Birthweight and risk of type 1 diabetes in children and young adults: a population-based register study

The countdown to type 1 diabetes: when, how and why does the clock start?

'The clock to type 1 diabetes has started when islet antibodies are first detected', commented George Eisenbarth with regard to the pathogenesis of type 1 diabetes. This review focuses on 'starting the clock', i.e. the initiation of pre-symptomatic islet autoimmunity/the first appearance of islet autoantibodies. In particular, this review addresses why susceptibility to developing islet autoimmunity is greatest in the first 2 years of life and why beta cells are a frequent target of the immune system during this fertile period. A concept for the development of beta cell autoimmunity in childhood is discussed and three factors are highlighted that contribute to this early predisposition: (1) high beta cell activity and potential vulnerability to stress; (2) high rates of and first exposures to infection; and (3) a heightened immune response, with a propensity for T helper type 1 (Th1) immunity. Arguments are presented that beta cell injury, accompanied by activation of an inflammatory immune response, precedes the initiation of autoimmunity. Finally, the implications for strategies aimed at primary prevention for a world without type 1 diabetes are discussed.

Epidemiologic Implication of the Association between Herpes Simplex Virus Infection and the Risk of Type 1 Diabetes Mellitus: A Nationwide Case-Control Study in Taiwan

Enterovirus infection is a known risk factor for type 1 diabetes (T1DM). Whether infection with other viruses induces T1DM remains undetermined. This study investigated the association between human herpesvirus (HHV) infection and the development of T1DM, using the data from Taiwan’s National Health Insurance Research Database. Patients with T1DM and age- and sex-matched controls were included. Subjects with HHV infection were subgrouped into those with histories of varicella-zoster virus, herpes simplex virus (HSV), Epstein-Barr virus, and human cytomegalovirus infections. The odds ratio of the risk of T1DM was calculated using a multivariable conditional logistic regression model. Atopic diseases, autoimmune thyroid diseases, and history of enterovirus infection served as adjusted comorbidities. Our findings suggested a significant association between HSV infection and the risk of T1DM (adjusted odds ratio: 1.21; 95% CI: 1.01–1.47, p = 0.048), while infection with other HHVs was not. The result of HSV infection remained significant when subjects were restricted to age ≤ 18 years (adjusted odds ratio: 1.35; 95% CI: 1.08–1.70, p = 0.010). We found a history of HSV infection might be an independent predictive risk factor for T1DM. This could be potentially helpful to the practice in public health.

Smoking in pregnancy is associated with increased adiposity and retinal arteriolar wall-to-lumen ratio in adolescence: The Copenhagen Child Cohort Study 2000

PURPOSE

To investigate the association between prenatal exposures and anthropometric data and cardiovascular risk factors including retinal arteriolar wall-to-lumen ratio in adolescence.

METHODS

This longitudinal observational study included all 1445 adolescents from the Copenhagen Child Cohort 2000 who attended the 2016-2017 examination. Outcome measures included retinal arteriolar wall-to-lumen ratio, height, body mass index, waist-to-hip ratio, body composition measured by bioimpedance, and blood pressure. Information on prenatal exposures (birth weight, gestational age, maternal smoking during pregnancy) as well as sex, parental age, household income and parental educational levels were obtained from national registries. Associations between exposures and outcome measures were analyzed using general linear models.

RESULTS

Maternal smoking during pregnancy was associated with a higher retinal arteriolar wall-to-lumen ratio (0.004 or 1.9%, P = 0.009) at age 16/17 years, an association driven exclusively by the female participants (0.008 or 3.7%, P < 0.0001). Maternal smoking during pregnancy was also associated to higher body-mass index (1.43 kg/m², P < 0.0001), waist-to-hip ratio (0.02, P < 0.0001) and fat mass index (0.93 kg/m², P < 0.0001). Birth weight, gestational age, and parental age had no detectable impact on retinal arteriolar wall-to-lumen ratios.

CONCLUSION

Prenatal exposure to tobacco smoking is associated with a higher risk of obesity and, predominantly in girls, to a greater retinal arteriolar wall thickness, which suggests that maternal smoking may induce an unfavorable cardiovascular and metabolic risk profile in the child.

