Inverse relationship between allergic contact dermatitis and type 1 diabetes mellitus: a retrospective clinic-based study.
OBJECTIVE
Contact allergy (CA) is a disease induced and maintained by environmental factors, which mainly has a Th2 pattern in its chronic form. Environmental factors play a major role in CA, while genetic factors are of minor importance. Type 1 diabetes is an autoimmune disease of the islets of Langerhans, which has a Th1 cytokine pattern and in which modulators of risk are both genetic and environmental. To investigate whether environmental exposure to chemicals leading to CA could influence the risk of type 1 diabetes, we conducted a retrospective clinic-based study of patients subjected to diagnostic patch testing of CA.


METHODS
We undertook a retrospective clinic-based study of 13,315 patients who were patch-tested between 1985 and 2003, and linked it with the Danish National Patient Registry containing diabetic mellitus discharge diagnoses from 1987 to 2003. The 13,315 patch-tested patients gave rise to 4,848 CA patients. Using logistic regression, we calculated odds ratios for persons with CA of having type 1 diabetes.


RESULTS
Type 1 diabetes was diagnosed in 229 of the patch-tested patients. CA patients had a reduced risk of having type 1 diabetes, with an odds ratio 0.62 (95% CI 0.46-0.86). After adjusting for sex and age, the odds ratio was 0.63 (95% CI 0.47-0.86).


CONCLUSIONS
An inverse relationship between CA and type 1 diabetes was found. Thus there may be a protective effect of having CA in relation to the risk of type 1 diabetes, or vice versa type 1 diabetes may lead to tolerance rather than hypersensitivity. Alternatively, these two diseases may share common genetic factors, although at present these are unknown.
National Allergy Research Centre, Department of Dermatology, Gentofte Hospital, University of Copenhagen, DK-2820, Copenhagen, Denmark. kaaeng02@gentoftehosp.kbhamt.dk
K
K
Engkilde
T
T
Menné
J D
JD
Johansen
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D017449:Dermatitis, Allergic Contact / Q000150:complications* / Q000453:epidemiology / Q000473:pathology*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D012189:Retrospective Studies