This study was approved by the Institutional Review Board at the University of California at Los Angeles, the Danish Data Protection Agency (Ref no. 2008-41-2680) and the Ethics Committee for Central Jylland in Denmark (Ref no. M-20100252). Individual written consent was not obtained from study participants as there was no record linking the subjects to identifying information. Methods
described in this paper have been described elsewhere 
. In short, this study is a population-based follow-up study based on Danish national registers. We used data from the Danish Civil Registration System (CRS) to identify singleton births in Denmark born January 1st
1979 through December 31st
1,878,246 and linked them to their next of kin (mother, father, siblings, and mother’s parents). Since 1968, all live born children and new residents in Denmark are assigned a unique civil personal registration number, allowing for accurate linkage at the individual level between all national registries.
Information on birth outcomes, such as gestational age at birth and birthweight, were obtained from the Danish Medical Birth Registry which has been computerized since 1973. Annual information on maternal education, residence, and income was retrieved from the Fertility Database at Statistics Denmark, available since 1979. The date of conception was estimated by the date of birth minus gestational age, and the prenatal exposure period included from 12 months before conception until the birth of the child. We categorized children as exposed to bereavement during prenatal life if their mothers lost an elder child, husband or parent during the prenatal period; the remaining children were included in the unexposed cohort. All deaths were identified via the Death Registry which reports high validity on vital status 
. Cohort members were followed from birth until first diagnosis of diabetes, death, emigration, or December 31st
2008, whichever came first.
Diabetes in children and their parents was ascertained from the Diabetes and Hospital Registers. The National Hospital Register holds information on all discharges from Danish hospitals since 1977; outpatients have been included in the register since 1995. The Danish Diabetes Register was established in 2006 and also identifies individuals treated for diabetes outside of the hospital setting by combining data from the National Patient Register, the National Health Insurance Service Register and the Register of Medicinal Product Statistics 
. Individuals with a diabetes diagnosis from the Diabetes Register that did not have a hospital diagnosis for type-1 diabetes were assumed to have type-2 diabetes. Diagnostic information was based on the Danish version of the International Classification of Disease (ICD) 8th
revision, from 1979 to 1993 (250) and 10th
revision, from 1994 onwards (E11).
We estimated incidence rate ratios (IRRs) from birth using log-linear poisson regression models and used person-years as the offset variable. The analysis was performed using PROC GENMOD in SAS version 9.1.3. Unadjusted and adjusted models were generated. Adjusted estimates of IRR (aIRR) included maternal age (≤18, 19–34, 35–40, 41+); residence (Copenhagen, cities with over 100,000 inhabitants, and other); income (1st, 2nd, 3rd, and 4th quartile); maternal education (primary, secondary, high); parental diabetes status (any hospitalization diabetes ICD code); marital status (married, not married); sibling order (1,2,3,4+); calendar year (1979–1989, 1990–1999, 2000–2004, 2004–2008) and offspring’s sex (male, female). Age, residence, calendar period, maternal education, maternal income and parental marital status were treated as time-dependent variables.
To examine the association between timing of the bereavement and diabetes, we categorized exposed children by prenatal trimesters. To examine the relationship between type of bereavement and diabetes, we categorized exposed children by relationship to the deceased. We further categorized the cause of death by traumatic death (traumatic causes: ICD-8 codes 7950–7959, ICD-10 codes R95–R97; motor vehicle accidents: ICD-8 codes 8100–8230, ICD-10 codes V01–V89; suicide: ICD-8 codes 950–959, ICD-10 codes X60–X84; and other accidents and violence: ICD-8 codes 800–807, ICD-10 codes V90–V99, W00–X59, X85–Y89); and death from other causes.