Searching for the Causes of Type 1 Diabetes

Type 1 diabetes, also known as insulin dependent diabetes as well as juvenile diabetes, is considered to be a chronic health condition for which there is currently no cure. However, individuals with type 1 diabetes can successfully manage their diabetes and live very normal, active and fulfilling lives. Often type 1 diabetes is diagnosed when the individual is young, hence the earlier name of juvenile diabetes, but it can also occur as the individual ages based on a variety of different factors.

Like type 2 diabetes, the incidence rate for type 1 diabetes continues to rise but remains steady at about five to ten percent of all cases of diabetes diagnosed. There is a strong link between a specific genetic factor, the HLA (human leukocyte antigen) complex, and the development of type 1 diabetes but the specific trigger that causes the condition to occur is not clearly understood. 1

Genetic Factors

The HLA complex, the human leukocyte antigen, is actually a group of different genes that are all part of a larger group known as the major histocompatability complex, (MHC Class ll) which contains one specific gene, the IDDM1. When specific mutations of this gene are found within an individual or a family and closely mimic the actual MHC genes they are seen by the body as antigens.

Once the antigens are present the immune system then makes antibodies to fight the antigens, which in essence cause the body to attack the normal, necessary cells as if they were foreign cells. This particular reaction causes the immune system to attack the islet cells in the pancreas that produce the insulin required to regulate blood glucose levels. Once the genetic trigger has occurred, the process is irreversible.

In studies that traced the relationship between families and the development of type 1 diabetes some interesting results were discovered. First degree relatives, often known as blood relatives since they are siblings, parents or children of the person with type 1 diabetes, had a higher rate of islet-cell antibodies and a lower rate of insulin response. This showed a clear predisposition to the development of insulin-dependent diabetes mellitus. 2

More recent studies included the relationship between type 1 diabetes and extrapancreatic autoimmune disorders in first degree relatives. The results showed the first degree relatives of those young subjects diagnosed with type 1 diabetes had a 25% higher prevalence of autoimmune thyroiditis as well as a 8.3% higher rate of celiac disease. In addition, any subject that had an additional autoimmune disease and type 1 diabetes led to an increase in the prevalence of those conditions within the first degree relatives.3

Viruses and The Development of Type 1 Diabetes

Although not universally accepted in the medical field, many researchers believe there is a link between the development of type 1 diabetes and being exposed to specific viruses during an individual’s life. These viral exposures are most common with young children but can also occur in older children, teens and adults. The most commonly discussed virus that may link to type 1 diabetes include The Coxsackie virus. It is known to trigger autoimmune responses that cause the body to produce antibodies that destroy the beta cells in the pancreas that produce insulin. However, most children that develop any form of the Coxsackie virus will not develop type 1 diabetes. Those with a HLA variation that includes DR3 and DR4 that also develop the Coxsackie virus are at greatest risk.

Research into mouse populations infected with the Coxsackie virus tend to support the fact that the virus does not trigger the development of type 1 diabetes, but it can speed up the process if the antigens are already in place. This would tend to suggest that the timing of the infection with the virus is more important that the infection with the virus itself. 4

The other major virus that is associated with the increased risk of developing type 1 diabetes is the common German measles virus Rubella. Studies in Europe have linked blood group incompatibility between the baby and the mother as well as older maternal age, neonatal respiratory disease, jaundice and preeclampsia as significant risk factors for the development of type 1 diabetes. 5

Environmental Factors

Different environmental factors have been proposed as possible causes of higher rates of type 1 diabetes within specific populations. Two different issues that are currently under study include the feeding of cow’s milk, specifically the proteins contained within the milk, to very young infants. Other studies are tracing the increased rate of type 1 diabetes in children and adults that have a chronic deficiency of Vitamin D. 6

As indicated in the research study that compared various autoimmune disorders, wheat consumption may also play a role in the development of type 1 diabetes if specific genetic factors already exist. The development of celiac disease with type 1 diabetes is not clearly understood, but there are an increased number of individuals with type 1 diabetes being diagnosed with celiac disease than found in the non-diabetic population.

Although not a common cause, various medications may induce the destruction of the pancreatic cells. This is most commonly seen in the treatment of pancreatic cancer were chemotherapy drugs may destroy both the cancerous and healthy islet cells in some patients.

Damage to the pancreas through any type of disease other than cancer can reduce or completely destroy the ability of the pancreas to produce insulin. These disease factors are considered to be irreversible damage and patients will need to rely on insulin to regulate their blood sugar throughout life. Tumors or any type of physical injury, most commonly noted with vehicle accidents or other types of falls and accidents can lead to decreased functioning of the pancreas and resulting diagnosis of type 1 diabetes.

References

1 Daneman, D. (2006). Type 1 diabetes. The Lancet , 847-858.

2 Srikanta, S., Ganda, O. P., Rabizadeh, A., et al. (1985). First-Degree Relatives of Patients with Type I Diabetes Mellitus — Islet-Cell Antibodies and Abnormal Insulin Secretion. The New England Journal of Medicine , 461-464.

3 Hanukoglu, A., Mizrachi, A., Dalal, I., et al. (2003). Extrapancreatic Autoimmune Manifestations in Type 1 Diabetes Patients and Their First-Degree Relatives. Diabetes Care , 1325-1340.

4 Serreze, D. V., Ottendorfer, E. W., Ellis, T. M., et al. (2000). Acceleration of type 1 diabetes by a coxsackievirus infection requires a preexisting critical mass of autoreactive T-cells in pancreatic islets. . Diabetes , 708-711.

5 Dahlquist, G. G., Patterson, C., & Sotesz, G. (1999). Perinatal risk factors for childhood type 1 diabetes in Europe. The EURODIAB Substudy 2 Study Group. Diabetes Care , 1698-1702.

6 Akerblom, H. K., Vaarala, O., Hyoty, H., et al. (2002). Environmental factors in the etiology of type 1 diabetes. American Journal of Medical Genetics , 18-29.

This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.