What Are the Possible Causes of Type 1 Diabetes?

A lot of research is being done in the diabetes field to find how to best treat type 1 diabetes (T1D), and perhaps even how to prevent and cure it. Some researchers believe that the causes first need to be identified. Yet, exactly what triggers the onset of T1D is still unclear, and there are various hypotheses. A majority of experts agree that for some, the onset of T1D is linked to a genetic predisposition, and that environmental factors are also likely involved, although they are much less defined.

Genetic predisposition

Type 1 diabetes is an autoimmune disease, which means that the immune system, instead of protecting the body against infections, attacks and destroys healthy body cells. Type 1 diabetes results from the destruction of insulin-producing beta cells in the pancreas. A genetic component inherited from the parents is generally one of the triggering factors of autoimmune diseases.

  • Family history: The child of a parent with T1D can have a genetic predisposition, which means that they’ll have a greater risk of having type 1 diabetes if one or both parents or their twin sibling have this condition. The odds of getting T1D are less than 1% when there is no family history, but they reach 3–5% if a parent has it and close to 50% if an identical twin has it.
  • Ethnicity: According to U.S. statistics, Caucasians are proportionally the most likely ethnic group to be diagnosed with type 1 diabetes. People of Chinese and South American descent are at the lowest risk. 

Environmental factors

Environmental factors are elements with a potentially modifiable source that doesn’t arise from factors that were present at birth. 

  • Viral infections (see our BETTER article): For someone with a predisposition, some viruses (e.g., rubella virus, coxsackie virus, mumps virus) could cause an abnormal immune response. This happens when the immune system attacks and destroys the pancreas’s beta cells instead of attacking the virus. This abnormal immune response could be due to similarities between the envelope of those viruses and the surface of the pancreas’s beta cells.
  • Early use of antibiotics: Swedish researchers found that the risk of getting T1D was greater among individuals who were administered antibiotics before the age of 1. However, this risk factor is controversial and is disproved in other studies with different results. 
  • Intestinal microbiota (see our BETTER article): The intestine naturally contains microorganisms—mostly bacteria–, called intestinal microbiota or intestinal flora. Its composition, which varies from person to person, is closely linked to diet. Researchers suggested that the intestinal microbiota could influence the immune system and trigger the onset of T1D in some people, meaning that diet could be a factor in the development of the condition. The link between diet and T1D is disputed, and unfortunately, preliminary studies on the late introduction of certain foods to children are inconclusive on the T1D prevention aspect. 
  • Vitamin D (see our BETTER article): Vitamin D has been proven to play an important role in the immune system. Researchers studied what role it plays in relation to T1D specifically and found that children under 18 years of age who live with T1D generally have a lower vitamin D level than other children. So, taking vitamin D supplements at a young age could potentially be a way to prevent T1D. 
  • Geography: Northern countries seem to have more T1D cases than southern countries. Some have suggested that this could be due to people living in colder temperatures spending more time in their homes and in enclosed public spaces, and therefore being more vulnerable to viral infections. This hypothesis is in line with those linked to genetic predispositions and vitamin D deficiency—people living in northern parts of the world generally have lower levels because they have less sun exposure.

Will it ever be possible to prevent type 1 diabetes?

The roles of the genetic and environmental factors discussed above are still only hypotheses and observations. The specific causes of T1D are still unclear.

As for prevention, research is still underway to identify T1D risk factors (e.g., modifying the immunization calendar to reduce viral infections, varied diet).

Identifying potential type 1 diabetes triggering factors is one of the main goals of the BETTER registry.  

Not registered yet? Sign up now!

References

  • Basina, M. (Ed.). (2019). What Triggers Type 1 Diabetes? Healthline. Retrieved from https://www.healthline.com/diabetesmine/what-triggers-type-1-diabetes#1
  • Bogun M.M., Bundy B.N., Goland R.S., Greenbaum C.J. C-Peptide Levels in Subjects Followed Longitudinally Before and After Type 1 Diabetes Diagnosis in TrialNet. (2020) Diabetes Care. doi:10.2337/dc19-2288
  • Knip M., Siljander H. (2016). The role of the intestinal microbiota in type 1 diabetes mellitus. Nature Reviews Endocrinology,12(3):154–167. doi: 10.1038/nrendo.2015.218
  • Miettinen, M. E., Niinistö, S., Erlund, I., Cuthbertson, D., Nucci, A. M., Honkanen, J., Virtanen, S. M. (2020). Serum 25-hydroxyvitamin D concentration in childhood and risk of islet autoimmunity and type 1 diabetes: the TRIGR nested case–control ancillary study. Diabetologia, 63(4), 780–787. doi: 10.1007/s00125-019-05077-4
  • Triolo, T. M., Fouts, A., Pyle, L., Yu, L., Gottlieb, P.A., Steck, A.K. (2019). Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes, Diabetes Care, 42(2) 192–199; doi: 10.2337/dc18-0288
  • Type 1 Diabetes Risk Factors. (n.d.). Retrieved May 21, 2020, from https://www.endocrineweb.com/conditions/type-1-diabetes/type-1-diabetes-risk-factors
  • Wernroth, M.-L., Fall, K., Svennblad, B., Ludvigsson, J. F., Sjölander, A., Almqvist, C., and Fall, T. (2020). Early Childhood Antibiotic Treatment for Otitis Media and Other Respiratory Tract Infections Is Associated With Risk of Type 1 Diabetes: A Nationwide Register-Based Study With Sibling Analysis. Diabetes Care, 43(5), 991–999. doi: 10.2337/dc19-1162