Type 2 diabetes happens when your body can’t use insulin properly. Without treatment, Type 2 diabetes can cause various health problems, like heart disease, kidney disease and stroke. You can manage this disease by making lifestyle changes, taking medications and seeing your healthcare provider for regular check-ins.
What is Type 2 diabetes?
Type 2 diabetes (T2D) is a chronic condition that happens when you have persistently high blood sugar levels (hyperglycemia).
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Healthy blood sugar (glucose) levels are 70 to 99 milligrams per deciliter (mg/dL). If you have undiagnosed Type 2 diabetes, your levels are typically 126 mg/dL or higher.
T2D happens because your pancreas doesn’t make enough insulin (a hormone), your body doesn’t use insulin properly, or both. This is different from Type 1 diabetes, which happens when an autoimmune attack on your pancreas results in a total lack of insulin production.
Type 2 diabetes is very common. More than 37 million people in the U.S. have diabetes (about 1 in 10 people), and about 90% to 95% of them have T2D.
Researchers estimate that T2D affects about 6.3% of the world’s population. T2D most commonly affects adults over 45, but people younger than 45 can have it as well, including children.
Symptoms and Causes
Symptoms of Type 2 diabetes tend to develop slowly over time. It’s important to see a healthcare provider if you have them.

Is Type 2 diabetes genetic?
The cause of T2D is complex, but researchers know that genetics play a strong role. Your lifetime risk of developing T2D is 40% if you have one biological parent with T2D and 70% if both of your biological parents have it.
Researchers have identified at least 150 DNA variations linked to the risk of developing T2D — some increase your risk and others decrease it. Some of these variations may directly play a role in insulin resistance and insulin production. Others may increase your risk of T2D by increasing your tendency to have overweight or obesity.
These genetic variations likely act together with health and lifestyle factors to influence your overall risk of T2D.
Diagnosis and Tests
How is Type 2 diabetes diagnosed?
The following blood tests help your healthcare provider diagnose Type 2 diabetes:
• Fasting plasma glucose test: This lab test checks your blood sugar level. You typically need to get this test in the morning after an eight-hour fast (nothing to eat or drink except water). A result of 126 mg/dL or higher means you have diabetes.
• Random plasma glucose test: This lab test also checks your blood sugar, but you can get it at any time without fasting. A result of 200 mg/dL or higher means you have diabetes.
• A1C test: This lab test measures your average blood sugar levels over the past two to three months. A result of 6.5% or higher means you have diabetes.
In some cases, your provider may order an autoantibody blood test to see if you have Type 1 Diabetes instead of T2D.

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