There are two types of diabetes, type 1 and type 2. Type 2, known as adult onset diabetes, usually occurs when the body becomes resistant to insulin, though in some cases it results from low production of insulin. In contrast, type 1 diabetes exclusively results from insufficient insulin production by the pancreas and is sometimes called insulin-dependent diabetes. Both types of diabetes are chronic diseases with no cure, though they can be managed to prevent the damage to the body that can occur without proper maintenance of blood sugar levels by insulin. Type 1, or juvenile diabetes, typically develops in childhood and is due to an autoimmune reaction. In this disease, the body’s own immune system attacks the cells of the pancreas, called beta cells, which make insulin. As these cells are damaged or destroyed, the ability of the pancreas to make insulin become permanently crippled. Type I diabetes has a genetic component and the predisposition can be passed on in families. Still, there is much evidence that development of the disease may need additional triggers in the environment, with viral infection being one of the major suspects. There may not even be a single cause, but rather a number of viral infections that could each trigger type 1 diabetes.
Among the candidate viruses being investigated is the rotavirus. Rotavirus is an extremely common childhood infection causing diarrhea and vomiting that can last for 3-8 days. It is easily spread among children in households, day care centers, and schools, with the vast majority of children having at least 1 infection by age 5. Over the last several years, a number of studies have strengthened the case that rotavirus may be at least one of several viruses to play a causal role in type 1 diabetes. Animal studies indicate that rotaviruses can replicate in pancreatic cells and can cause damage to this organ. Additionally, and perhaps more importantly where diabetes is concerned, is the possibility that rotavirus can induce the autoimmune response that leads to type 1 diabetes. A major protein that comprises the rotavirus particle shares some similarity to human proteins in the pancreas. This relationship led to the hypothesis that an immune response generated against a rotavirus infection could also cross-react with and attack the pancreas (see Honeyman, et al.).
The role of rotavirus in human type 1 diabetes was previously difficult to assess because the ubiquitous incidence of rotavirus infection meant that there were very few uninfected children to use as the control group. Fortunately, the widespread introduction of rotavirus vaccines since 2006 has now allowed an epidemiological evaluation of the impact of rotavirus prevention on type 1 diabetes incidence. An Australian study from early 2019 showed a decline in type 1 diabetes cases among children under 4 years of age coincident with the introduction of the rotavirus vaccine. In a subsequent US study looking at over 1 million infants, those who had completed the rotavirus vaccination schedule showed a 41% reduction in incidence of type 1 diabetes compared to unvaccinated children. Both of these studies support rotavirus infection as a contributor to development of at least some type 1 diabetes cases. It is important to note though that some children who were completely vaccinated against rotavirus still developed type 1 diabetes, so much more work needs to be done to understand risk factors and susceptibility to this disease. Still, potential prevention of type 1 diabetes appears to be a wonderful side benefit of this very safe and effective vaccine against a common childhood diarrheal disease.
As 2019 closes I just wanted to say happy holidays and best wishes for 2020 to all my friends, family, and readers. I probably won’t post again until January, but in the meantime if you have any scientific subjects you’d like me to report on next year feel free to send me ideas.