A recent study suggests type I diabetes may be linked to time and place of birth. This is congruent with time and place clustering for a viral epidemic, and adds more weight to the growing theory that some cases of type I diabetes are caused by viral infection.
The study, which is published in the April 1996 Diabetes Care, looked at data from the Swedish Child Diabetes Registry. The registry keeps track of all cases of type I diabetes appearing before a child is 15. These cases were compared with the Swedish Medical Birth Registry, which assigns an identification number to every child born in Sweden, to develop a standard rate of type I development for the whole country. The country was then looked at in terms of municipalities, and the numbers were again compared. Each municipality was also compared by year and compared with the national average to look for groupings of cases.
Significant clusters were found in several municipalities on certain years, indicating a common cause or variable. According to G.G. Dahl-quist, one of the authors of the study, this same type of clustering is seen in viral epidemics. While this information does not confirm there is a viral cause for type I diabetes, it indicates a strong possibility.