Birth weight and childhood onset type 1 diabetes: population based cohort study

Abstract

The work of McCarron et al has provided clear evidence that substantial changes in blood pressure levels can occur, and both these and other data suggest that such changes can occur in broad population groups. New epidemiological studies that provide reliable information about the most likely causes of these changes, and new large scale randomised trials that identify effective means of changing population levels of blood pressure, are needed. To have the greatest impact on the global burden of cardiovascular disease, however, the data from such studies must be directly applicable to the social, cultural, and economic circumstances of the less affluent sections of the global community.Competing interests: None declared. 2 An association between high birth weight or high birth weight for gestational age and increased risk of type 1 diabetes has been found in some relatively large case-control studies, even after exclusion of data from children whose mother had diabetes in pregnancy.3-5 On the other hand, several other case-control studies have not found any significant association. [6][7][8][9][10][11][12][13][14] The magnitude of the association between birth weight and type 1 diabetes seems to be relatively small, and the lack of significant association in the latter studies may be explained by insufficient statistical power. We estimated the associations between birth weight and gestational age and the incidence rate of type 1 diabetes in a large population based cohort study that provided sufficient power to estimate these associations over a wide range of values. Participants and methods ParticipantsSince the beginning of 1989 all newly diagnosed cases of type 1 diabetes diagnosed in children aged up to 15 years in Norway have been prospectively registered with a high level of ascertainment in the National Childhood Diabetes Registry. 15 We designed a cohort study by record linkage of the Medical Birth Registry of Norway and the childhood diabetes registry through the unique personal identification number assigned to all residents of Norway. Out of 1863 cases of type 1 diabetes diagnosed between 1 January 1989 and 31 December 1998, 1824 were linked. All live births in Norway between 1974 and 1998 contributed time under observation from birth to diagnosis of type 1 diabetes, age 15 years, or 31 December 1998, whichever occurred first. As registration of cases started in 1989, the time under observation was counted only from 1 January 1989 for those born before this date. Deaths in the first year of life were Papers

Children developing type 1 diabetes before 6 years of age have increased linear growth independent of HLA genotypes

“…MPH = SDS birth length or height−SDS MPH Diff., difference from study, care was taken to obtain the birth length and birthweight data from the growth curves maintained for each child by the Child Health Services. Several epidemiological studies have reported that type 1 diabetic children have a higher birthweight [10][11][12][13]. This was not observed in the present group of children developing diabetes before 6 years of age.…”

“…High birthweight has been reported as a risk factor for type 1 diabetes [10][11][12][13]. We have demonstrated that children born with type 1 diabetes high-risk HLA genotypes had an increased risk of high birthweight corrected for gestational age (i.e.…”

Fetal growth is increased by maternal type 1 diabetes and HLA DR4-related gene interactions

“…The associations, however, are somewhat contrary to expectations. Although the effects are relatively weak, high birthweight and increased childhood growth rates are postulated to increase the risk of type 1 diabetes [37][38][39]. Yet, despite their high birthweight and increased BMI during childhood, children of mothers with type 1 diabetes have a lower risk of type 1 diabetes than children of fathers with type 1 diabetes [40].…”

Diabetes-associated HLA genotypes affect birthweight in the general population

“…Children born large for gestational age (LGA) had a higher risk of type 1 diabetes later in childhood [15]. In one study the incidence of type 1 diabetes was found to increase almost linearly with birthweight (BW) [16].…”

“…LGA and other altered growth rates appear to be associated with type 1 diabetes risk [15,16,[23][24][25][26]. It is not clear whether islet autoantibodies are associated with LGA or growth, or whether the relationship between high BW and type 1 diabetes is a result of the same genes being associated with both increased risk for type 1 diabetes and high BW.…”