Gestational respiratory infections interacting with offspring HLA and CTLA-4 modifies incident β-cell autoantibodies

β-cell autoantibodies against insulin (IAA), GAD65 (GADA) and IA-2 (IA-2A) precede onset of childhood type 1 diabetes (T1D). Incidence of the first appearing β-cell autoantibodies peaks at a young age and is patterned by T1D-associated genes, suggesting an early environmental influence. Here, we tested if gestational infections and interactions with child's human leukocyte antigen (HLA) and non-HLA genes affected the appearance of the first β-cell autoantibody. Singletons of mothers without diabetes (n = 7472) with T1D-associated HLA-DR-DQ genotypes were prospectively followed quarterly through the first 4 years of life, then semiannually until age 6 years, using standardized autoantibody analyses. Maternal infections during pregnancy were assessed via questionnaire 3-4.5 months post-delivery. Polymorphisms in twelve non-HLA genes associated with the first appearing β-cell autoantibodies were included in a Cox regression analysis. IAA predominated as the first appearing β-cell autoantibody in younger children (n = 226, median age at seroconversion 1.8 years) and GADA (n = 212; 3.2 years) in children aged ≥2 years. Gestational infections were not associated with the first appearing β-cell autoantibodies overall. However, gestational respiratory infections (G-RI) showed a consistent protective influence on IAA (HR 0.64, 95% CI 0.45-0.91) among CTLA4-(AG, GG) children (G-RI*CTLA4 interaction, p = 0.002). The predominant associations of HLA-DR-DQ 4-8/8-4 with IAA and HLA-DR-DQ 3-2/3-2 with GADA were not observed if a G-RI was reported (G-RI*HLA-DR-DQ interaction, p = 0.03). The role of G-RI may depend on offspring HLA and CTLA-4 alleles and supports a bidirectional trigger for IAA or GADA as a first appearing β-cell autoantibody in early life.

Environmental Risk Factors and Type 1 Diabetes: Past, Present, and Future

Type 1 diabetes is an autoimmune condition that results from the destruction of the insulin-producing beta cells of the pancreas. The excess morbidity and mortality resulting from its complications, coupled with its increasing incidence, emphasize the importance of better understanding the causes of this condition. Over the past several decades, a substantive amount of work has been done and, although many advances have occurred in identifying disease-susceptibility genes, there has been a lag in understanding the environmental triggers. Several putative environmental risk factors have been proposed, including infections, dietary factors, air pollution, vaccines, location of residence, family environment and stress. However, most of these factors have been inconclusive, thus supporting the need for further study into the causes of type 1 diabetes.

Maternal overweight and obesity are associated with increased risk of type 1 diabetes in offspring of parents without diabetes regardless of ethnicity

AIMS/HYPOTHESIS

The incidence of type 1 diabetes in children is increasing in Sweden, as is the prevalence of maternal overweight/obesity. Therefore, the aim of this study was to investigate if maternal overweight/obesity increases the risk of type 1 diabetes in offspring of parents with and without diabetes, and of different ethnicities.

METHODS

The study cohort comprised 1,263,358 children, born in Sweden between 1992 and 2004. Children were followed from birth until diagnosis of type 1 diabetes, emigration, death or end of follow-up in 2009, whichever occurred first. First trimester maternal BMI was calculated (kg/m(2)). Poisson regression was used to calculate incidence rate ratios (IRRs) with 95% CI for type 1 diabetes in the offspring.

RESULTS

The risk of type 1 diabetes was increased in offspring of parents with any type of diabetes regardless of parental ethnicity. High first trimester maternal BMI was associated with increased risk of type 1 diabetes only in offspring of parents without diabetes (IRR 1.33 [95% CI 1.20, 1.48]).

CONCLUSIONS/INTERPRETATION

Increasing incidence of type 1 diabetes in children with non-diabetic parents may partly be explained by increasing prevalence of maternal overweight/obesity.

[Epidemiology of diabetes in children in Languedoc-Roussillon (France)]

Since 1st January 2000, the PEDIAB-LR registry has listed new cases of diabetes in children under 16 years of age in the Languedoc-Roussillon region of France, in order to assess the incidence and epidemiological characteristics of children affected by diabetes. At the end of December 2010, 745 children had been registered. The characteristics of these children included an identical proportion of girls and boys, a mean age of 8 years at diagnosis, and a family history of type 1 diabetes in 8.4% of the cases. Inaugural ketoacidosis was observed in 69.5% of the patients and was severe in 23.7% of these cases. To replace intravenous insulin, a two-injection dosing regimen (in the morning and before dinner) was prescribed in 76.5% of cases, multi-injections of basal-bolus in 16%, and subcutaneous insulin infusion (insulin pump therapy) in 7.5% of cases. Between 2000 and 2010, there was no increase in overall incidence. It is noteworthy that age at diagnosis tended to decrease, but this was not statistically significant. In conclusion, the PEDIAB-LR registry is currently the only French registry on diabetes in children, analyzing many factors related to its incidence, such as age at diagnosis and the existence of ketoacidosis.

