Abstract
Type 1 diabetes is a consequence of islet autoimmunity destroying the pancreatic beta cells. Its dramatic rise in incidence, having apparently non-genetic causes, has made it very important to investigate environmental factors whose modification could prevent the disease.
Here we review the disease incidence trends and periodicity, the genetic susceptibility, and selected non-genetic risk factors. There has been an enormous change over the past five decades in the exposure to microbial agents and their antigens: in particular, the use of antibiotics and improvements in hygiene and food safety have contributed to a decrease in the microbial load which in turn might have caused an increased risk of autoimmunity and allergy.
The research of infectious causes of diabetes started over 40 years ago using serology, it has boomed with the advent of PCR techniques and now it is fuelled by mass sequencing of the whole microbiome. Its results are discussed in connection with the changing landscape of infant and childhood gut flora.