A high linear growth is associated with an increased risk of childhood diabetes mellitus

Changes in the Global Epidemiology of Type 1 Diabetes in an Evolving Landscape of Environmental Factors: Causes, Challenges, and Opportunities

The worldwide incidence of type 1 diabetes mellitus (T1DM) has increased in recent decades. The reasons behind this phenomenon are not yet fully understood. Early life infections, prenatal and perinatal factors, and diet composition have been associated with the triggering of autoimmunity and the risk of presentation of T1DM. However, the rapid increase in new cases of the disease raises the hypothesis that lifestyle factors, which have traditionally been associated with type 2 diabetes, such as obesity and unhealthy eating patterns could also play a role in the genesis of autoimmune diabetes. This article aims to highlight the changing epidemiology of T1DM and the importance of properly recognizing the environmental factors behind it, as well as the connections with the pathogenesis of the disorder and the need to prevent or delay T1DM and its long-term complications.

The incidence of childhood-onset type 1 diabetes, time trends and association with the population composition in Sweden: a 40 year follow-up

AIMS/HYPOTHESIS

During the 1980s and 1990s, the incidence of childhood-onset type 1 diabetes more than doubled in Sweden, followed by a plateau. In the present 40 year follow-up, we investigated if the incidence remained stable and whether this could be explained by increased migration from countries reporting lower incidences.

METHODS

We used 23,143 incident cases of childhood-onset type 1 diabetes reported between 1978 and 2019 to the nationwide, population-based Swedish Childhood Diabetes Registry and population data from Statistics Sweden. Generalised additive models and ANOVA were applied to analyse the effects of onset age, sex, time trends and parental country of birth and interaction effects between these factors.

RESULTS

The flattening of the incidence increase seems to remain over the period 2005-2019. When comparing the incidence of type 1 diabetes for all children in Sweden with that for children with both parents born in Sweden, the trends were parallel but at a higher level for the latter. A comparison of the incidence trends between individuals with Swedish backgrounds (high diabetes trait) and Asian backgrounds (low diabetes trait) showed that the Asian subpopulation had a stable increase in incidence over time.

CONCLUSIONS/INTERPRETATION

In Sweden, the increase in incidence of childhood-onset type 1 diabetes in the late 20th century has been approaching a more stable albeit high level over the last two decades. Increased immigration from countries with lower incidences of childhood-onset type 1 diabetes does not provide a complete explanation for the observed levelling off.

Obesity in late adolescence and incident type 1 diabetes in young adulthood

AIMS/HYPOTHESIS

Studies in children have reported an association between increased BMI and risk for developing type 1 diabetes, but evidence in late adolescence is limited. We studied the association between BMI in late adolescence and incident type 1 diabetes in young adulthood.

METHODS

All Israeli adolescents, ages 16-19 years, undergoing medical evaluation in preparation for mandatory military conscription between January 1996 and December 2016 were included for analysis unless they had a history of dysglycaemia. Data were linked with information about adult onset of type 1 diabetes in the Israeli National Diabetes Registry. Weight and height were measured at study entry. Cox proportional models were applied, with BMI being analysed both as a categorical and as a continuous variable.

RESULTS

There were 777 incident cases of type 1 diabetes during 15,819,750 person-years (mean age at diagnosis 25.2±3.9 years). BMI was associated with incident type 1 diabetes. In a multivariable model adjusted for age, sex and sociodemographic variables, the HRs for type 1 diabetes were 1.05 (95% CI 0.87, 1.27) for the 50th-74th BMI percentiles, 1.41 (95% CI 1.11, 1.78) for the 75th-84th BMI percentiles, 1.54 (95% CI 1.23, 1.94) for adolescents who were overweight (85th-94th percentiles), and 2.05 (95% CI 1.58, 2.66) for adolescents with obesity (≥95th percentile) (reference group: 5th-49th BMI percentiles). One increment in BMI SD was associated with a 25% greater risk for incidence of type 1 diabetes (HR 1.25, 95% CI 1.17, 1.32).

CONCLUSIONS

Excessively high BMI in otherwise healthy adolescents is associated with increased risk for incident type 1 diabetes in early adulthood.

Childhood Height Growth Rate Association With the Risk of Islet Autoimmunity and Development of Type 1 Diabetes

CONTEXT

Rapid growth has been suggested to promote islet autoimmunity and progression to type 1 diabetes (T1D). Childhood growth has not been analyzed separately from the infant growth period in most previous studies, but it may have distinct features due to differences between the stages of development.

