Quick answer
What Is Diabetes Screening?
Diabetes screening is a blood test to find type 2 diabetes or prediabetes in people without symptoms. The tests used are fasting blood sugar, HbA1c, or the oral glucose tolerance test. Screening is recommended for all adults from age 35, and earlier for those who are overweight and have other risk factors.
Sources01 / Understanding the procedure
About Diabetes Screening
What Is Diabetes Screening
Type 2 diabetes develops slowly and often causes no symptoms for years. Diabetes screening is a check in people without symptoms to find type 2 diabetes or prediabetes, a blood sugar level that is already above normal but has not yet reached the diabetes threshold. When found early, lifestyle changes and treatment can prevent or delay diabetes and its complications in the heart, blood vessels, kidneys, eyes, and nerves.
How It Works in Brief
Screening begins with an assessment of risk factors, such as age, weight, waist circumference, blood pressure, and family history. After that, your blood is tested to measure the sugar level. The results are compared with the limits for normal, prediabetes, and diabetes. A high result is usually confirmed with a repeat test before a diagnosis is made.
Tests Used
- Fasting blood sugar: taken after fasting for at least 8 hours. This is covered on the Blood Sugar Test page.
- HbA1c: reflects your average blood sugar over the past 2 to 3 months and does not require fasting. This is covered on the HbA1c Test page.
- Oral glucose tolerance test (OGTT): blood sugar is checked before and 2 hours after drinking a sugar solution. This test is more sensitive for finding prediabetes and diabetes. This is covered on the Blood Sugar Test page.
Reading the Results
- Normal: fasting blood sugar below 100 mg/dL, HbA1c below 5.7 percent, or 2-hour OGTT blood sugar below 140 mg/dL.
- Prediabetes: fasting blood sugar 100 to 125 mg/dL, HbA1c 5.7 to 6.4 percent, or 2-hour OGTT blood sugar 140 to 199 mg/dL.
- May indicate diabetes: fasting blood sugar 126 mg/dL or higher, HbA1c 6.5 percent or higher, or 2-hour OGTT blood sugar 200 mg/dL or higher.
Who Should Be Screened
Guidelines recommend screening for all adults from age 35. Screening is done earlier if you are overweight, meaning a body mass index of 23 or higher based on the cutoff for Asian people, along with other risk factors such as diabetes in a parent or sibling, hypertension, abnormal cholesterol, heart disease, physical inactivity, polycystic ovary syndrome, or a history of diabetes during pregnancy. If the result is normal, screening is repeated at least every 3 years. If you have prediabetes, testing is repeated every year.
Diabetes and Heart Health
Heart and blood vessel disease is the main cause of death in people with diabetes. Diabetes is also often undiagnosed in patients who come with heart symptoms. For this reason, cardiology guidelines recommend checking fasting blood sugar or HbA1c in all patients with heart and blood vessel disease. If diabetes is found, your doctor can choose medicines that also protect the heart and kidneys.
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.
- Age 35 and OlderScreening is recommended for all adults from this age.
- OverweightA body mass index of 23 or higher, especially with a large waist circumference.
- Diabetes in a Parent or SiblingThe risk of diabetes is higher in close relatives of people with diabetes.
- Hypertension, Abnormal Cholesterol, or Heart DiseaseThese conditions often occur together with diabetes and add to heart risk.
- History of Diabetes During Pregnancy or Polycystic Ovary SyndromeIncreases the risk of type 2 diabetes later in life.
- Previously Diagnosed with PrediabetesRetesting every year is recommended.
Situations to Consider First
- Symptoms of High Blood Sugar Already PresentFrequent thirst, frequent urination, or unexplained weight loss require diagnostic testing, not screening.
- Currently Seriously Ill or Recently Had SurgeryBlood sugar may rise temporarily, so screening waits until your condition is stable.
- Conditions That Affect HbA1c ResultsSuch as anemia, recent bleeding or transfusion, pregnancy, or hemoglobin disorders. Your doctor chooses a blood sugar test.
- Already Diagnosed with DiabetesFurther blood sugar tests are for monitoring treatment, not screening.
- Not Fasting as InstructedFasting blood sugar cannot be assessed, but HbA1c can still be checked.
03 / Before the procedure
How Should You Prepare?
Preparation depends on the test chosen. The staff will tell you if you need to fast.
Fasting. For fasting blood sugar and the OGTT, do not eat or drink anything except plain water for 8 to 12 hours, usually from the night before. HbA1c does not require fasting.
Eat as usual. In the few days before the test, do not drastically cut back on rice or sweet foods, so the results reflect your everyday condition.
Medicines. Keep taking your regular medicines with a little plain water, unless your doctor gives other instructions. Bring a list of your medicines, especially corticosteroids.
