Blood tests for diabetes

A blood test for diabetes measures the amount of glucose or sugar in a person’s blood. Diabetes is a condition in which the body has trouble converting sugar from food into energy. It can be caused when there isn’t enough insulin or the insulin in the body is not working well enough to process sugar. This can lead to high blood sugar levels in the bloodstream, causing symptoms like increased thirst and frequent urination, among other complications, as the disease progresses. 

Testing for different types of diabetes

High blood sugar levels could indicate one of various types of diabetes. The main types of diabetes include Type 1, Type 2, and gestational diabetes. In some cases, blood sugar levels may be higher than normal but not high enough for a diabetes diagnosis (prediabetes). 

Type 1 Diabetes

Type 1 diabetes is an autoimmune disease in which the pancreas stops producing insulin. It’s usually diagnosed in children or young adults, but it can also be diagnosed in adults who have never had symptoms before. Type 1 diabetes is typically treated with insulin injections and daily blood glucose tests.

Type 2 Diabetes

Type 2 diabetes occurs when the body doesn’t produce enough insulin, or when cells stop responding to insulin properly. Type 2 diabetes is the most common form of diabetes among adults. It tends to develop slowly over time and can often go undetected for years before being diagnosed by a doctor or healthcare provider. Type 2 diabetes can be managed through diet and exercise, although it often requires medication or insulin shots as well.

Gestational Diabetes

Gestational diabetes occurs during pregnancy and affects about 7% to 10% of all pregnant women. It can develop when the mother’s body doesn’t produce enough insulin to regulate high blood glucose levels during pregnancy, which raises the risk for complications like high blood pressure, preeclampsia, and preterm birth. Gestational diabetes usually goes away after pregnancy, but women who have had it are at a greater risk for developing Type 2 diabetes later in life.

Who should be tested for diabetes?

Diabetes is a treatable condition that can be managed, but it’s important to catch it early. Everyone should be tested at least once in their lifetime. People should get initially screened for diabetes at age 35, and, if the test results are normal, screened every three years afterward. 

There are several groups of people who are at higher risk for diabetes and should be screened, according to the American Diabetes Association (ADA). These groups of people include:

• People who are overweight or obese (BMI over 25) with other risk factors, such as abnormal cholesterol levels, high blood pressure, heart disease, or a close relative with diabetes
• Women with a history of gestational diabetes or polycystic ovarian syndrome
• People with a history of prediabetes

Anyone who has any of these risk factors should talk to their healthcare provider about getting tested for diabetes. If you’re pregnant or planning to become pregnant, it’s also important for you to get tested for diabetes. Pregnancy can put extra stress on the body and make it more difficult for the body to control the level of glucose in the blood.

Signs and symptoms of diabetes

Diabetes can cause an array of signs and symptoms. Many people don’t experience symptoms in the early stages of the disease. A doctor or healthcare professional may recommend you get screened for diabetes if you have any of the following symptoms:

• Excessive thirst
• Frequent urination (especially at night)
• Unexplained weight loss
• Extreme fatigue
• Blurry vision
• Nausea, vomiting, or stomach pain
• Slow healing of cuts or infections
• Recurrent yeast infections

If left untreated, diabetes can lead to various complications, some of which can be severe. These complications include nerve damage, eye damage, kidney disease, and heart disease. Early detection and treatment can help keep blood sugar levels under control and prevent severe complications, such as blindness and kidney failure.

What are the different blood tests for diabetes?

There are many different tests for diabetes, and they can be used in a variety of ways. They may be used to diagnose diabetes or monitor the current state of the disease. The most common blood tests for diabetes involve obtaining a blood sample and include the following:

Fasting blood glucose tests

A fasting blood glucose test is the most common type of blood test for diabetes. The fasting blood sugar test measures the amount of glucose in your blood after a period of fasting. It requires that you have not eaten for at least eight hours prior to the test, and it is usually performed in the morning before the first meal of the day. This test can be used as an initial screening tool for diabetes or as part of a follow-up evaluation after you’ve been diagnosed with diabetes.

