What Causes Type 1 Diabetes in Adults?

Last Editorial Review: 5/10/2018

Ask the experts

My uncle has just been diagnosed with type 1 diabetes and I'm so worried for him. I thought that was an illness that starts in childhood. What causes type 1 diabetes in adults?

Doctor’s Response

Type 1 diabetes is caused by the autoimmune destruction of the pancreatic beta cells that produce insulin. It is not known why the autoimmune destruction happens. However, there are some known triggers, for example:

  • Genetics, including family history and the prenatal environment of the mother, can put you at risk for developing type 1 diabetes.
  • Exposures to chemicals, especially ones called endocrine disruptors, found in plastics
  • Viral infections also can trigger the autoimmune process.
  • Early or late introduction of certain foods to infants has been shown to trigger type 1 diabetes in research studies. Introducing fruit before 5 months of age or waiting until later than 7 months to introduce grains such as oats and rice increases the risk of diabetes. However, research shows that breastfeeding reduces these risks.

The underlying cause of type 1 diabetes usually is not known.

What are risk factors for developing type 1 diabetes?

Risk factors for developing type 1 diabetes include: prenatal exposures, exposures to foods and environmental toxins early in life, and geography.

  • Prenatal exposures include maternal had preeclampsia or metabolic syndrome .
  • Environmental exposures include chemicals, especially those found in plastics and foods, specifically introduction of gluten, casein (the protein in dairy) or fruit before four months of age or late introduction (after seven months of age) grains (gluten, oat, and rice) and casein.
  • Viral infections, such as Epstein-Barr virus or EBV (mononucleosis), Coxsackie, CMV, and other infections can also be risk factors for developing type 1 diabetes.
  • Living in a northern climate is a risk factor that has not been fully explained.

For more information, read our full medical article on type 1 diabetes.


Health Solutions From Our Sponsors


Akerblom HK, Vaarala O, Hyöty H, Ilonen J, Knip M. "Environmental factors in the etiology of type 1 diabetes." Am J Med Genet. 2002 May 30;115(1):18-29.

Antvorskov JC, Josefsen K, Engkilde K, Funda DP, Buschard K. "Dietary gluten and the development of type 1 diabetes." Diabetologia. 2014 Sep;57(9):1770-80.

Bodin J., et al. "Can exposure to environmental chemicals increase the risk of diabetes type 1 development?" Biomed Res Int. 2015;2015:208947.

Frederiksen, B., et al. "Infant Exposures and Development of Type 1 Diabetes Mellitus: The Diabetes Autoimmunity Study in the Young (DAISY)." JAMA pediatrics. 2013;167(9):808-815.

Morgan, MP., et al. "Imunogenetics of type 1 diabetes mellitus." Mol Aspects Med. 2015 Apr;42:42-60.

Moss SE, Klein R, Klein BEK, Meuer MS. "The association of glycemia and cause-specific mortality in a diabetic population." Arch Int Med 154:2473–2479, 1994.

Schuppan D, Hahn EG. "Celiac disease and its link to type 1 diabetes mellitus." J Pediatr Endocrinol Metab. 2001;14 Suppl 1:597-605.