Birth weight and childhood onset type 1 diabetes: population based cohort study
BMJ 2001; 322 doi: https://doi.org/10.1136/bmj.322.7291.889 (Published 14 April 2001) Cite this as: BMJ 2001;322:889
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Dear Editor,
I found the article by Stene et al1 interesting, and the findings in relation to birth weight and subsequent development of childhood onset type 1 diabetes suprising. My own work in this field looked at the incidence of abnormal glucose tolerance tests in women during pregnancy and related it to maternal birth weight.2 In this work 592 pregnant women were studied. Plasma glucose concentrations were found to fall with increasing birth weight, and those women at highest risk of developing glucose ‘intolerance’ or gestational diabetes were those with a low birth weight, or a high adult body mass index.
The conclusion of this study was that long term intra-uterine ‘starvation’ caused a depletion of the ?-cell population of the islet of Langerhans as a result of fetal cerebral haemodynamic adaptation.3,4 The findings of the study by Stene et al1 shows that the association between birth weight and type 1 diabetes is reversed, and thus suggests a different aetiology. The common thread, however, is the importance of the perinatal environment on childhood and adult disease. The onus still lies, therefore, with those clinicians involved in obstetric and perinatal care to continue research into the optimal management of the at-risk fetus, not only the growth retarded but also the macrosomic.
Kárl S. Oláh,
Consultant and Honorary Senior Lecturer in Obstetrics & Gynaecology,
Warwick & Stratford Hospitals,
South Warwickshire NHS Trust,
Warwickshire
References
1.Stene, L.C., Magnus, P., Lie, R.T., SØvik, O., Joner, G. & The Norwiegian Childhood Diabetes Study Group. Birth weight and childhood onset type 1 diabetes: population based cohort study. BMJ 2001;322:889-892.
2. Oláh, K.S. Low maternal birth weight – an association with impaired glucose tolerance in pregnancy. J Obstet Gynaecol 1996;16:5-8.
3. Arduini, D. and Rizzo, G. Prediction of fetal outcome in small for gestational age fetuses: Comparison of Doppler measurements obtained from different fetal vessels. J Perinat Med. 1992;20:29-38.
4. Gramellini, D., Folli, M.C., Raboni, S., Vadora, E. and van-Doesburg, N.H. Fetal central blood flow alterations in human fetuses with umbilical artery reverse diastolic flow. Am J Perinat 1993;10:197-207.
Competing interests: No competing interests
EDITOR-Stene et al have reported that the incidence of type 1
diabetes increased with increasing birth weight, independent of
gestational age, maternal diabetes, and other potential confounders.[1]
We
assessed the birth weight in 32 children and adolescents with clinical
onset of type 1 diabetes at 3 months to 17 years of age (mean, 7.2 years)
and in their 46 healthy siblings, compared with 905 healthy children-
residents of the same area. Children with diabetes were identified between
1986 and 2001 in the well-defined area of the island of Crete using the
Paediatric Diabetes Clinic Register at the University Hospital, Heraklion.
We requested permission from parents of children with diabetes and who
also had healthy siblings. We retrieved weights recorded in the child’s
health booklet which is kept for each child in Greece. We used the
reference values of non-immigrant Cretan children [2] to compute standard
deviation score (SDS, z score) for every child. The weight z score for a
certain individual was calculated as the difference in weight of the
individual (W) and the mean weight in the studied population
() divided by the population standard deviation
(): z score=(W-)/. The mean standard
deviation scores in diabetic children (+SD) and their siblings were 0.228
(+0.766) and 0.192 (+0.833) respectively. No statistically significant
difference was documented between the two groups (2-tailed T test,
P=0.827).
As stressed by Stene et al, results of case-control studies of birth
weight and risk of type 1 diabetes have been inconsistent, and both
studies suggestive of an association between high birth weight and
increased risk of type 1 diabetes and studies indicating no significant
association have been published1. Stene et al propose that the lack of
significant association in the latter studies may be explained by
insufficient statistical power. However, even in their large study the
increment in risk with increasing birth weight was still relatively low.
In our small study no indication was found that heavier newborns are at
additional risk for developing juvenile type 1 diabetes.
