Diabetes is a condition that affects the body’s ability to either produce or use insulin. Insulin helps the body utilize blood sugar for energy. Diabetes results in blood sugar that rises to abnormally high levels.
The symptoms of diabetes often appear suddenly or may sometimes occur gradually and are often the reason for testing the blood sugar levels. Over time, diabetes results in damage to blood vessels and nerves, causing a variety of symptoms, including:
- Difficulty seeing
- Tingling and numbness in the hands and feet
- Increased risk for a heart attack or stroke
An early diagnosis means you can start treatment and take steps toward a healthier lifestyle.
Who should be undergoing a Diabetes test?
Anyone who has symptoms of diabetes should be tested for the disease. Some people will not have any symptoms but may have risk factors for diabetes and need to be tested. Testing allows health care professionals to find diabetes sooner and work with their patients to manage diabetes and prevent complications.
Some people should be tested for diabetes even if they aren’t experiencing symptoms. The American Diabetes Association (ADA) recommends that you undergo diabetes testing if you’re overweight (body mass index greater than 25) and fall into any of the following categories:
- You’re a high-risk ethnicity (African-American, Latino, Native American, Pacific Islander, Asian-American, among others).
- You have high blood pressure, high triglycerides, low HDL cholesterol, or heart disease.
- You have a family history of diabetes.
- You have a personal history of abnormal blood sugar levels or signs of insulin resistance.
- You don’t engage in regular physical activity.
- You’re a woman with a history of polycystic ovary syndrome (PCOS) or gestational diabetes.
The ADA also recommends you undergo an initial blood sugar test if you’re over the age of 45. This helps you establish a baseline for blood sugar levels. Because your risk for diabetes increases with age, testing can help you identify your chances of developing it.
Diabetes Blood Test
Test for type 1 diabetes and type 2 diabetes
Glycated hemoglobin (A1C) test.
This blood test, which doesn’t require fasting, indicates your average blood sugar level for the past two to three months. It measures the percentage of blood sugar attached to hemoglobin, the oxygen-carrying protein in red blood cells.
The higher your blood sugar levels, the more hemoglobin you’ll have with sugar attached. An A1C level of 6.5 percent or higher on two separate tests indicates that you have diabetes. An A1C between 5.7 and 6.4 percent indicates prediabetes. Below 5.7 is considered normal.
If the A1C test results aren’t consistent, the test isn’t available, or you have certain conditions that can make the A1C test inaccurate — such as if you’re pregnant or have an uncommon form of hemoglobin (known as a hemoglobin variant) — your doctor may use the following tests to diagnose diabetes:
Random blood sugar test
A blood sample will be taken at random times. Regardless of when you last ate, a random blood sugar level of 200 milligrams per deciliter (mg/dL) — 11.1 millimoles per liter (mmol/L) — or higher suggests diabetes.
Fasting blood sugar test
A blood sample will be taken after an overnight fast. A fasting blood sugar level less than 100 mg/dL (5.6 mmol/L) is normal. A fasting blood sugar level from 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is considered prediabetes. If it’s 126 mg/dL (7 mmol/L) or higher on two separate tests, you have diabetes.
Oral glucose tolerance test
For this test, you fast overnight, and the fasting blood sugar level is measured. Then you drink a sugary liquid, and blood sugar levels are tested periodically for the next two hours.
A blood sugar level of less than 140 mg/dL (7.8 mmol/L) is normal. A reading of more than 200 mg/dL (11.1 mmol/L) after two hours indicates diabetes. A reading between 140 and 199 mg/dL (7.8 mmol/L and 11.0 mmol/L) indicates prediabetes.
If type 1 diabetes is suspected, your urine will be tested to look for the presence of a byproduct produced when muscle and fat tissue are used for energy because the body doesn’t have enough insulin to use the available glucose (ketones). Your doctor will also likely run a test to see if you have the destructive immune system cells associated with type 1 diabetes called autoantibodies.
Test for Gestational diabetes
Gestational diabetes can occur when a woman is pregnant. The ADA suggests that women with risk factors should be tested for diabetes at their first visit to see if they already have diabetes. Gestational diabetes happens in the second and third trimester.
Doctors may use two types of tests to diagnose gestational diabetes:
Initial glucose challenge test
This test involves drinking a glucose syrup solution. Blood is drawn after an hour to measure blood sugar levels. A result of 130 to 140 mg/dL or less is considered normal. A higher-than-usual reading indicates the need for further testing.
If the blood sugar level is higher than normal, it only means you have a higher risk of gestational diabetes. The doctor will order a follow-up test to determine if you have gestational diabetes.
Follow-up glucose tolerance testing
This test involves not eating anything overnight. You’ll be asked to fast overnight and then have your fasting blood sugar level measured. Then you’ll drink another sweet solution (this one containing a higher concentration of glucose) and your blood sugar level will be checked every hour for a period of three hours.
If at least two of the blood sugar readings are higher than the normal values established for each of the three hours of the test, you’ll be diagnosed with gestational diabetes.
Diabetes Urine Test
Urine tests aren’t always used to diagnose diabetes. Doctors often use them if they think you may have type 1 diabetes. The body produces ketone bodies when fat tissue is used for energy instead of blood sugar.
Laboratories can test urine for these ketone bodies. If ketone bodies are present in moderate to large amounts in the urine, this could indicate your body is not making enough insulin.
The ketone test is generally recommended for people with type 1 diabetes. Those with type 1 diabetes should test their urine for ketones when they are ill, especially if they have vomiting and nausea.
Pregnant women with type 1 diabetes may also be advised to test their urine for ketones. Ketone testing is also done when the blood sugar is noted to be very high.
Frequently Asked Questions about Diabetes test
Can diabetes be detected in a blood test?
Health care providers can diagnose diabetes, through blood tests. The blood tests show if the blood glucose, also called blood sugar, is too high.
What is the normal range for blood sugar?
Normal blood sugar levels are less than 100 mg/dL after not eating (fasting) for at least eight hours. And they’re less than 140 mg/dL two hours after eating. During the day, levels tend to be at their lowest just before meals.
When should you have a blood test for diabetes?
Your doctor may recommend blood sugar testing four to 10 times a day if you have type 1 diabetes. You may need to test before meals and snacks, before and after exercise, before bed, and sometimes during the night.
Can diabetes be detected in a urine test?
Urine tests aren’t ever used to diagnose diabetes. However, they may be used to monitor a person’s levels of urine ketones and urine glucose. Sometimes they’re used to ensure diabetes is being managed properly.
What should not be found in urine?
Sugar (glucose, not usually found in urine) Nitrite (not usually found in urine) Ketone (a metabolic product, not usually found in urine) Bilirubin (a breakdown product of hemoglobin, not usually found in urine)
What is a positive urine test?
If your urine test is positive, it means your kidneys can no longer filter your blood as well as they should. It also shows you have blood vessel disease that could lead to heart problems.
Does a high a1c always mean diabetes?
If your A1C level is between 5.7 and 6.4 percent, you have prediabetes (also called impaired fasting glucose), which means you have a high risk of developing diabetes in the future. An A1C level of 6.5 percent or higher on two separate occasions shows that you have diabetes.
What does it feel like when your blood sugar is too high?
The main symptoms of hyperglycemia are increased thirst and a frequent need to urinate. Other symptoms that can occur with high blood sugar are; Headaches. Tiredness.