Symptoms, Diagnosis and Monitoring of Diabetes
Overall, 29.1 million adults in the United States have been diagnosed with Type 2 diabetes — and more than 11 million more don’t know they have it. Diabetes can develop slowly, and symptoms are not always clear at first. This is important to know because untreated diabetes can lead to serious health problems. Learning the warning signs and getting regular checkups can help catch diabetes early and protect your health.
Symptoms of diabetes
Prediabetes usually has no symptoms. Many people feel completely fine.
Those with Type 1 or Type 2 diabetes may also have no symptoms or symptoms that are mild and easy to miss for a long time.
Others may notice warning signs, such as:
- Feeling very thirsty
- Urinating more often, especially at night
- Unexplained weight loss
- Feeling hungrier than usual
- Blurry vision
- Tiredness
- Numbness or tingling in the hands or feet
- Cuts or sores that heal slowly
- Frequent infections
- Dry skin
When blood sugar becomes extremely high, more serious symptoms may appear:
- Nausea or vomiting
- Stomach pain
- Fruity-smelling breath
- Confusion or trouble thinking clearly
- Feeling disoriented or very sleepy
- Drowsiness
- Loss of consciousness (coma)
- Seizures
If you or someone you care for has these symptoms, seek medical care right away for checkup and proper diagnosis.
Who should be tested for prediabetes and diabetes?
Testing is recommended if you:
- Are 45 years or older
- Are overweight
- Are a Black American, Asian American, Latino/Hispanic American, Native American or Pacific Islander
- Had diabetes during pregnancy () or gave birth to a baby weighing more than nine pounds
- Have a family history of diabetes
- Are not physically active
- Have certain health conditions, such as:
- High blood pressure
- High cholesterol
- Fatty liver disease
- Heart disease
- HIV
- Polycystic ovary syndrome (PCOS)
If your blood sugar levels are normal, testing is recommended every three years. If you have prediabetes, testing for diabetes is often recommended every one to two years.
Tests for diagnosing prediabetes and diabetes
Three main tests can help healthcare professionals diagnose prediabetes and diabetes:
HbA1C (A1C or glycosylated hemoglobin test)
This test shows your average blood sugar over the past 2-3 months. You do not need to fast. An A1c of 5.7% to 6.4% means that you have prediabetes, and you’re at high risk for developing diabetes. Diabetes is diagnosed when A1c is 6.5% or higher.
Fasting Plasma Glucose Test (FPG)
This test measures the amount of glucose (sugar) in your blood. A fasting plasma glucose test requires having nothing to eat or drink except water for eight hours before the test. You will have your blood drawn for this test.
Oral Glucose Tolerance Test
This test shows how well your body handles sugar. To do this test, you will have nothing to eat or drink, except water, for at least eight hours. Your healthcare professional will draw blood, and then you will drink a glucose beverage. Blood is drawn again 30 and 60 minutes later. The test may take three hours. Then, your healthcare professional will compare the before-and-after glucose levels contained in your plasma to see how well your body processes the sugar.
This chart contains the FPG test’s blood glucose ranges for prediabetes and diabetes, and describes what each diagnosis means:
| Blood Glucose Range | Diagnosis | What It Means |
| Less than 100 mg/dL | Normal | Blood sugar levels are in the normal range. |
| 100 to 125 mg/dL | Prediabetes (also called impaired fasting glucose) | Blood sugar levels are higher than normal, but not high enough to be diagnosed as diabetes. This condition increases risk for developing Type 2 diabetes, heart disease and stroke. |
| 126 mg/dL or higher | Diabetes | Diabetes develops when your body doesn’t make enough insulin or becomes insulin resistant and can't efficiently use the insulin it makes. It greatly increases your risk of heart disease and stroke. |
| Blood Glucose Range | Diagnosis | What It Means |
| Less than 140 mg/dL | Normal | Blood sugar levels are in the normal range. |
| 140 to 199 mg/dL | Prediabetes | Blood sugar levels are higher than normal, but not high enough to be diagnosed as diabetes. This condition increases risk for developing Type 2 diabetes, heart disease and stroke. |
| 200 mg/dL or higher | Diabetes (Type 2 diabetes) | Type 2 diabetes develops when your body doesn’t make enough insulin or becomes insulin resistant and can’t efficiently use the insulin it makes. It greatly increases your risk of heart disease and stroke. |
Tests for Monitoring Diabetes
If you’re diagnosed with diabetes, regular monitoring helps you and your healthcare team see how well your treatment plan is working.
HbA1C
Your healthcare team will typically test your A1c at least twice a year, or more often if treatment changes are needed.
Home monitoring
Many people use home glucose monitors or continuous glucose monitors (CGMs) to track blood sugar between visits. Your healthcare professional can help you decide which option is right for you.
If you’re managing diabetes with the help of a home monitor, talk to your healthcare professional about what to do if your readings are too high or too low.
Tests to measure heart health
People living with diabetes have a higher risk of heart disease and stroke. Your healthcare team may order extra tests to monitor heart health and lower risks early.
Learn more about tests that may be used to check your heart health.