Environmental determinants of type 1 diabetes: a role for overweight and insulin resistance

Rates of type 1 diabetes are rising globally, with a decreasing proportion of high-risk genotypes and twin concordance rates below 50%. Therefore, environmental factors such as viruses, nutrition and overweight have been examined as putative aetiological agents. The accelerator hypothesis proposes that overweight and insulin resistance are central to both type 1 and type 2 diabetes and may explain, in part, the rise in type 1 diabetes incidence. The temporal rise in body mass index at type 1 diabetes onset and the observation that pre-diabetic children are heavier and more insulin resistant than their peers suggests convergence of type 1 and type 2 diabetes phenotypes. The influence of insulin resistance may begin in utero, although the aetiological role of birthweight in type 1 diabetes remains unclear. Further research to elucidate the role of these modifiable risk factors in today's obesogenic environment may provide future potential for diabetes prevention.

Infant exposures and development of type 1 diabetes mellitus: The Diabetes Autoimmunity Study in the Young (DAISY)

IMPORTANCE

The incidence of type 1 diabetes mellitus (T1DM) is increasing worldwide, with the most rapid increase among children younger than 5 years of age.

OBJECTIVE

To examine the associations between perinatal and infant exposures, especially early infant diet, and the development of T1DM.

DESIGN

The Diabetes Autoimmunity Study in the Young (DAISY) is a longitudinal, observational study.

SETTING

Newborn screening for human leukocyte antigen (HLA) was done at St. Joseph's Hospital in Denver, Colorado. First-degree relatives of individuals with T1DM were recruited from the Denver metropolitan area.

PARTICIPANTS

A total of 1835 children at increased genetic risk for T1DM followed up from birth with complete prospective assessment of infant diet. Fifty-three children developed T1DM.

EXPOSURES

Early (<4 months of age) and late (≥6 months of age) first exposure to solid foods compared with first exposures at 4 to 5 months of age (referent).

MAIN OUTCOME AND MEASURE

Risk for T1DM diagnosed by a physician.

RESULTS

Both early and late first exposure to any solid food predicted development of T1DM (hazard ratio [HR], 1.91; 95% CI, 1.04-3.51, and HR, 3.02; 95% CI, 1.26-7.24, respectively), adjusting for the HLA-DR genotype, first-degree relative with T1DM, maternal education, and delivery type. Specifically, early exposure to fruit and late exposure to rice/oat predicted T1DM (HR, 2.23; 95% CI, 1.14-4.39, and HR, 2.88; 95% CI, 1.36-6.11, respectively), while breastfeeding at the time of introduction to wheat/barley conferred protection (HR, 0.47; 95% CI, 0.26-0.86). Complicated vaginal delivery was also a predictor of T1DM (HR, 1.93; 95% CI, 1.03-3.61).

CONCLUSIONS AND RELEVANCE

These results suggest the safest age to introduce solid foods in children at increased genetic risk for T1DM is between 4 and 5 months of age. Breastfeeding while introducing new foods may reduce T1DM risk.

Growth differences between North American and European children at risk for type 1 diabetes

AIM

To evaluate the relationships between early growth and regional variations in type 1 diabetes (T1D) incidence in an international cohort of children with familial and genetic risk for T1D.

METHODS

Anthropometric indices between birth to 5 yr of age were compared among regions and T1D proband in 2160 children participating in the Trial to Reduce Insulin-dependent diabetes mellitus in the Genetically at Risk study.

RESULTS

Children in Northern Europe had the highest weight z-score between birth to 12 months of age, while those in Southern Europe and U.S.A. had the lowest weight and length/height z-scores at most time points (p < 0.005 to p < 0.001). Few differences in z-score values for weight, height, and body mass index were found by maternal T1D status. Using International Obesity Task Force criteria, the obesity rates generally increased with age and at 5 yr were highest in males in Northern Europe (6.0%) and in females in Canada (12.8%). However, no statistically significance difference was found by geographic region. In Canada, the obesity rate for female children of mothers with and without T1D differed significantly at 4 and 5 yr (6.0 vs. 0.0% and 21.3 vs. 1.9%, respectively; p < 0.0125) but no differences by maternal T1D status were found in other regions.

