and hemoglobin disorders such as thalassemia can mean the results do not reflect your actual blood sugar. Tell your doctor if you have any of these conditions, so the results are interpreted together with other tests.
Sources and Medical Review
Translated from the Indonesian edition medically reviewed by dr. Debby C. Soemitha, Sp.PD.
Sources as cited in the Indonesian edition.
- American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes, 2026. Diabetes Care. 2026;49(Suppl 1):S27-S49.
- American Diabetes Association Professional Practice Committee for Diabetes. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes, 2026. Diabetes Care. 2026;49(Suppl 1):S132-S149.
- Marx N, Federici M, Schütt K, et al. 2023 ESC Guidelines for the management of cardiovascular disease in patients with diabetes. Eur Heart J. 2023;44(39):4043-4140.
- Little RR, Roberts WL. A Review of Variant Hemoglobins Interfering with Hemoglobin A1c Measurement. J Diabetes Sci Technol. 2009;3(3):446-451.