OBJECTIVE

We aimed to analyze the association of childhood growth with development of islet autoimmunity and progression to T1D diagnosis in children 1 to 8 years of age.

METHODS

Longitudinal data of childhood growth and development of islet autoimmunity and T1D were analyzed in a prospective cohort study including 10 145 children from Finland, Germany, Sweden, and the United States, 1-8 years of age with at least 3 height and weight measurements and at least 1 measurement of islet autoantibodies. The primary outcome was the appearance of islet autoimmunity and progression from islet autoimmunity to T1D.

RESULTS

Rapid increase in height (cm/year) was associated with increased risk of seroconversion to glutamic acid decarboxylase autoantibody, insulin autoantibody, or insulinoma-like antigen-2 autoantibody (hazard ratio [HR] = 1.26 [95% CI = 1.05, 1.51] for 1-3 years of age and HR = 1.48 [95% CI = 1.28, 1.73] for >3 years of age). Furthermore, height rate was positively associated with development of T1D (HR = 1.80 [95% CI = 1.15, 2.81]) in the analyses from seroconversion with insulin autoantibody to diabetes.

CONCLUSION

Rapid height growth rate in childhood is associated with increased risk of islet autoimmunity and progression to T1D. Further work is needed to investigate the biological mechanism that may explain this association.

Incidence of type 1 diabetes among children and adolescents during peace and war times in Yemen

AIM

To calculate a 30-year incidence rates of type 1 diabetes (T1D) in Sana'a city, Yemen during peace and wartimes.

METHODS

A total of 461 patients aged between 8 months and 18 years with newly diagnosed diabetes were registered between 1989 and 2018. We used a standardized protocol for counting cases over time. The annual incidence rates (cases/100,000/year) were calculated from the number of new reported cases for each year divided by the estimated number of person-years "at risk" resident in Sana'a city, Yemen according to age and sex of the participants of that year.

RESULTS

The mean annual incidence rate of T1D in children aged 0-14 years was 1.83/100,000/year. With the use of 3-year time-periods, the mean annual incidence rate was (5/100,000/year) in the first time-period, fluctuated between 1.2 and 2.3 during subsequent seven time-periods, and declined to (0.5/100,000/year) during the conflict years. The age-specific mean annual incidence rates for age-groups 0-4, 5-9, 10-14, and 15-18 years were 0.83, 1.82, 3.14, and 2.31/100,000/year, respectively.

CONCLUSION

The mean annual incidence rate of T1D in children and adolescents over the observation period in Sana'a city was low. In children aged 0-14 years in particular, the incidence declined to a very low rate during wartime. Interpretation is partly limited by lack of recent census data, and the possibility of death from nondiagnosis at onset.

The High-Risk Type 1 Diabetes HLA-DR and HLA-DQ Polymorphisms Are Differentially Associated With Growth and IGF-I Levels in Infancy: The Cambridge Baby Growth Study

OBJECTIVE

This study explored the link between HLA polymorphisms that predispose to type 1 diabetes and birth size, infancy growth, and/or circulating IGF-I in a general population-based birth cohort.

RESEARCH DESIGN AND METHODS

The Cambridge Baby Growth Study is a prospective observational birth cohort study that recruited 2,229 newborns for follow-up in infancy. Of these, 612 children had DNA available for genotyping single nucleotide polymorphisms in the HLA region that capture the highest risk of type 1 diabetes: rs17426593 for DR4, rs2187668 for DR3, and rs7454108 for DQ8. Multivariate linear regression models at critical ages (cross-sectional) and mixed-effects models (longitudinal) were performed under additive genetic effects to test for associations between HLA polymorphisms and infancy weight, length, skinfold thickness (indicator of adiposity), and concentrations of IGF-I and IGF-binding protein-3 (IGFBP-3).

RESULTS

In longitudinal models, the minor allele of rs2187668 tagging DR3 was associated with faster linear growth (P = 0.007), which was more pronounced in boys (P = 3 × 10^-7) than girls (P = 0.07), and was also associated with increasing IGF-I (P = 0.002) and IGFBP-3 (P = 0.003) concentrations in infancy. Cross-sectionally, the minor alleles of rs7454108 tagging DQ8 and rs17426593 tagging DR4 were associated with lower IGF-I concentrations at age 12 months (P = 0.003) and greater skinfold thickness at age 24 months (P = 0.003), respectively.

CONCLUSIONS

The variable associations of DR4, DR3, and DQ8 alleles with growth measures and IGF-I levels in infants from the general population could explain the heterogeneous growth trajectories observed in genetically at-risk cohorts. These findings could suggest distinct mechanisms involving endocrine pathways related to the HLA-conferred type 1 diabetes risk.