CONCLUSIONS

There are regional differences in early childhood growth that are consistent with the higher incidence of T1D in Northern Europe and Canada as compared to Southern Europe. Our prospective study from birth will allow evaluation of relationships between growth and the emerging development of autoimmunity and progression to T1D by region in this at-risk population of children.

Country-specific birth weight and length in type 1 diabetes high-risk HLA genotypes in combination with prenatal characteristics

OBJECTIVE

To examine the relationship between high-risk human leukocyte antigen (HLA) genotypes for type 1 diabetes and birth size in combination with prenatal ch aracteristics in different countries.

STUDY DESIGN

Four high-risk HLA genotypes were enrolled in the Environmental determinants of Diabetes in the Young study newborn babies from the general population in Finland, Germany, Sweden and the United States. Stepwise regression analyses were used to adjust for country, parental physical characteristics and environmental factors during pregnancy.

RESULT

Regression analyses did not reveal differences in birth size between the four type 1 diabetes high-risk HLA genotypes. Compared with DQ 4/8 in each country, (1) DQ 2/2 children were heavier in the United States (P=0.028) mostly explained however, by parental weight; (2) DQ 2/8 (P=0.023) and DQ 8/8 (P=0.046) children were longer in Sweden independent of parents height and as well as (3) in the United States for DQ 2/8 (P=0.023), but again dependent on parental height.

CONCLUSION

Children born with type 1 diabetes high-risk HLA genotypes have comparable birth size. Longitudinal follow-up of these children should reveal whether birth size differences between countries contribute to the risk for islet autoimmunity and type 1 diabetes.

Type 1 diabetes and perinatal factors in Catalonia (Spain)

AIM

To identify perinatal risk factors associated with the development of type 1 diabetes.

METHODS

The research was designed as a retrospective study of cases and controls. Catalan Register of Diabetes and the Register of Newborn Screening for Metabolic Diseases were the data sources used in this study. The variables studied include sex, birth weight, age of onset of type 1 diabetes, maternal age at delivery, type of delivery, and type of feeding at birth. Anthropometric growth patterns of Carrascosa have been used to classify birth weight as small for gestational age: weight <10th percentile; appropriate for gestational age: weight ≥10th percentile and ≤90th percentile; and large for gestational age (LGA): weight >90th percentile. Statistical analysis was carried out using bivariate analysis (chi-squared test), and odds ratios and 95% confidence intervals were predicted.

RESULTS

A total of 1530 infants were analyzed (306 type 1 diabetes cases, 1224 control subjects). A significantly greater percentage of LGA babies were observed among diabetics (16.3% compared with 11.3% of the control group). The risk of having type 1 diabetes in children who were LGA was 1.45 times greater than that shown in children with normal and low birth weight.

CONCLUSIONS

Only being born LGA was significantly associated with developing type 1 diabetes.

Maternal and neonatal risk factors for childhood type 1 diabetes: a matched case-control study

Background

An interaction between genetic susceptibility and environmental factors is thought to be involved in the aetiology of type 1 diabetes. The aim of this study was to investigate maternal and neonatal risk factors for type 1 diabetes in children under 15 years old in Grampian, Scotland.

Methods

A matched case-control study was conducted by record linkage. Cases (n = 361) were children born in Aberdeen Maternity Hospital from 1972 to 2002, inclusive, who developed type 1 diabetes, identified from the Scottish Study Group for the Care of Diabetes in the Young Register. Controls (n = 1083) were randomly selected from the Aberdeen Maternity Neonatal Databank, matched by year of birth. Exposure data were obtained from the Aberdeen Maternity Neonatal Databank. Conditional logistic regression was used to evaluate the association between various maternal and neonatal factors and the risk of type 1 diabetes.

Results

There was no evidence of statistically significant associations between type 1 diabetes and maternal age, maternal body mass index, previous abortions, pre-eclampsia, amniocentesis, maternal deprivation, use of syntocinon, mode of delivery, antepartum haemorrhage, baby's sex, gestational age at birth, birth order, birth weight, jaundice, phototherapy, breast feeding, admission to neonatal unit and Apgar score (P > 0.05). A significantly decreased risk of type 1 diabetes was observed in children whose mothers smoked at the booking appointment compared to those whose mothers did not, with an adjusted OR of 0.67, 95% CI (0.46, 0.99).

