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How Is Diabetes Diagnosed?
Diabetes is diagnosed through a series of blood glucose tests that measure how your body manages sugar. These tests help determine whether you have normal blood sugar levels, prediabetes, or diabetes.
What are the main tests used to diagnose diabetes?
The four most common diagnostic tests for diabetes are:
Fasting Plasma Glucose (FPG)
A1C Test (Hemoglobin A1C)
Oral Glucose Tolerance Test (OGTT)
Random Plasma Glucose Test
Each test measures blood sugar differently and may be used alone or in combination for accuracy.
What is the Fasting Plasma Glucose (FPG) test?
The FPG test measures your blood sugar after fasting for at least 8 hours.
Normal: 99 mg/dL or below
Prediabetes: 100–125 mg/dL
Diabetes: 126 mg/dL or above
It’s a quick and simple way to screen for diabetes or prediabetes.
What does the A1C test show?
The A1C test measures your average blood glucose over the past 2–3 months. It’s widely used because fasting isn’t required.
Normal: Below 5.7%
Prediabetes: 5.7%–6.4%
Diabetes: 6.5% or higher
This test has become more popular globally. For instance, screening rates in Australia more than doubled between 2015 and 2019.
What is the Oral Glucose Tolerance Test (OGTT)?
The OGTT measures blood sugar before and after drinking a glucose-rich drink. It’s especially useful for detecting gestational diabetes.
Normal (2 hours after): 139 mg/dL or below
Prediabetes: 140–199 mg/dL
Diabetes: 200 mg/dL or higher
While once widely used, OGTT testing has declined in favor of A1C testing in many regions.
What is the Random Plasma Glucose test?
This test measures your blood sugar at any time, regardless of when you last ate.
Diabetes: 200 mg/dL or higher
It’s often used when diabetes symptoms (such as excessive thirst, fatigue, or blurred vision) are already present.
Can diabetes be detected through a urine test?
Yes. A urine test can detect sugar or ketones, which may indicate uncontrolled diabetes or diabetic ketoacidosis. However, urine tests are usually supplementary and not diagnostic on their own.
How accurate are these tests?
A1C Test: Sensitivity ranges from 24%–78%, specificity from 79%–100% at the 6.5% cutoff.
FPG Test: Sensitivity ranges from 40%–94%, specificity from 83%–100% at the 126 mg/dL cutoff.
Because no single test is perfect, doctors often repeat or combine tests for confirmation.
What are the diagnostic thresholds for diabetes?
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| A1C | < 5.7% | 5.7%–6.4% | ≥ 6.5% |
| Fasting Plasma Glucose | ≤ 99 mg/dL | 100–125 mg/dL | ≥ 126 mg/dL |
| OGTT (2 hours) | ≤ 139 mg/dL | 140–199 mg/dL | ≥ 200 mg/dL |
| Random Plasma Glucose | — | — | ≥ 200 mg/dL |
How common is diabetes worldwide?
Over 830 million people were living with diabetes in 2022, up from 200 million in 1990.
Around 14% of adults worldwide now have diabetes.
More than 2 million deaths were linked to diabetes in 2021.
Early diagnosis dramatically reduces the risk of complications like blindness, kidney failure, heart attacks, and strokes.
Why is early diagnosis important?
Detecting diabetes early allows for timely management and lifestyle adjustments, which prevent or delay serious complications. Most cases are confirmed after two abnormal test results, unless symptoms are severe.
Why Choose NAMG for Diabetes Care with RPM?
At Northern Arizona Medical Group (NAMG), we combine expert diabetes management with Remote Patient Monitoring (RPM) technology. This allows our care team to track your blood sugar trends and health metrics in real-time — helping you manage your diabetes more effectively and conveniently.
How does RPM help diabetic patients at NAMG?
Our RPM services help patients:
Maintain stable blood sugar levels through continuous monitoring
Reduce the risk of complications with early intervention
Receive timely medical support from our clinical team
Lead a healthier, more balanced life with less stress
Who can benefit from RPM services?
Whether you have Type 1 or Type 2 diabetes, RPM can support your treatment plan by improving tracking, adherence, and overall outcomes.
Contact Northern Arizona Medical Group (NAMG) Today!
If you’re ready to start managing your diabetes more effectively with our RPM services, contact Northern Arizona Medical Group today!
Call us at 928-757-8440 or visit our website at namg.us to learn more about our RPM services and how we can help you take charge of your health.