Perinatal factors and the risk of type 1 diabetes in childhood and adolescence-A register-based case-cohort study in Finland, years 1987 to 2009

OBJECTIVES

Our aim was to clarify previously reported associations and to explore new ones between various maternal background and perinatal factors and the risk of type 1 diabetes in childhood.

METHODS

We identified all children born 1 January 1987 to 31 December 2008 in Finland and diagnosed with type 1 diabetes by age 16 years or end of 2009 from the Special Reimbursement Register (n = 6862). A 10% random sample from each birth year cohort was selected as a reference cohort (n = 127 216). Information on perinatal factors was obtained from the Finnish Medical Birth Register.

RESULTS

Maternal diabetes (hazard ratios [HR] = 6.43; 95% confidence interval [CI] 5.35, 7.73), maternal asthma (HR = 1.23; 95% CI 1.06, 1.43), child's high birth length for gestational age (HR = 1.35; 95% CI 1.22, 1.51 highest vs lowest quintile) and premature or early term birth (HR = 1.21; 95% CI 1.05, 1.39 gestational weeks 33-36 and HR = 1.17; 95% CI 1.09, 1.26 gestational weeks 37-38 vs gestational weeks 39-40) was associated with an increased risk of type 1 diabetes when adjusted for several potential confounders. Maternal smoking during pregnancy (HR = 0.72; 95% CI 0.66, 0.77), high number of previous live births (HR = 0.65; 95% CI 0.55, 0.76 ≥ 4 vs 0 live births), and the child being born small for gestational age (HR = 0.80; 95% CI 0.67, 0.96) was associated with a decreased risk of type 1 diabetes.

CONCLUSIONS

Findings on maternal asthma and high birth length for gestational age increasing the risk of type 1 diabetes are novel and need to be confirmed. Our findings indicate that perinatal factors may play a role in the development of type 1 diabetes.

Could the high consumption of high glycaemic index carbohydrates and sugars, associated with the nutritional transition to the Western type of diet, be the common cause of the obesity epidemic and the worldwide increasing incidences of Type 1 and Type 2 diabetes?

The globally increasing incidences of Type 1 diabetes (T1DM) and Type 2 diabetes (T2DM) can have a common background. If challenged by the contemporary high level of nutritional glucose stimulation, the β-cells in genetically predisposed individuals are at risk for damage which can lead to the diseases. The fat to carbohydrate dietary shift can also contribute to the associated obesity epidemic.

Standard body mass index reference data of prepubescent diabetic Egyptian children

BACKGROUND

Data on the growth of diabetic children is conflicting. The aim of this study was to create and validate acceptable body mass index (BMI)-standardized percentiles and curves applied to Egyptian prepubescent diabetic children.

METHODS

The cross-sectional study comprised 822 prepubescent children with type 1 diabetes mellitus (T1DM), whose ages ranged from 3 years to 10 years±6 months. An anthropometric assessment for each child was performed: body weight, height and BMI were calculated (weight [kg]/height [m2]), and glycated hemoglobin levels were determined. Means±standard deviations (SDs) and the smoothed percentiles of the BMI from age 3-10 years, by sex, for total, controlled and uncontrolled diabetic children were calculated. Comparisons of the 50th percentiles for the controlled and uncontrolled diabetic children, by sex, with those of the Egyptian and World Health Organization (WHO) growth curves were made.

RESULTS

For controlled diabetic males and females, the 50th percentile BMI was higher than those of the Egyptian and WHO growth curves, while differences in BMI were recorded for uncontrolled diabetic males and females. For uncontrolled diabetic males, the BMI was lower than the standard Egyptian and WHO growth curves up to 5 years of age, after which it became higher than the standard WHO and lower than the standard Egyptian growth curves from 5 years up to 10 years of age. Contrary to that, the BMI of uncontrolled diabetic females was higher than the standard Egyptian and WHO growth curves up to 6.5 years, between the curves from 6.5 years up to 7.5 years and then became lower than both curves up to 10 years of age.

CONCLUSIONS

Children with T1DM should use their own BMI percentiles and never be compared with normal healthy children.

Growth in patients with type 1 diabetes

PURPOSE OF REVIEW

As the incidence of type 1 diabetes (T1DM) continues to rise, complications including impairment of childhood growth remain a major concern. This review provides an overview of alterations in growth patterns before and after the onset of T1DM.