Conclusions

This case-control study found limited evidence of a reduced risk of the development of type 1 diabetes in children whose mothers smoked, compared to children whose mothers did not. No evidence was found of a significant association between other maternal and neonatal factors and childhood type 1 diabetes.

Revisiting infant growth prior to childhood onset type 1 diabetes

OBJECTIVE

Accelerated early growth prior to childhood type 1 diabetes onset is associated with an increased risk for type 1 diabetes (T1D). We aimed to study early growth, correcting for the previously neglected confounder of familial effects.

DESIGN

Infant growth was studied in a retrospective family case-control study of diabetic children in which siblings acted as matched familial controls allowing correction for confounders related to family particulars.

PATIENTS

Weight and height data were collected from 213 juvenile onset type 1 diabetic children and their 255 healthy siblings. Growth in the first 4 years of life was studied using repeated measurement. The degree of early overgrowth was correlated with age of clinical onset.

RESULTS

Birth weight and length did not differ between later diabetic children and their siblings. In the first year of life, weight standard deviation score (SDS) differed between patients and sibs (P = 0.0001). After the first year, both diabetic children and sibs showed parallel enhanced weight and height gain SDS until age 4 years. Earlier onset diabetes was associated with a higher weight SDS at 6 months of age.

CONCLUSION

In this family case-control study the association of increased growth with development of T1D is limited to the first year of life implying that increased growth beyond the first year can be attributed to familial growth patterns, rather than predisposition to T1D per se. Age at disease onset correlated with increased weight in the first 6 months of life, indicating importance of features very early in life on later development of T1D.

Birthweight and the risk of childhood-onset type 1 diabetes: a meta-analysis of observational studies using individual patient data

AIMS/HYPOTHESIS

We investigated whether children who are heavier at birth have an increased risk of type 1 diabetes.

METHODS

Relevant studies published before February 2009 were identified from literature searches using MEDLINE, Web of Science and EMBASE. Authors of all studies containing relevant data were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of birthweight were calculated for each study, before and after adjustment for potential confounders.Meta-analysis techniques were then used to derive combined ORs and investigate heterogeneity between studies.

RESULTS

Data were available for 29 predominantly European studies (five cohort, 24 case-control studies), including 12,807 cases of type 1 diabetes. Overall, studies consistently demonstrated that children with birthweight from 3.5 to 4 kg had an increased risk of diabetes of 6% (OR 1.06 [95% CI 1.01-1.11]; p=0.02) and children with birthweight over 4 kg had an increased risk of 10% (OR 1.10 [95% CI 1.04-1.19]; p=0.003), compared with children weighing 3.0 to 3.5 kg at birth. This corresponded to a linear increase in diabetes risk of 3% per 500 g increase in birthweight (OR 1.03 [95% CI 1.00-1.06]; p=0.03). Adjustments for potential confounders such as gestational age, maternal age, birth order, Caesarean section, breastfeeding and maternal diabetes had little effect on these findings.

CONCLUSIONS/INTERPRETATION

Children who are heavier at birth have a significant and consistent, but relatively small increase in risk of type 1 diabetes.

Age at onset of type 1 diabetes in parents and recurrence risk in offspring

OBJECTIVE

Our aim was to study the recurrence risk of type 1 diabetes in the offspring of parents with adult-onset (15-39 years) type 1 diabetes and to evaluate the transmission of diabetes within a continuum of parental age at onset of diabetes from childhood to adulthood.

RESEARCH DESIGN AND METHODS

Diabetes status of all offspring (n = 9,636) in two Finnish cohorts of parents with type 1 diabetes was defined until the end of year 2007. Cumulative incidences of type 1 diabetes among the offspring were estimated, and several factors contributing to the risk were assessed.

RESULTS

During 137,455 person-years, a total of 413 offspring were diagnosed with type 1 diabetes. The cumulative incidence by 20 years was 4.0% (95% CI 3.1-4.8) for the offspring of parents with adult-onset diabetes. The risk was equal according to the sex of the parents. The cumulative incidence decreased in parallel with the increase in age at onset of diabetes in the fathers. In the offspring of diabetic mothers, the risk was equal regardless of the age at onset of diabetes. However, the reduced risk in the maternal offspring was most pronounced in the daughters of the mothers with a diagnosis age <10 years.

