Type 1 Diabetes

Type 1 diabetes: an introduction

Type 1 diabetes is an autoimmune disease, in which the body’s immune system, which under normal circumstances protects the body from invasion by foreign organisms or substances (such as bacteria or viruses), malfunctions.

In the case of type 1 diabetes, the body’s immune system attacks the beta cells in the pancreas that produce insulin, with the result that little or no insulin is produced. As with all types of diabetes, type 1 diabetes is characterized by high blood glucose, resulting from a lack of insulin production. Because a person with type 1 diabetes can not produce the insulin they need to use glucose, they must take insulin on a daily basis to keep their blood glucose levels in control and stay healthy.1

How is type 1 diabetes different from type 2 diabetes?

Although both type 1 and type 2 diabetes are characterized by elevated blood glucose or sugar, the cause behind this elevation is what distinguishes the two forms of diabetes. In type 2 diabetes, the body loses the ability to use the insulin it produces effectively (this is called “insulin resistance”). Loss of the ability to produce insulin also plays a role in elevated blood glucose in type 2 diabetes. Insulin resistance does not play a role in type 1 diabetes. In type 1 diabetes, an autoimmune process compromises the ability of the pancreas to produce insulin.2,3

In addition to the mechanisms that cause the two most common forms of diabetes, type 1 and 2 diabetes are also distinguished from one another in other important ways. People with type 1 diabetes are typically thin, whereas being overweight or obese is closely linked with type 2 diabetes.

Because type 1 diabetes is an autoimmune disease a type of specialized protein called an autoantibody that has been created to attack and destroy beta cells is present in the blood. This autoantibody is not found in people with type 2 diabetes. Other features that distinguish type 1 diabetes from type 2 diabetes include insulin dependence (type 1 diabetes requires treatment with insulin, while 30% to 40% of people with type 2 diabete require insulin). Without taking insulin, a person with type 1 diabetes is at increased risk for a complication called ketoacidosis.4

Comparing features of                           Type 1 and 2 diabetes


Type 1 diabetes

Type 2 diabetes

Age at diagnosis Typically younger than 25 years (may occur at any age) Typically older than 25 years*
Weight Typically thin Most (more than 90%) overweight or obese
Autoantibodies Present Absent
Insulin dependent Yes Yes
Insulin sensitivity Normal when controlled Decreased
Family history Infrequent (5% to 10%) Frequent (75% to 90%)
Risk of diabetic coma (ketoacidosis) high Low

*Frequency of type 2 diabetes is increasing in adolescents with increasing rates of obesity.

Adapted from McCulloch DK. Classification of diabetes mellitus and genetic diabetic syndromes. Nathan DM, Wolfsdorf JI, Mulder JE, eds. UptoDate. Wolters Kluwer Health. Accessed at: www.uptodate.com. 2013.

Exact cause remains a mystery

Like with many autoimmune diseases, the exact cause of type 1 diabetes is not known. However, scientists have identified a number of suspect factors that may play a role in causing the body’s immune system to attack beta cells in the pancreas. The list includes genetics (certain inherited genes that make a person more susceptible to the disease) and environmental factors, including (possibly) exposure to a virus.1

Symptoms of type 1 diabetes

The symptoms of type 1 diabetes include increased thirst and urination, weight loss, constant hunger, blurred vision, and severe fatigue. These symptoms typically appear over a short period of time. However, the process of destruction of beta cells in the pancreas may precede symptoms by years. Timely detection, diagnosis, and treatment of type 1 diabetes is of crucial importance, because without treatment with insulin, a person with the disease is at risk for lapsing into ketoacidosis.1

How is type 1 diabetes treated?

Type 1 diabetes is treated in two main ways, by measuring blood sugar regularly to monitor how high or low it is and by taking insulin (either in the form of injections or using a pump device that automatically supplies insulin subcutaneously to adjust blood sugar to a healthy level. Another important part of treatment for a person with type 1 diabetes, is the careful planning of meal and activities. Meals will raise blood sugar and physical activity will generally lower it, so it’s important to be prepared to take insulin or eat a meal to make sure that your blood sugar stays at a healthy level.5.5

Research in type 1 diabetes

Ongoing research in type 1 diabetes is seeking to better understand the causes and progression of the disease and how to prevent it in people who are at risk. Additional research is focused on ways to protect and preserve the function of beta cells in the pancreas in people who have been recently diagnosed with type 1 diabetes. Much of this research is being done through Type 1 Diabetes TrialNet, a global network of researchers and research facilities located in the US, Canada, Europe, and Australia. For information about TrialNet research initiatives, including participation in TrialNet clinical trials, visit www.DiabetesTrialNet.org (phone: 1-800-HALT-DM1 [425-8361]).

Written by: Jonathan Simmons | Last reviewed: May 2014.
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