RECENT FINDINGS

Recent advances in this field include several prospective investigations of height and weight trajectories in children leading up to the development of islet autoimmunity and T1DM as well as evaluations of larger cohorts of T1DM patients to better assess predictors of altered growth. In addition, genetic and metabolic investigations have improved our understanding of the more rare severe growth impairment of Mauriac Syndrome.

SUMMARY

Despite advances in medical care of children with T1DM, growth remains suboptimal in this population and likely reflects ongoing metabolic derangement linked with classic microvascular diabetic complications.

Growth and Risk for Islet Autoimmunity and Progression to Type 1 Diabetes in Early Childhood: The Environmental Determinants of Diabetes in the Young Study

Increased growth in early childhood has been suggested to increase the risk of type 1 diabetes. This study explored the relationship between weight or height and development of persistent islet autoimmunity and progression to type 1 diabetes during the first 4 years of life in 7,468 children at genetic risk for type 1 diabetes followed in Finland, Germany, Sweden, and the U.S. Growth data collected every third month were used to estimate individual growth curves by mixed models. Cox proportional hazards models were used to evaluate body size and risk of islet autoimmunity and type 1 diabetes. In the overall cohort, development of islet autoimmunity (n = 575) was related to weight z scores at 12 months (hazard ratio [HR] 1.16 per 1.14 kg in males or per 1.02 kg in females, 95% CI 1.06-1.27, P < 0.001, false discovery rate [FDR] = 0.008) but not at 24 or 36 months. A similar relationship was seen between weight z scores and development of multiple islet autoantibodies (1 year: HR 1.21, 95% CI 1.08-1.35, P = 0.001, FDR = 0.008; 2 years: HR 1.18, 95% CI 1.06-1.32, P = 0.004, FDR = 0.02). No association was found between weight or height and type 1 diabetes (n = 169). In conclusion, greater weight in the first years of life was associated with an increased risk of islet autoimmunity.

Growth attainments of Indian children with type 1 diabetes: a mixed longitudinal study

OBJECTIVE

To evaluate distance and velocity growth of children with Type 1 Diabetes (T1D) and quantify the magnitude of gender differences in anthropometric parameters.

METHODS

Children with T1D, without any coexisting condition that could affect growth were measured at half yearly intervals for body weight, height, occipito-frontal circumference (OFC), chest circumference (CC), mid upper arm circumference (MUAC), triceps skinfold thickness (TSFT), biceps skinfold thickness (BSFT) and subscapular skinfold thickness (SSSFT) using standardized techniques. Comparison of these growth parameters was made between the 2 genders as well as with the published norms.

RESULTS

Of the 115 children studied, there were no significant gender differences in weight at different age points. Boys measured taller than girls but the gender differences in height were significant only at 7 and 10 y. There was a tendency of higher BMIs in girls. In comparison to WHO standards and normal Indian children, boys had lower weight initially but became heavier later. The girls showed close similarity to their normal Indian counterparts but remained lighter than their WHO counterparts. After the initial lower height, an acceleratory trend was noted in boys but girls remained shorter throughout the study as compared to WHO peers. Boys, in general had higher CC, OFC, MUAC and MUAMC. The skinfold thicknesses recorded inconsistent growth patterns in both sexes. Growth velocities for various body parameters except skinfold thicknesses were similar in boys and girls.

CONCLUSIONS

Initial weight and height loss followed by catch up growth was noted in boys. The values of MUAC, MUAMC and skinfold thicknesses as compared to data from developed countries, were lower in present patients.

Physical Growth and Body Composition of Controlled Versus Uncontrolled Type 1 Egyptian Diabetic Children

BACKGROUND: Type 1 Diabetes Mellitus (T1DM) is one of the most common chronic endocrine disorders of childhood. Data on growth parameters of diabetic children is scarce.AIM: To assess growth and body composition in a group of diabetic children.SUBJECTS AND METHODS: 427 T1DM children (age 2-10 years) were recruited from Diabetic Paediatric Unit, outpatients' clinic of Abou El-Rish Hospital. Anthropometric and body composition parameters were taken and HbA1c was measured for all subjects.RESULTS:  Highly significant difference was detected between controlled and uncontrolled groups as regard to weight/age z-score, height/age z-score, BMI z-score, triceps skin fold thickness, subscapular skin fold thickness, midupper arm circumference, fat mass, fat %, lean mass, and body water (p < 0.001). All values are higher in the controlled group than in the uncontrolled group. Uncontrolled subjects were significantly more at risk of being underweight and short, with odds ratio of 15.131 and 16.877 and 95% confidence interval 1.972-116.130 and 3.973-71.694 respectively. However, controlled subjects were significantly more at risk of being obese than the uncontrolled with an odds ratio 0.116 and 95% confidence interval 0.045-0.302.CONCLUSION: Growth was compromised in uncontrolled T1DM children. This is of utmost importance since most of the clinical features are reversible with better glycemic control and appropriate insulin management.