The blood sugar ranges for a diabetes diagnosis after a fasting blood sugar test are:

• Normal: 99 mg/dL or below
• Prediabetes: 100 – 125 mg/dL
• Diabetes: 126 mg/dL or above

Glucose tolerance test (GTT)

The GTT, also known as the oral glucose tolerance test (OGTT), measures blood sugar levels before and after drinking a liquid that contains a certain amount of sugar, usually 100 grams. Before the test, fasting blood sugar levels are measured. Then, blood sugar levels are measured two hours after the drink is consumed. In some cases, blood sugar levels may be monitored throughout the two-hour interval and one or two hours after the drink is consumed. In addition to measuring glucose levels at different points during this period, the GTT may also measure insulin levels.

The blood sugar ranges for a diabetes diagnosis with a GTT are:

• Normal: 140 mg/dL or below
• Prediabetes: 140 – 199 mg/dL
• Diabetes: 200 mg/dL or above

Random blood glucose test

A random blood glucose test is a non-fasting blood test. In other words, it can be taken at any time throughout the day without the need for fasting. The most common reason for this type of test is to assess high glucose levels in people who are currently experiencing serious symptoms of diabetes. 

The blood sugar ranges for a diabetes diagnosis with a random plasma glucose test are: 

• Diabetes: 200 mg/dL or above

A1C test

Hemoglobin is a protein attached to the red blood cells in the body that can become coated with sugar. Also known as the hemoglobin A1C or HbA1c test, an A1C test measures average blood glucose levels over the past three months. It is used to help diagnose diabetes and monitor blood sugar control in people already diagnosed with diabetes. As with other blood sugar tests, the results of this test can be used to help predict the risk of eye, kidney, or nerve damage; heart attack and stroke; and other complications of diabetes.

The blood sugar ranges for a diagnosis of diabetes with an A1C test are:

• Normal: Below 5.7%
• Prediabetes: 5.7% – 6.4%
• Diabetes: 6.5% or above

Other diabetes and health tests

While diabetes is primarily diagnosed through a few blood tests, other tests may be useful for identifying any complications of diabetes, ruling out other conditions, and monitoring the progress of diabetes. 

Urine test

The urine test has been used to check for excess glucose in the urine. However, the results of a urine glucose test are not as accurate as those of a blood test. It may be used in some people who can’t tolerate a blood glucose test. A urine glucose test can also be used as part of a general health check-up. It can identify high levels of ketones in the urine, which can occur when there isn’t enough insulin and stored fat begins breaking down into ketones.

Eye test

Diabetes can damage the nerves and blood vessels in the eye. Damage to the eye can lead to blurred vision or complete vision loss. An eye specialist can evaluate the eyes and check for any eye problems in the blood vessels or back of the eye. People with diabetes should have their eyes checked regularly. 

At-home tests

At-home diabetes tests may be available to check or monitor blood sugar levels. You can buy over-the-counter tests, including ones that measure fasting blood glucose and A1C levels. One example is the finger-prick test. However, at-home tests may not be as accurate as those conducted in a doctor’s office or laboratory. 

Prevention of diabetes

Type 2 diabetes is a complex disease that can often be preventable. You may be able to prevent or delay the progression of diabetes with lifestyle changes, including eating a healthy diet and exercising regularly.

Diet

Diet is one of the most important ways to manage blood sugar levels. A dietary plan should be balanced, with a focus on whole foods in moderate portions. Avoid processed foods and sugary drinks.

Exercise

Regular exercise can help with weight loss and controlling blood sugar levels. Experts recommend 30 minutes or more of aerobic exercise three times per week at a moderate intensity. Examples of healthy exercises include swimming, cycling, and running. 

Quitting smoking

Smoking has been linked to an increased risk of diabetes, especially in heavy smokers. Smoking may affect how well insulin is able to work, leading to insulin resistance. Quitting smoking may help reduce the risk of diabetes over the long run. 

Takeaway

A blood test for diabetes is often performed during routine annual visits. However, some people with a high risk may need to be screened earlier or more often than others. There are several different types of tests that can measure blood sugar levels and aid a healthcare provider in diagnosing diabetes. If you have concerns about blood sugar levels and getting screened for diabetes, consult a healthcare provider. While diabetes can cause severe complications if left untreated, it may be preventable and easily managed.