Type 1 versus type 2 diabetes

Diabetes is a disorder that occurs when the pancreas is no longer able to make sufficient insulin, or when the body cannot make good use of the insulin it produces. This inhibits the control of blood glucose (sugar) levels and leads to raised blood glucose (hyperglycemia), which causes damage to various tissues and organs in the body.

What exactly is insulin?
Insulin is an essential hormone (messenger molecule) normally produced by the beta cells in the pancreas. It controls the amount of glucose in the bloodstream, helps move that glucose into the liver, fat, and muscles, and regulates the metabolism of carbohydrates, fats, and proteins (1).

What happens if there is not enough insulin?
When the body doesn’t produce enough insulin (or the cells do not respond properly to the available insulin), blood glucose levels increase. The cells around the body also don’t receive the energy that they would normally obtain from blood glucose, so fatigue and weakness can occur. Weight loss may also occur if the body seeks energy from other tissues instead (e.g., fat and muscle) (2).

How do insulin production and response differ in type 1 and type 2 diabetes?
Type 1 diabetics cannot produce insulin, so that essential hormone is absent and there is no control of blood glucose levels. Type 1 diabetes is due to an autoimmune reaction that targets the body’s own insulin-producing cells in the pancreas.

Type 2 diabetics can produce insulin but cannot use it efficiently, so blood glucose levels are not controlled properly. Type 2 diabetes is commonly caused by lifestyle factors, such as obesity, inactivity, smoking, and high cholesterol (3).

Are the symptoms the type 1 and type 2 diabetes the same?
Yes, generally the same symptoms occur in both types of diabetes. Symptoms can include:

  • Frequently very thirsty and hungry
  • Frequent urination
  • Fatigue
  • Blurry vision
  • Cuts or sores that don’t heal properly or take a long time to heal
  • Mood changes
  • Numbness and tingling in hands and feet

When do symptoms appear?
Although type 1 and type 2 diabetics share the same symptoms, the onset of these symptoms varies a lot. Symptoms in a type 1 diabetic usually develop quickly, over just a few weeks, with symptoms usually appearing in childhood or adolescence. In contrast, type 2 diabetics develop symptoms over many years (usually in adulthood), or they may not even experience any noticeable symptoms until other health complications occur (4).

Are type 1 and type 2 diabetes caused by the same factors?
No, the causes are quite different.

Type 1 diabetes occurs due to an aberrant immune response. Basically, the body’s own immune cells target and destroy the insulin-producing beta cells in the pancreas. These are the only cells in the body that can produce insulin, so when they are destroyed, there is a complete absence of insulin production (5). The underlying cause of this aberrant immune response is not fully understood. It could be due to genetic factors and environmental factors, such as exposure to a virus that affects how the immune system responds.

Type 2 diabetes is predominantly caused by lifestyle factors, with some genetic variation also playing a role in the risk of this common disorder. Lifestyle factors that increase the risk of type 2 diabetes include obesity, high blood pressure, alter lipid levels (e.g., high LDL “bad” cholesterol), lack of physical activity, and smoking (3).

How common are type 1 and type 2 diabetes?
Type 2 diabetes is much more common than type 1 diabetes. Type 2 diabetes accounts for 90–95% of all diabetics, which in the United States equates to 30–32.5 million people! And there are another 88 million adults in the United States who have prediabetes, which is when blood glucose is higher than normal but not as high as a diabetic. Prediabetes can be thought of as the first step down the path to type 2 diabetes (6).

How are type 1 and type 2 diabetes diagnosed?
The same blood tests are used for the diagnosis of both type 1 and type 2 diabetes. An HbA1c test is commonly used. This test measures your levels of glycated hemoglobin, which provides an average blood glucose level for the previous 2–3 months. We offer an HbA1c test from a small blood sample collected from a self-collected finger prick. More information about our HbA1c test is also available here.

Alternatively, a blood glucose test can be taken. A blood sample for a glucose test is commonly collected after a period of fasting (usually overnight). We offer a blood glucose test here.

1. Jaffe L & Hess-Fischl A. (Updated October 2021). What is insulin? Endocrine Web.
2. What is insulin? (Updated Nov 2018) Hormone Health Network.
3. What causes diabetes? Find out and take control. American Diabetes Association.
4. Diabetes Symptoms. CDC. April 2021.
5. What is Diabetes. CDC. June 2020.
6. National Diabetes Statistics Report, 2020. CDC. Reviewed August 2020.