Symptoms, Diagnosis and Monitoring of Diabetes

doctor meeting with patient

About 8 million American adults have Type 2 diabetes — and many don’t know it. And Type 1 diabetes often remains undiagnosed until symptoms become so severe that hospitalization is required.

Both of these facts speak to a larger truth: Left untreated, diabetes can cause numerous health complications. That’s why it’s crucial to know the warning signs and to see a healthcare provider regularly for routine wellness screenings.

Symptoms

Prediabetes has no symptoms.

Similarly, those with Type 1 or Type 2 diabetes may have no symptoms — or such mild symptoms that they go unnoticed for quite some time.

Still, since some people experience warning signs, it’s worth familiarizing yourself with the symptoms below:

Prediabetes Type 1 Diabetes Type 2 Diabetes
No symptoms Increased or extreme thirst Increased thirst
  Increased appetite Increased appetite
  Increased fatigue Fatigue
  Increased or frequent urination Increased urination, especially at night
  Unusual weight loss Weight loss
  Blurred vision Blurred vision
  Fruity odor or breath Sores that do not heal
  In some cases, no symptoms In some cases, no symptoms

If you have any of these symptoms, see your health care provider right away. Diabetes can only be diagnosed by your healthcare provider.

Who should be tested for prediabetes and diabetes?

The U.S. Department of Health and Human Services recommends that you should be tested if you are:

  • Overweight and older than 45 years
  • Overweight, younger than 45 and have one or more additional risk factors, such as:
    • High blood pressure
    • High cholesterol
    • A family history of diabetes
    • African-American, Asian-American, Latino/Hispanic-American, Native American or of Pacific Islander descent
    • A history of gestational diabetes (diabetes during pregnancy) or delivering a baby more than 9 pounds

If your blood glucose levels are normal, you should be tested about every three years. If you have prediabetes, you should be checked for diabetes every one to two years after that diagnosis.

Tests for Diagnosing Prediabetes and Diabetes

Three types of tests can help healthcare providers make a diagnosis of prediabetes and diabetes:

HbA1C (A1C or glycosylated hemoglobin test)

The A1C test can diagnose prediabetes and diabetes. It measures your average blood glucose control for the past two to three months. This test is more convenient because no fasting is required. An A1C of 5.7 percent to 6.4 percent means that you have prediabetes, and you’re at high risk for the development of diabetes. Diabetes is diagnosed when the A1C is 6.5 percent or higher.

Fasting Plasma Glucose Test (FPG)

A fasting plasma glucose test requires fasting (nothing to eat or drink except water) for eight hours before the test.

For this test, the healthcare provider draws blood from the patient. Then the plasma (the fluid part of the blood) is combined with other substances to determine the amount of glucose in the plasma, as measured in mg/dL.

The chart below 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
100 to 125 mg/dL Prediabetes (also called Impaired Fasting Glucose) Blood glucose 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 more Diabetes mellitus (type 2 diabetes) Type 2 diabetes develops when your body doesn’t make enough insulin or develops “insulin resistance” and can't efficiently use the insulin it makes. It greatly increases your risk of heart disease and stroke.

Oral Glucose Tolerance Test (OGTT)

This test measures how well the body handles a standard amount of glucose.

To conduct this test, your healthcare provider will draw blood before and two hours after you drink a large, premeasured beverage containing glucose. Then, your doctor can compare the before-and-after glucose levels contained in your plasma to see how well your body processed the sugar. These levels are measured in mg/dL.

The chart below contains the oral glucose tolerance test (OGTT) ranges for prediabetes and diabetes, as well as what each diagnosis means:

Blood Glucose Range Diagnosis What It Means
140 to 199 mg/dL Prediabetes (also called Impaired Fasting Glucose) Blood glucose 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 mellitus (type 2 diabetes) Type 2 diabetes develops when your body doesn’t make enough insulin or develops “insulin resistance” 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 Type 2 diabetes, you can monitor your blood sugar level several ways to evaluate how well your treatment plan is working:

HbA1C (A1C or glycosylated hemoglobin test)

Your healthcare provider may regularly perform a test called HbA1c (A1C, or glycosylated hemoglobin test).

An A1C test provides a picture of your average blood sugar control for the past two to three months. Blood sugar is measured by the amount of glycosylated hemoglobin (A1C) in your blood.

Home monitoring

Easy-to-use home monitors allow patients to test their blood sugar on their own. A variety of these devices are on the market.

If you’re managing diabetes with the help of a home monitor, be sure to consult with your doctor to learn what to do when your results are too high or low for you.

Tests to Measure Heart Health

People with diabetes are at increased risk for a range of health complications, including cardiovascular disease.

Learn more about non-invasive and invasive tests doctors may use to check heart health.


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