Early infant growth is associated with the risk of islet autoimmunity in genetically susceptible children

BACKGROUND

Islet autoimmunity commonly develops early in infancy. We assessed whether specific parameters of early growth (including weight gain) were associated with the development of islet autoimmunity in children of type 1 diabetes patients, taking individual developmental patterns into account.

METHODS

Growth parameters were estimated in n = 1011 children followed from birth in the prospective BABYDIAB and BABYDIET studies using longitudinal models. Cox proportional hazard models, adjusted for study, sex, gestational age, birth weight percentile, and maternal type 1 diabetes status, were calculated to assess hazard ratios (HR) for islet autoimmunity with corresponding 95% confidence intervals (95% CI) by 2 SD increases in growth parameters. In a subset of n = 170 infants, we investigated whether the growth hormones insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-binding protein-3 (IGFBP-3) were in the causal pathway.

RESULTS

We found an early age at infant body mass index (BMI) peak to be associated with the development of islet autoimmunity [HR 0.60 (95% CI 0.41-0.87), per 2 SD increase in age]. Islet autoimmunity was also associated with BMI difference between infant BMI peak and childhood BMI rebound [HR 1.52 (95% CI 1.04-2.22)], but not after adjustment for age at infant BMI peak, and not with other parameters such as peak height and weight velocity during infancy. Serum concentrations of IGF-1 and IGFBP-3 at birth, 9 months, and 2 yr, respectively, were not significantly different between children with and without later islet autoimmunity.

CONCLUSIONS

Variations in early growth rate have subtle effects on the risk of islet autoimmunity with growth hormones unlikely to be in the causal pathway.

Residual β-cell mass influences growth of prepubertal children with type 1 diabetes

BACKGROUND

The growth deceleration observed in children with type 1 diabetes (T1D) has been related to poor glycemic control. It is unclear whether growth impairment persists despite the optimization of therapy. We analyzed the effects of intensive insulin treatment on prepubertal growth.

METHODS

One hundred and four T1D children were evaluated from T1D diagnosis up to puberty onset. Height, weight, insulin requirement and glycated hemoglobin (HbA1c) were recorded at 3- to 6-month intervals. Residual β-cell mass was estimated by fasting C-peptide at T1D onset.

RESULTS

Age at T1D onset was 5.91 ± 1.9 years. Follow-up duration was 4.84 ± 1.58 years. Height velocity standard deviation score (SDS) was -0.14 ± 1.84. Height SDS changed from 0.52 ± 1.04 at T1D onset, to 0.36 ± 1.10 at the end of follow-up (p = 0.04). BMI SDS increased from -0.04 ± 1.48 to 0.32 ± 1.03 (p = 0.01). Multivariate analysis showed that height velocity was directly affected by C-peptide (p = 0.03) and insulin requirement (p = 0.004) and inversely related to HbA1c (p = 0.006). BMI gain was negatively influenced by HbA1c (p = 0.01) and positively related to T1D duration (p = 0.01).

CONCLUSION

Despite insulin intensive therapy, T1D still negatively affects growth. Residual β-cell mass has a direct positive impact on growth, independently from the quality of glycemic control.

Diabetes in the young - a global view and worldwide estimates of numbers of children with type 1 diabetes

This paper describes the methodology, results and limitations of the 2013 International Diabetes Federation (IDF) Atlas (6th edition) estimates of the worldwide numbers of prevalent cases of type 1 diabetes in children (<15 years). The majority of relevant information in the published literature is in the form of incidence rates derived from registers of newly diagnosed cases. Studies were graded on quality criteria and, if no information was available in the published literature, extrapolation was used to assign a country the rate from an adjacent country with similar characteristics. Prevalence rates were then derived from these incidence rates and applied to United Nations 2012 Revision population estimates for 2013 for each country to obtain estimates of the number of prevalent cases. Data availability was highest for the countries in Europe (76%) and lowest for the countries in sub-Saharan Africa (8%). The prevalence estimates indicate that there are almost 500,000 children aged under 15 years with type 1 diabetes worldwide, the largest numbers being in Europe (129,000) and North America (108,700). Countries with the highest estimated numbers of new cases annually were the United States (13,000), India (10,900) and Brazil (5000). Compared with the prevalence estimates made in previous editions of the IDF Diabetes Atlas, the numbers have increased in most of the IDF Regions, often reflecting the incidence rate increases that have been well-documented in many countries. Monogenic diabetes is increasingly being recognised among those with clinical features of type 1 or type 2 diabetes as genetic studies become available, but population-based data on incidence and prevalence show wide variation due to lack of standardisation in the studies. Similarly, studies on type 2 diabetes in childhood suggest increased incidence and prevalence in many countries, especially in Indigenous peoples and ethnic minorities, but detailed population-based studies remain limited.

