National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Diabetes mellitus type 1

Not a rare disease Not a rare disease
Other Names:
Diabetes mellitus, insulin dependent; Type 1 diabetes; Insulin-dependent diabetes mellitus; Diabetes mellitus, insulin dependent; Type 1 diabetes; Insulin-dependent diabetes mellitus; IDDM; Juvenile-onset diabetes See More
Categories:
Diabetes mellitus type 1 (DM1) is a condition in which cells in the pancreas (beta cells) stop producing insulin, causing abnormally high blood sugar levels. Lack of insulin results in the inability of the body to use glucose for energy and control the amount of sugar in the blood. DM1 can occur at any age, but usually develops by early adulthood, most often in adolescence. Symptoms of high blood sugar may include frequent urination, excessive thirst, fatigue, blurred vision, tingling or loss of feeling in the hands and feet, and weight loss. The exact cause of DM1 is unknown, but having certain "variants" of specific genes may increase a person's risk to develop the condition. A predisposition to develop DM1 runs in families, but no known inheritance pattern exists. Treatment includes blood sugar control and insulin replacement therapy. Improper control can cause recurrence of high blood sugar, or abnormally low blood sugar (hypoglycemia) during exercise or when eating is delayed. If not treated, the condition can be life-threatening. Over many years, chronic high blood sugar may be associated with a variety of complications that affect many parts of the body.[1]
Last updated: 4/25/2014

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Autoimmunity
Autoimmune disease
Autoimmune disorder
[ more ] 		0002960
Decreased level of 1,5 anhydroglucitol in serum 0410050
Diabetes mellitus 0000819
Hyperglycemia
High blood sugar
0003074
Ketoacidosis 0001993
Polydipsia
Extreme thirst
0001959
Polyphagia
Voracious appetite
0002591
Polyuria
Increased urine output
0000103
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Last updated: 7/1/2020
Diabetes mellitus type 1 (DM1) itself is not inherited, but a predisposition to developing the condition can run in families. While some people with a family history of DM1 may be at an increased risk, most will not have the condition.

While the exact cause is not known, some genetic risk factors have been found. The risk of developing DM1 is increased by having certain versions (variants) of genes, which belong to a family of genes called the human leukocyte antigen (HLA) complex. HLA genes have many variations, and people have a certain combination of these variations, called a haplotype. Certain HLA haplotypes are associated with a higher risk of developing DM1, with particular combinations causing the highest risk. However, these variants are also found in the general population, and only about 5% of people with the gene variants develop DM1. Other genes, as well as a variety of other factors, are thought to influence the risk for DM1 also.[1]

Because there is no specific inheritance pattern associated with DM1, it is difficult to predict whether another family member will develop the condition. Generally, the risk is higher if a parent or sibling is affected. In some cases, genetic testing can be done to determine if someone who has a family history is at increased risk of developing the condition.[2] 

More information can be found on the America Diabetes Association's Web site, which has an article entitled Genetics of Diabetes.

People with specific questions about genetic risks to themselves or family members should speak with their health care provider or a genetics professional.
Last updated: 4/25/2014

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.
  • ClinicalTrials.gov lists trials that are related to Diabetes mellitus type 1. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • The Autoimmune Registry supports research for Diabetes mellitus type 1 by collecting information about patients with this and other autoimmune diseases. You can join the registry to share your information with researchers and receive updates about participating in new research studies. Learn more about registries.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • The American College of Obstetricians and Gynecologists (ACOG) created a publication on birth defects.  The pamphlet discusses ways in which a woman can decrease her chances of having a baby with a birth defect, including women who are pregnant and have diabetes. To read more about birth defects, visit the link below.
    Link: http://www.acog.org/publications/patient_education/bp146.cfm?printerFriendly=yes
  • Genetics Home Reference contains information on Diabetes mellitus type 1. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers. 
  • The National Diabetes Information Clearinghouse (NDIC) was established in 1978 to increase knowledge and understanding about diabetes among patients, health care professionals, and the general public. Click on the link to view information on this topic. 

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Diabetes mellitus type 1. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My wife's grandpa died of type 1 diabetes. My wife's younger sister has been diagnosed with type 1 diabetes at age 23. I'm worried that this will affect my kids. What are the possibilities or chances that my kids and their generations will have type 1 diabetes? See answer


  1. Type 1 diabetes. Genetics Home Reference. March, 2013; http://ghr.nlm.nih.gov/condition/type-1-diabetes. Accessed 4/25/2014.
  2. Type 1 diabetes. Mayo Clinic. January 23, 2013; http://www.mayoclinic.org/diseases-conditions/type-1-diabetes/basics/risk-factors/con-20019573. Accessed 4/25/2014.