CONCLUSIONS

Type 1 diabetes transmission ratio distortion is strongly related to the sex and age at onset of diabetes in the diabetic parents.

Weight and length at birth and their relationship to diabetes incidence and all-cause mortality--a 32-year follow-up of the population study of women in Gothenburg, Sweden

OBJECTIVE

The purpose of the study was to explore the relationship of weight and length at birth to diabetes in adult life and to all-cause mortality. Special attention was taken to potential confounding factors as age, family history, education, socio-economic group, physical inactivity, smoking, blood pressure, serum lipids and obesity.

RESEARCH DESIGN AND METHODS

A longitudinal population study consisting of a representative sample of 1381 women aged 38-54 started in Gothenburg, Sweden, in 1968-1969 monitoring for diabetes mellitus and overall mortality over 32 years. Original delivery records were retrieved for 61.2% of the women. Death certificates were obtained for 99.3% the women who died during the 32-year follow-up period.

RESULTS

We observed an inverse statistically significant relationship between birth weight and 32-year diabetes incidence independent of age, the highest incidence 16.3% in the lowest quartile of birth weight compared to 9.2% in the highest quartile. The relationship remained when controlling for the following covariates: education, socio-economic group, physical activity, smoking, systolic blood pressure, adult body mass index (BMI), waist-hip ratio, serum triglycerides and cholesterol. When overweight women (BMI> or =25) were excluded from the statistical analyses birth weight was even stronger related to the incidence of diabetes, 12.8% in lowest quartile and 5.7% in the highest quartile of birth weight independent of birth length, education, socio-economic group, physical activity, smoking, systolic blood pressure, body mass index, waist-hip ratio, blood glucose, serum triglycerides and cholesterol. Length at birth was a predictor for diabetes independent of age plus adult body mass index (BMI) and smoking but not independent of age only. No significant associations were observed between birth factors as birth weight and birth length and overall mortality during the 32-year of follow-up.

CONCLUSIONS

A low birth weight seems to be a risk factor for diabetes in adult women independent of age and most of the established risk factors for diabetes.

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

AIMS/HYPOTHESIS

High birthweight and increased childhood growth are risk factors for type 1 diabetes. Relative birthweight is associated with HLA genotypes that confer a high risk of diabetes. Our aims were to test whether young children prior to clinical onset of type 1 diabetes have increased: (1) birthweight or birth length standard deviation scores (SDS); (2) height development SDS; or (3) BMI SDS during first 18 months of life and whether these parameters are related to HLA genotypes or mid-parental height (MPH).

METHODS

Birthweight, birth length, weight and height were obtained from 58 type 1 diabetes children and 155 controls matched for HLA or not in the Diabetes Prediction in Skåne study.

RESULTS

Birth length SDS corrected for MPH was increased in children developing diabetes compared with all (p < 0.048) and with non-HLA- (p < 0.050) but not with HLA-matched controls. Children developing diabetes had increased height gain at 0 to 18 months of age (p < 0.005). Diabetic children were significantly taller from 6 to 18 months of age when correcting for MPH compared with non-HLA-matched as well as HLA-matched controls, but BMI was not increased.

CONCLUSIONS/INTERPRETATION

Birth length SDS was associated with diabetes risk HLA. When corrected for MPH, children developing diabetes were taller at birth than non-HLA- but not taller than HLA-matched controls. Diabetic children had increased MPH-corrected height up to 18 months of age compared with both HLA- and non-HLA-matched controls. High-risk HLA affects prenatal growth, but other factors may explain the increased postnatal linear growth in children developing diabetes.

Perinatal risk factors for early childhood onset type 1 diabetes in Austria - a population-based study (1989-2005)

BACKGROUND

To investigate the rapid increase in incidence of type 1 diabetes mellitus (T1DM) in children <5 yr in Austria.

METHODS

Data of children born between 1989 and 2005 (n = 444) from the T1DM children incidence registry were linked with birth certificates (n = 1 407 829).

RESULTS

Age of mother, level of education, birth weight, birth length, body mass index, and APGAR score at 10 min were not significant. Boys have about 25% higher risk than girls [hazard ratio = 0.75, 95% confidence interval (CI): 0.62-0.91]. The risk of developing diabetes increases over time significantly (1989-1991 vs. 2001-2005, hazard ratio = 2.86, 95% CI: 2.07-3.94). The linear effect of parity is borderline significant (p = 0.045), with lower risks for second and later born siblings. Marital status is significant [hazard ratio = 0.73, 95% CI: 0.57-0.90)]. Native-born children exhibit twice as high risk as non-native children (hazard ratio = 0.51, 95% CI: 0.37-0.71). Birth weight shows a positive but not significant effect on risk of T1DM.