Early postnatal growth in children with HLA-conferred susceptibility to type 1 diabetes

AIMS/HYPOTHESIS

An association between increased length/height and weight gain and risk of type 1 diabetes (T1D) has been reported in children. We set out to investigate the potential contribution of T1D human leukocyte antigen (HLA) risk genotypes to this association in two countries with a contrasting disease incidence.

METHODS

In Estonia and Finland, length and weight were monitored up to the age of 24 months in 688 subjects. According to their HLA genotypes, the children were divided into four groups, those with very high, high or moderate risk for T1D, as well as a neutral/control group. Relative length and weight (SDS) were assessed and compared at 3, 6, 12, 18 and 24 months using World Health Organization (WHO) growth curves.

RESULTS

The mean relative length at the age of 24 months was lower in the group with the very high risk HLA genotype compared to the controls (p < 0.05). The mean relative weight differed between those two groups at the age of 12, 18 and 24 months (p < 0.05). When Estonian and Finnish cohorts were analyzed separately, the relative length showed similar but non-significant trends in both countries, while in Estonia the changes in weight at some time points still remained significant (p < 0.05).

CONCLUSIONS

Children with the highest HLA-conferred risk for T1D gained less weight and length during the first 24 months of life, and this feature was more pronounced in the Estonian children.

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.

Birth weight influences the clinical phenotype and the metabolic control of patients with type 1 diabetes (T1D)

BACKGROUND

High birth weight has been related to an increased risk of type 1 diabetes (T1D), while suboptimal birth weight (both high and low) has been related to obesity, insulin resistance and type 2 diabetes. Insulin resistance, as a consequence of poor metabolic control, has been described in T1D patients. The aims of the study were to analyse the distribution of birth size for gestational age in a large group of T1D patients and to investigate the effect of birth weight on clinical phenotype.

METHODS

Six-hundred two Caucasian T1D patients were evaluated. Small for gestational age (SGA) and large for gestational age (LGA) were defined as birth weight at <3rd percentile and >97th percentile for gestational age, respectively. Birth weights between the 3rd and 97th percentiles were defined as appropriate for gestational age. The clinical characteristics of small, appropriate for gestational age and large were compared. Multivariable linear regression models were fitted to evaluate the independent effects of birth weight and other covariates (age at T1D onset, gender and T1D duration) on different clinical outcomes (body mass index, HbA(1c), insulin requirement, high-density lipoprotein cholesterol and triglycerides).

RESULTS

Thirteen subjects (2.16%) were small (SGA), and 39 (6.48%) were large (LGA). Daily insulin requirement (U/kg/day) was significantly higher in SGA, while body mass index and HbA(1c) were increased in LGA. Multivariable linear regression showed a significant negative effect of birth weight on daily insulin requirement (p < 0.001).

CONCLUSIONS

Suboptimal birth weight (both high and low) in T1D patients seems to be associated with clinical characteristics suggestive of insulin resistance.

On the etiology of type 1 diabetes: a new animal model signifying a decisive role for bacteria eliciting an adverse innate immunity response

The cause of type 1 diabetes (T1D) remains unknown; however, a decisive role for environmental factors is recognized. The increased incidence of T1D during the last decades, as well as regional differences, is paralleled by differences in the intestinal bacterial flora. A new animal model was established to test the hypothesis that bacteria entering the pancreatic ductal system could trigger β-cell destruction and to provide new insights to the immunopathology of the disease. Obtained findings were compared with those present in two patients dying at onset of T1D. Different bacterial species, present in the human duodenum, instilled into the ductal system of the pancreas in healthy rats rapidly induced cellular infiltration, consisting of mainly neutrophil polymorphonuclear cells and monocytes/macrophages, centered around the pancreatic ducts. Also, the islets of Langerhans attracted polymorphonuclear cells, possibly via release of IL-6, IL-8, and monocyte chemotactic protein 1. Small bleedings or large dilatations of the capillaries were frequently found within the islets, and several β-cells had severe hydropic degeneration (ie, swollen cytoplasm) but with preserved nuclei. A novel rat model for the initial events in T1D is presented, revealing marked similarities with the morphologic findings obtained in patients dying at onset of T1D and signifying a decisive role for bacteria in eliciting an adverse innate immunity response. The present findings support the hypothesis that T1D is an organ-specific inflammatory disease.

