4 Top Tests for Diabetes: Everything You Want to Know

Diabetes is among the most common metabolic disorders. According to the IDF Diabetes Atlas, 2021, 10.5% of the adult population globally are suffering from diabetes. Even more concerning is the fact that 57% of the patients remain undiagnosed! That's why it's important to understand diabetes tests whether or not you exhibit symptoms.  

The doctor uses a set of blood tests to diagnose whether the patient is diabetic, prediabetic, or has gestational diabetes. These blood tests show the levels of blood glucose whether they are higher than normal. Some of these tests are the fasting blood sugar (FBS) test, A1C test, Oral glucose tolerance test (OGTT), and Random blood sugar (RBS) test. 

Patients are advised not to attempt self-diagnosis with at-home kits as they are not completely reliable and may provide erroneous results. 

Given the statistics that India has 101 million people with diabetes, learning about the 4 top tests for diabetes is important for accurate diagnosis of the condition.

Blood Sugar Levels

Your body's primary energy source is blood glucose, also known as blood sugar. Your body converts the carbs you eat or drink into glucose. If you haven't eaten in a while, your body uses the glucose stored in your liver and muscle to maintain normal blood sugar levels. Additionally, consuming sugary or carbohydrate-rich foods and beverages raises your blood glucose levels. 

Insulin is an essential hormone or chemical messenger that helps maintain blood sugar levels within a healthy range. Problems with your body's insulin production or use can lead to poor blood glucose control or diabetes. 

Blood Sugar Reference Range and Interpretation 

Knowing different blood sugar level ranges helps identify conditions like diabetes or symptoms of prediabetes at the early stages. 

• Normal Blood Sugar Levels: 

A blood sugar level of 99 milligrams per deciliter (mg/dL) or less is considered normal during fasting. An appropriate fasting blood glucose range for people with controlled diabetes is 80–130 mg/dL. Less than 180 mg/dL is considered normal 1-2 hours after a meal.

• High Blood Sugar Levels: 

High blood sugar levels indicate excess glucose in the blood. This occurs when the body does not produce enough insulin or cannot use it properly. A blood glucose level of 100–125 mg/dL during fasting is considered abnormal and typically signifies prediabetes. A diabetes diagnosis is considered positive if your fasting blood glucose level is more than 125 mg/dL on two different tests.

Frequent urination, excessive hunger or thirst, and weight changes are possible symptoms of diabetes.

4 Top Tests For Diabetes

Doctors can use various diagnostic tests, including the 4 top tests for diabetes, to measure your blood glucose levels. While some tests are conducted on an empty stomach, others don't require any meal-related considerations.

1. A1C Test

The A1C test determines your normal blood sugar levels over the previous three months. It is the most popular blood test used to diagnose Type 1 and Type 2 diabetes and track a diabetic patient’s blood sugar levels. You are not required to fast for the A1C test. 

A medical professional draws your blood from a vein. Then, blood samples are taken for an A1C test, and results are typically available 4 to 24 hours later.

Results Interpretation: The normal range is below 5.7%. Prediabetes is defined as 5.7%–6.4%, and diabetes as 6.5% and above.

2. Random Blood Sugar Test

There is no set time of day for random blood sugar tests, and fasting is not required. A blood sample is taken, and the results are usually given on the same day. A random blood sugar testing is carried out as an outpatient treatment. It's a quick, safe, and non-invasive test. An RBS test can diagnose diabetes as well as prediabetes.

Results Interpretation: Diabetes is suggested when the blood sugar level is 200 mg/dL or higher, particularly if it is accompanied by any of the following signs of elevated blood sugar:

• Increased urination
• Increased thirst
• Weight loss
• Blurry vision

3. Fasting Blood Sugar (FBS) Test

For the FBS test, you'll need to fast for at least 8 hours to prevent false readings that may affect the results as food consumption can temporarily spike blood sugar levels. If accessible, the easiest option is to fast overnight and take the test in the morning. The results will be sent to you in 24 to 72 hours.

Results Interpretation: The normal range is between 70 and 100 mg/dL. Prediabetes is defined as 100–126 mg/dL, and diabetes is defined as 126 mg/dL and higher.

4. Glucose Tolerance Test

A glucose tolerance test (OGTT) measures the body's reaction to glucose. Although it's frequently used as a Type 2 diabetes screening test, a modified version is also used to check for gestational diabetes.

Similar to the fasting blood sugar test, the glucose tolerance test requires a blood sample to be taken prior to breakfast and requires fasting. This is to check your blood glucose levels after a fast.

Following that, you'll receive eight ounces of a glucose solution. Your blood sugar levels will be measured again in two hours by taking a blood sample.

Results Interpretation: The normal range is 140 mg/dL or less at two hours. Diabetes is indicated by 200 mg/dL and above, while prediabetes is indicated by 140–199 mg/dL.

5. Other Test

The Postprandial Blood Sugar (PPBS) test is a routine test used to diagnose diabetes. Blood glucose levels are measured two hours after a meal using the PPBS (Post Prandial Blood Sugar) test. This test is ideal for diabetes management and routine health checks.

‍Get Insights into Your Blood Sugar Level with Aware! 

Diagnosing diabetes involves a variety of blood glucose tests, such as hemoglobin A1c, glucose tolerance, fasting plasma glucose, and random plasma glucose testing. By taking your medication as prescribed, monitoring your blood sugar levels at home, and implementing a few other small lifestyle adjustments, you can manage your diabetes and stay well.

Aware uses personalized nudges, diet and lifestyle care plans, and intelligent glucose logging to help you stay on track and control your blood sugar. With just one app, you can easily monitor your blood sugar levels, medication intake, physical activity, and food choices. Begin changing your life right now with Aware.

 FAQ’s

1. What is the best test for diabetes?

The primary blood test for diabetes diagnosis is the HbA1c test. It is a reliable blood test for identifying type 1 and type 2 diabetes. It measures your blood sugar levels over the previous two to three months. No fasting is required for HbA1c.

2. What are the 4 tests for diabetes?

There are four top tests for diabetes: the RBS Test, the FBS Test, the A1C Test, and the OGTT Test. 

• The A1C test estimates your blood sugar average over the previous two or three months.
• Your blood sugar is measured using a fasting blood test after an overnight fast.
• A glucose tolerance test examines your blood sugar levels both before and after consuming a glucose-containing liquid.
• A random blood sugar test takes a reading of your blood sugar at that moment. 

3. Is HbA1c the best test for diabetes?

While not perfect, the HbA1c test is an important diagnostic and management tool for diabetes. A blood test called the HbA1c is used to identify type 2 diabetes, pre diabetes and track blood glucose control in diabetics. The acronym for glycated hemoglobin is HbA1c. The test is sometimes also known as hemoglobin A1c.

4. Which is more accurate, HbA1c or OGTT?

HbA1c is a more reliable and practical measure of average blood glucose over the long term. However, in certain cases, especially when it comes to prediabetes and early diabetes diagnosis where HbA1c results are unclear, OGTT may be more accurate. 

The selection of a test depends upon the patient's condition and occurs within a specific clinical setting of application.

5. What is a high fasting insulin level?

A high fasting insulin level, known as hyperinsulinemia, indicates that your body is producing too much insulin to maintain normal blood glucose levels. This often means your cells are becoming resistant to insulin's effects (insulin resistance).

The fasting insulin normal range is 2-20 μU/mL. However, the optimal level is below 8 μU/mL.

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About the Author
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Dr. Satish Madiraju, a renowned cardiologist is passionate about consumer heart health and is on a mission to prevent a million heart attacks. He shares his expertise not only on heart health but also on leadership, digital health, and improving patient experience.