CONCLUSIONS

In this very young and rapidly increasing cohort of diabetic children <5 yr of age, no association with birth weight but with year of birth, gestational age, nationality and parity could be observed.

Parental country of birth is a major determinant of childhood type 1 diabetes in Sweden

OBJECTIVE

To test the hypothesis that the risk of childhood diabetes type 1 increases with migration from a low to a high incidence region.

METHODS

Register study of a national cohort of 783 547 children born between 1987 and 1993 who remained in Sweden in 2002, including 3225 children with childhood type 1 diabetes identified in hospital discharge data. Logistic regression analysis was used to test the hypotheses.

RESULTS

Offspring of two parents born in very low (Asia excluding Middle East and Latin America) and low (southern and eastern Europe and the Middle East) incidence regions had the lowest adjusted odds ratios (ORs) of childhood type 1 diabetes; 0.21 (0.11-0.41) and 0.37 (0.29-0.48), respectively, compared with the Swedish majority population. When one parent was born in a low incidence country and one parent was Swedish born, the adjusted ORs increased but remained lower than the Swedish majority population.

CONCLUSIONS

Parental country of birth is an important determinant of childhood type 1 in Sweden. Heritable factors seem most likely to explain this pattern.

In utero undernutrition reduces diabetes incidence in non-obese diabetic mice

AIMS/HYPOTHESIS

Observational studies in humans suggest that low birthweight may decrease the risk of type 1 diabetes, but the mechanism is unknown. We hypothesised that antenatal undernutrition would decrease the incidence of type 1 diabetes in non-obese diabetic (NOD) mice.

MATERIALS AND METHODS

A 40% restriction of energy intake was applied to pregnant NOD dams from day 12.5 to day 18.5 of gestation, resulting in intrauterine growth retardation of offspring. All mice were fed a standard diet after weaning. Control and undernourished female offspring were followed to assess diabetes incidence. Male NOD mice were treated with cyclophosphamide to accelerate development of diabetes. Glucose homeostasis, body composition and pancreatic histology were compared in control and undernourished offspring.

RESULTS

Mean birthweight was lower in undernourished than in control mice (p = 0.00003). At 24 weeks of age, the cumulative incidence of spontaneous diabetes in female mice was 73% in control and 48% in undernourished mice (p = 0.003). In cyclophosphamide-treated male mice, antenatal undernutrition also tended to reduce the development of diabetes (p = 0.058). Maternal leptin levels were lower in undernourished dams on day 18.5 of pregnancy (p = 0.039), while postnatal leptin levels were significantly higher in undernourished offspring at 4, 20 and 27 weeks of life (p < 0.05). Beta cell mass was similar in both groups (control = 0.4 mg; undernourished = 0.54 mg; p = 0.24). Histological evidence of apoptosis at 20 weeks was greater in control than in undernourished mice (control = 6.3 +/- 1.4%; undernourished = 4.2 +/- 0.3%, p = 0.05).

CONCLUSIONS/INTERPRETATION

Antenatal undernutrition reduces the incidence of diabetes in NOD mice, perhaps via alterations in apoptosis.

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

AIMS/HYPOTHESIS

Intrauterine growth in non-diabetic pregnancies is reported to be influenced by type 1 diabetes susceptibility genes. In particular, the high-risk HLA DR4_DQB1*0302 haplotype is associated with increased birthweight. The aim of this study was to determine whether HLA DR4 was associated with increased birthweight in a maternal diabetes environment and whether effects persisted during early childhood.

SUBJECTS AND METHODS

Birthweight and gestational age were obtained in singleton births from mothers with type 1 diabetes (n = 1161) or whose fathers or siblings have type 1 diabetes (n = 872). Weight and height at ages 2 and 5 years were obtained from paediatric records. Data were adjusted for (gestational) age and sex and expressed as percentiles of German reference data. HLA DR typing was obtained for all children and 1090 children also had insulin gene (INS) variable number of tandem repeats (VNTR) typing.