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.

Viruses and vitamin D in the etiology of type 1 diabetes mellitus and multiple sclerosis

Although specific viruses have been associated with autoimmune diseases, none fulfill Koch's criteria of causation. The etiologies of such diseases appear to be complex and multifactorial. For example, one might propose that the etiology of type 1 diabetes mellitus results from a toxic metabolite of nitrosamines during an enteroviral infection. Multiple sclerosis might result from a cascade of events involving several herpes virus infections activated during periods of vitamin D deficiency. We encourage investigators to consider Rotman's sufficient-component causal model when developing hypotheses for testing for the etiology of chronic diseases. Delineating the web of causation may lead to additional strategies for prevention and treatment of several autoimmune diseases.

Thirty years of prospective nationwide incidence of childhood type 1 diabetes: the accelerating increase by time tends to level off in Sweden

OBJECTIVE

During the past few decades, a rapidly increasing incidence of childhood type 1 diabetes (T1D) has been reported from many parts of the world. The change over time has been partly explained by changes in lifestyle causing rapid early growth and weight development. The current study models and analyzes the time trend by age, sex, and birth cohort in an exceptionally large study group.

RESEARCH DESIGN AND METHODS

The present analysis involved 14,721 incident cases of T1D with an onset of 0-14.9 years that were recorded in the nationwide Swedish Childhood Diabetes Registry from 1978 to 2007. Data were analyzed using generalized additive models.

RESULTS

Age- and sex-specific incidence rates varied from 21.6 (95% CI 19.4-23.9) during 1978-1980 to 43.9 (95% CI 40.7-47.3) during 2005-2007. Cumulative incidence by birth cohort shifted to a younger age at onset during the first 22 years, but from the birth year 2000 a statistically significant reversed trend (P < 0.01) was seen.

CONCLUSIONS

Childhood T1D increased dramatically and shifted to a younger age at onset the first 22 years of the study period. We report a reversed trend, starting in 2000, indicating a change in nongenetic risk factors affecting specifically young children.

Association between childhood obesity and subsequent Type 1 diabetes: a systematic review and meta-analysis

AIMS

To review and synthesize the published evidence on the possible association between childhood obesity and the subsequent risk of Type 1 diabetes.

METHODS

The PubMed database was systematically searched for studies using childhood obesity, BMI or %weight-for-height as the exposure variable and subsequent Type 1 diabetes as the outcome. Studies were only included if assessment of obesity preceded the diagnosis of Type 1 diabetes.

RESULTS

Eight case-control studies and one cohort study were included, comprising a total of 2658 cases. Of these nine studies, seven reported a significant association between childhood obesity, BMI or %weight-for-height and increased risk for Type 1 diabetes. Meta-analysis of the four studies that reported childhood obesity as a categorical exposure produced a pooled odds ratio of 2.03 (95% CI 1.46-2.80) for subsequent Type 1 diabetes; however, in those studies, age at obesity assessment varied from age 1 to 12 years. A dose-response relationship was supported by a continuous association between childhood BMI and subsequent Type 1 diabetes in a meta-analysis of five studies (pooled odds ratio 1.25 (95%CI 1.04-1.51) per 1 sd higher BMI).

CONCLUSION

There is overall evidence for an association between childhood obesity, or higher BMI, and increased risk of subsequent Type 1 diabetes. Several theories have been proposed for a causal relationship. Reduction in Type 1 diabetes should be considered as a potential additional benefit of preventing childhood obesity.

Increased maternal Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) associated with older age at diagnosis of Type 1 diabetes in offspring

AIMS

Obesity and insulin resistance have been linked to rising incidence and earlier onset of Type 1 diabetes. Inherited differences in insulin action might also influence the evolution of Type 1 diabetes.Our aim was to determine whether parental BMI and insulin resistance influences age of onset of Type 1 diabetes in their offspring.

METHODS

BMI standard deviation score and age at diagnosis of Type 1 diabetes was examined in 227 children, and in 206 of these was compared with local matched control subjects. Non-diabetic parents of a subgroup of 80 children with Type 1 diabetes were recruited. Parental BMI was compared with local adult control subjects. The relationship between parental BMI, waist-hip ratio, homeostasis model assessment of insulin resistance (HOMA-IR), leptin and adiponectin levels and age at diagnosis of Type 1 diabetes in offspring was examined.

