Table 1

Summary of study material

Twin pairs born 1953–82 registered in the new Danish Twin Register20 888
Twin pairs with IDDM identified by questionnaire:102
 One or both unwilling to participate39
 One twin partner had died7
 One twin partner had emigrated5
 No response in one twin partner3
Twin pairs investigated: 17 MZ pairs, 15 DZss pairs, and 16 DZos pairs48
Twin pairs excluded from paired analysis:
 Did not want pupils dilated (MZ)1
 Ocular trauma in one eye (DZos)1
 Corneal transplantation in one eye (DZss)1
Twin pairs in paired analysis: 16 MZ , 14 DZss, and 15 DZos pairs45
  • Of these, two twins (MZ + DZss) did not cooperate with ultrasonic measurements.