RESULTS

Maternal type 1 diabetes was associated with increased birthweight, gestational age and birthweight percentiles (all p < 0.0001). In children of mothers with type 1 diabetes, birthweight percentile was further related to maternal HbA(1c) during pregnancy (r = 0.26; p < 0.0001) and was independently increased if children had HLA DR4 alleles (76th vs 64th percentile; p < 0.0001). HLA DR4 was not associated with birthweight in children of non-diabetic mothers. Birthweight was not associated with INS VNTR genotypes. High birthweight, but not HLA DR4 was associated with increased weight and BMI at ages 2 and 5 years (p < 0.0001).

CONCLUSIONS/INTERPRETATION

Our findings are consistent with the hypothesis that a diabetic intrauterine environment interacts with gene(s) marked by the type 1 diabetes susceptibility HLA DR4 alleles to increase fetal growth.

Patterns of growth among children who later develop type 2 diabetes or its risk factors

AIMS/HYPOTHESIS

We studied fetal and childhood growth patterns that are associated with IGT and type 2 diabetes in adult life.

METHODS

We examined clinically 2,003 subjects born in Helsinki between 1934 and 1944. They had on average 11 measurements of height and weight between birth and 2 years of age, and seven measurements between 2 and 11 years of age. Glucose tolerance in adult life was assessed by a 75-g oral glucose tolerance test.

RESULTS

We identified 311 subjects with type 2 diabetes and 496 with IGT. Both IGT and type 2 diabetes were associated with low birthweight (p < 0.0001 adjusting for current BMI). The risk of these conditions was increased by low weight gain between birth and 2 years. A 1 SD increase in weight at 2 years was associated with an odds ratio for either type 2 diabetes or IGT of 0.76 (95% CI 0.69-0.84). This effect was greatest in people who had low birthweight. Low growth in the first 6 months after birth was a critical period for the development of insulin resistance in later life; other critical periods were associated with slow fetal growth and rapid increase in BMI between age 2 and 11 years.

CONCLUSIONS/INTERPRETATION

Low weight gain during infancy increases the risk of IGT and type 2 diabetes. The effect is greater in people who had low birthweight. The first 6 months after birth may be the most critical period for growth, in relation to development of glucose intolerance.

Environmental factors in the development of Type 1 diabetes

Environmental factors appear to play an important role in the pathogenesis of childhood-onset type 1 diabetes (T1D). The most important factors are thought to be infectious, dietary, perinatal, and psychosocial. Enteroviruses (especially Coxsackie B virus), breastfeeding, the early presence or lack of certain foods, birth weight, childhood over-nutrition, maternal islet autoimmunity, and negative stress events have been shown to be related to the prevalence of T1D. However, clear conclusions to date are limited because most studies lacked power to detect exposure/disease associations, were not prospective or long-term, did not start in infancy, had imprecise or infrequent exposure estimates, had confounding exposures, and failed to account for genetic susceptibility. In addition to the identification of specific antigenic triggers, several more general hypotheses, including the accelerator and hygiene hypotheses, are testable approaches worth pursuing.

The relation between size at birth and risk of type 1 diabetes is not influenced by adjustment for the insulin gene (-23HphI) polymorphism or HLA-DQ genotype

AIMS/HYPOTHESIS

Associations have been described between higher birthweight and increased risk of type 1 diabetes, and of insulin (INS) and human leucocyte antigen (HLA) genotypes that protect against diabetes with larger size at birth. We studied simultaneously the effects of size at birth, INS and HLA genotypes on the risk of type 1 diabetes to test whether the relation between size at birth and risk of type 1 diabetes would be strengthened after adjustment for INS and HLA genotypes.

SUBJECTS AND METHODS

We designed a population-based case-control study in Norway with 471 cases of childhood-onset type 1 diabetes and 1,369 control subjects who were genotyped for the INS -23HphI polymorphism (surrogate for INS variable number of tandem repeats) and HLA-DQ alleles associated with type 1 diabetes. Data on birthweight and other perinatal factors were obtained from the Medical Birth Registry of Norway by record linkage.

RESULTS

The data fitted a multiplicative model for the protective INS class III allele both within the INS locus and for the model with INS- and HLA-DQ-conferred risk of type 1 diabetes. We found no overall significant association between weight or head circumference at birth and the risk of type 1 diabetes, and adjustment for INS and HLA genotype did not influence this result. There was also no evidence for association of INS or HLA with size at birth among control subjects.

CONCLUSIONS/INTERPRETATION

In contrast to suggestions from previous indirect studies, direct adjustment for INS and HLA genotypes did not lead to a stronger relation between birthweight and the risk of type 1 diabetes.