Immunisation and type 1 diabetes mellitus - Is there a link?

Recent evidence from animal studies has raised the possibility that immunis ation by vaccines can influence the pathogenesis of type 1 (insulin-depende nt) diabetes mellitus. In non-obese diabetic mice and biobreeding rats, com plete Freund's adjuvant and bacillus Calmette-Guerin (BCG) vaccine have suc cessfully been used to interrupt the development of diabetes mellitus. This effect is probably mediated by nonspecific suppression of the autoimmune p rocess. A number of attempts have also been made to assess the impact of pa renteral immunisation on type 1 diabetes mellitus in humans. Epidemiological evidence has not indicated any clear link between BCG vacci nation and the development of diabetes mellitus in humans. Some reports hav e suggested that natural mumps or mumps vaccinations can induce islet cell autoimmunity, but there is no evidence that mumps-measles-rubella mass vacc ination programmes have changed the incidence of diabetes mellitus in any p opulation. An independent protective role of measles virus has been suggest ed in one study. Recent studies have indicated that enterovirus infections may induce beta cell autoimmunity and clinical diabetes. The only currently available enterovirus vaccine is the poliovirus vaccine which, in theory, could modulate the protection against other enteroviruses by inducing cross -reactive T cell immune responses; however, this hypothesis has not been te sted so far. In conclusion, there is no clear evidence that any currently used vaccine c an prevent or induce diabetes in humans. However, only a few studies are av ailable on the subject and therefore the possibility of a link between vacc ination and diabetes mellitus cannot be excluded.