Important information. Tell the staff if you are pregnant, currently ill, have recently received a blood transfusion, or have ever been diagnosed with anemia.
Unsure about the preparation instructions? Ask our team before the procedure.
04 / During the procedure
How Is the Procedure Done?
The interview, body measurements, and blood draw usually take about 30 minutes. If your doctor requests an OGTT, set aside about 2 to 3 hours.
Risk Factor Interview
A doctor or nurse asks about your medical history, the medicines you take, your pregnancy history, and diabetes in your family.
Body Measurements
Your weight, height, waist circumference, and blood pressure are measured to assess risk factors.
Blood Draw
Blood is drawn from a vein in the crease of your elbow to check fasting blood sugar, HbA1c, or both. For the OGTT, you drink a sugar solution, then blood is drawn again 2 hours later.
Reading the Results
Laboratory results are usually available on the same day. Your doctor explains what the results mean, whether a repeat test is needed, and the next steps.
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
- Finding Diabetes EarlyType 2 diabetes often causes no symptoms for years.
- Recognizing PrediabetesA stage when lifestyle changes can prevent or delay diabetes.
- Protecting the Heart and Blood VesselsControlling blood sugar from the start helps prevent complications.
- Just a Blood TestThe test is simple, and results are usually available on the same day.
- A More Complete Picture of RiskResults are read together with blood pressure, weight, and cholesterol.
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.
- Dizziness After FastingTell the staff so you can lie down, then eat soon after your blood is drawn.
- Results Need ConfirmationA single high result is not enough for a diagnosis, so a repeat test is usually needed.
- Results Affected by Temporary ConditionsIllness, stress, certain medicines, or anemia can change the results.
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 eat and return to your activities right away.
If the result is normal. Screening is repeated at least every 3 years, or more often if your risk factors increase.
If you have prediabetes. Losing about 7 percent of your body weight, being physically active for at least 150 minutes per week, and managing your diet have been shown to lower the risk of developing diabetes. Testing is repeated every year.
If the result suggests diabetes. Your doctor confirms it with a repeat test, then assesses other heart risk factors such as cholesterol, blood pressure, and kidney function, and works out a treatment plan with you.
Warning signs to watch for. Go to the emergency room right away if you experience:
- Extreme thirst, frequent urination, weakness, nausea, or vomiting
- Fast, deep breathing, or breath that smells fruity
- Confusion or reduced consciousness
- Chest pain, shortness of breath, or cold sweats
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 diabetes screening. Your doctor will explain what the results mean for your condition.
What is prediabetes?
Prediabetes is a condition in which blood sugar is already above normal but has not yet reached the diabetes threshold, for example an HbA1c of 5.7 to 6.4 percent or a fasting blood sugar of 100 to 125 mg/dL. Prediabetes usually causes no symptoms, but it increases the risk of diabetes and heart disease. Losing weight and regular physical activity can prevent or delay diabetes.
Which test is used for diabetes screening?
Fasting blood sugar and HbA1c are often used because they are simple. HbA1c does not require fasting, but it is less accurate in anemia, pregnancy, or hemoglobin disorders. The OGTT is more sensitive and can find diabetes that does not show up on fasting blood sugar, but it takes about 2 hours. Your doctor chooses the test that suits your situation.
How often should diabetes screening be repeated?
If the result is normal, screening is repeated at least every 3 years, or more often if you gain weight or develop new risk factors. People with prediabetes are advised to be tested every year. Women who have had diabetes during pregnancy are advised to be tested at least every 3 years for life, because their risk remains higher.
I feel healthy, so do I still need to be screened?
Yes, if you are 35 or older or have risk factors. Type 2 diabetes can last for years without symptoms, while high blood sugar silently damages the blood vessels. Many people only find out they have diabetes after developing complications, such as a heart attack or kidney problems.
Why does a heart hospital do diabetes screening?
Diabetes is one of the main risk factors for coronary artery disease, stroke, heart failure, and peripheral artery disease. Heart and blood vessel disease is also the main cause of death in people with diabetes. Recognizing diabetes early helps your doctor control all of your heart risk factors at the same time.
What happens if the screening result shows diabetes?
Your doctor usually confirms it with a repeat test on another day, unless you have clear symptoms and a clearly high blood sugar level. After diagnosis, your doctor assesses other risk factors such as cholesterol, blood pressure, and kidney function, then works out a treatment plan with you. Diet and physical activity remain the foundation of treatment.
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. 3. Prevention or Delay of Diabetes and Associated Comorbidities: Standards of Care in Diabetes, 2026. Diabetes Care. 2026;49(Suppl 1):S50-S60.
- US Preventive Services Task Force, Davidson KW, Barry MJ, et al. Screening for prediabetes and type 2 diabetes: US Preventive Services Task Force recommendation statement. JAMA. 2021;326(8):736-743.
- 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.
- Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403.