Table 2.

Summary of studies investigating association of environmental factors in type 1 diabetes

Agent	Type of study	No of participants	Outcome
Enterovirus	Prospectivew1	155	Associated with diabetes autoantibodies
	Case-controlw2	260	In utero infection associated with type 1 diabetes
	Prospectivew3	65	No association with type 1 diabetes
Mumps	Case-controlw4	127	All these studies found associations with diabetes autoantibodies
Rubella	Retrospectivew5	386
Rotavirus	Case controlw6	54
Chickenpox	Prospectivew7	n/a
Cow's milk*	Prospectivew8	725	Positive association with autoimmunity
	Cross sectionalw9	253	Lack of association with autoimmunity
	Prospectivew10	317	Lack of association with autoimmunity
Common childhood vaccinations	Case-controlw11	3202	No association with autoimmunity
	Case-controlw12	317	No association with autoimmunity
	Prospectivew13	823	No association with autoimmunity
	Prospectivew14	4400	Positive association with autoimmunity
Nirates, nitrites, or nitrosamines	Prospectivew15	867	Both these studies showed circumstantial evidence suggesting an association between type 1 diabetes and consumption of food and water containing nitrates
	Retrospectivew16	1280

^*The data on cow's milk are conflicting. The TRIGR study (Finland) is under way to determine if elimination of cow's milk from infants' diet can prevent type 1 diabetes.