Dimitris Mamoulakis
consultant paediatrician
Ilianna Maniadaki
paediatric senior house officer
Stelios Bicouvarakis
paediatric senior house officer
Emmanouil Galanakis
assistant professor of Paediatrics
Department of Paediatrics, University Hospital of Crete, POB 1352, 71110
Heraklion, Greece
egalanak@med.uoc.gr
1 Stene LC, Magnus P, Lie RT, Sovik O, Joner G. Birth weight and
childhood onset type 1 diabetes: population based cohort study. BMJ
2001;322:889-92.
2 Linardakis M, Moschandrea I, Kafatos A. Growth curves of infants and
preschool age children from Crete which resulted from longitudinal study.
Paediatriki 2000;63:391-407.
Competing interests: No competing interests
I read this article with interest. The proportion of Norwegian
babies with birth weights over 4000 grams is rising noticeably, and we
don't know why. Weights at all gestational ages seem to be increasing.
The diet of young people in Norway is calorically much more than adequate
but the composition thereof has taken many turns for the worse in the past
decade.
I was surprised that the word breastfeeding did not occur anywhere in
this article. For many years babies with birth weights of 4 kg and more
have been at high risk for cow's milk exposure (in industrially prepared
breastmilk substitutes), often on the orders of Norwegian pediatricians
who doubt the adequacy of breastfeeding for such large babies in the first
few days of life. Banked human milk is in limited supply and tends to go
to the youngest and smallest babies, not to the big bruisers in the
highest weight groups. It has been speculated that early exposure to
cow's milk may be associated with a higher risk of type 1 diabetes in
childhood.
The authors of the current study ought to be familiar enough with the
practices mandated by their colleagues to at least mention the possibility
that birth weight may merely be a risk factor for iatrogenic injury
leading to diabetes. Norway is a tiny country, and while newborn care
policies vary slightly from unit to unit, for all practical purposes we
have a very uniform maternity care system.
I realize that the increased rate of artificial feeds would not
explain why low birth weight babies have a lower rate of type 1 diabetes
arising in their first 15 years of life, as they are also at high risk for
supplemental and pre-lacteal feeds. The authors themselves postulate that
the immature immune systems of these babies may be protective in some way,
and perhaps that has something to do with it.
I would be very interested to see research directed at the feeding
histories for the first week of life for cases and appropriate cohort
controls from the groups in this study.
Rachel Myr
Kristiansand, Norway
Competing interests: No competing interests
Diabetes and Birth Weight: MoreConfounding Factors
Diabetes and Birth Weight: More Confounding Factors
EDITOR- Stene et al (1) found a weak relationship between increased
birth weight and development of type 1 diabetes. The main strength of this
comprehensive study is the large population base used, though obviously on
this scale it was difficult for them to address other variables in detail.
In the analysis of their results, the authors address a number of
confounding factors. Their conclusions remained valid after they had
accounted for these, which included maternal age, maternal diabetes
mellitus and sex of the baby. However, we would like to suggest some
additional confounders which could be relevant to further research.
In their own conclusions, the authors noted that they were unable to
take into account socio-economic factors such as maternal education and
smoking. These are potentially modifiable elements which may impact both
on birth weight and risk of developing diabetes.
It would be helpful to look at some of the factors considered in the
paper in greater detail. For example, it may be relevant to take into
account extremes of maternal age and parity. Also in this vein the effect
of assisted deliveries other than caesarean and seasonality of births
could be analysed.
In addition, further studies could address elements of co-
morbidity and paternal influence. Aspects of diet, including maternal
diet, breast feeding and special care nutrition, could have influences on
the development of diabetes.
Further research is required to clarify these issues and to give this
valuable study clinical application.
Lorna Mulholland, Janet Purcell, Tim Shipley, Wen Loh
3rd Year Medical Students, Department of Epidemiology and Public
Health, University of Newcastle-upon-Tyne
1: Stene, L.C., Magnus, P., Lie, R.T., Sovik, O, Joner, G. and the
Norwegian Childhood Diabetes Study Group; Birth Weight and childhood onset
type 1 diabetes: population based cohort study; BMJ 2001;322: 889-892
Competing interests: No competing interests