RESULTS

We found no relationship between age at diagnosis of Type 1 diabetes in children and BMI standard deviation score (P = 0.5). Children with Type 1 diabetes and their parents were heavier than matched control subjects (mean BMI standard deviation score sd in children = 0.66 1.06 vs. 0.32 1.16 in control subjects, P = 0.002; mean parental BMI sd 27.7 0.4 vs. 25.5 0.4 kg ⁄m2 in control subjects; P < 0.0001). Maternal HOMA-IR accounted for 20% of variation in age at diagnosis (P < 0.001) with increasing maternal insulin resistance associated with later age at diagnosis of Type 1 diabetes.

CONCLUSIONS

Childrenwith Type 1 diabetes and their parents have an increased BMI at diagnosis.Maternal insulin resistance is associated with later onset of Type 1 diabetes in children.

Insulin-requiring diabetes in Ethiopia: associations with poverty, early undernutrition and anthropometric disproportion

BACKGROUND/OBJECTIVES

Most insulin-requiring diabetes patients in Ethiopia have an atypical form of the disease, which resembles previous descriptions of malnutrition-related diabetes. As so little is known about its aetiology, we have carried out a case-control study to evaluate its social and nutritional determinants.

SUBJECTS/METHODS

Men and women with insulin-requiring diabetes (n=107), aged 18-40 years, were recruited in two centres, Gondar and Jimma, 750 km northwest and 330 km southwest of the capital, Addis Ababa, respectively. Controls of similar age and sex (n=110) were recruited from patients attending other hospital clinics.

RESULTS

Diabetes was strongly associated with subsistence farming, odds ratio=3.5 (95% confidence interval: 1.5-7.8) and illiteracy/low levels of education, odds ratio=4.0 (2.0-8.0). Diabetes was also linked with a history of childhood malnutrition, odds ratio=5.5 (1.0-29.0) the mother's death during childhood, odds ratio=3.9 (1.0-14.8), and markers of poverty including poorer access to sanitation (P=0.004), clean water (P=0.009), greater overcrowding (P=0.04), increased distance from the clinic (P=0.01) and having fewer possessions (P=0.01). Compared with controls, people with diabetes had low mid upper arm circumference, body mass index (BMI) and fat/lean body mass (P<0.01). In addition, men with the disease tended to be shorter, were lighter (P=0.001), with reduced sitting height (P=0.015) and reduced biacromial (P=0.003) and bitrochanteric (P=0.008) diameters.

CONCLUSIONS

Insulin-requiring diabetes in Ethiopia is strongly linked with poor education and markers of poverty. Men with the disease have associated disproportionate skeletal growth. These findings point towards a nutritional aetiology for this condition although the nature of the nutritional deficiency and its timing during growth and development remains obscure.

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.

Childhood growth and age at diagnosis with Type 1 diabetes in Colorado young people

OBJECTIVE

Studies have suggested that the age at diagnosis of Type 1 diabetes (T1D) is decreasing over time. The overload hypothesis postulates that risk factors, such as accelerated growth, may be responsible for this decrease. We assessed changes in age, body mass index (BMI), weight and height at diagnosis with T1D in non-Hispanic white (NHW) and Hispanic (HISP) young people from Colorado, using data from the IDDM Registry and SEARCH Study.

METHODS

In three time periods, 656 (1978-1983), 562 (1984-1988) and 712 (2002-2004) young people aged 2-17 years were newly diagnosed with T1D. Age, weight, height and presence of diabetic ketoacidosis (DKA) at diagnosis with T1D were obtained from medical records. Trends over the three time periods were assessed with regression analyses.

RESULTS

Age at diagnosis decreased by 9.6 months over time (P = 0.0002). Mean BMI standard deviation score (SDS), weight SDS and height SDS increased over time (P < 0.0001), while prevalence of DKA decreased (P < 0.0001). Increasing height over time accounted for 15% (P = 0.04) of the decreasing age at diagnosis with T1D.

CONCLUSIONS

Our study provides evidence that increased linear growth, but not increased BMI or weight over time, may account, at least in part, for the younger age at diagnosis of T1D in Colorado children. This finding supports the hypothesis that increasing environmental pressure resulting from changes in potentially preventable risk factors may accelerate the onset of T1D in children.

Long-term trends in the incidence of type 1 diabetes in Denmark: the seasonal variation changes over time

There is a worldwide increase of type 1 diabetes mellitus (T1DM). In 1996, the Danish population-based registry was initiated including all newly diagnosed children aged 0-15 yr. This is the report of incidence and seasonal variation for the first 10 yr of the registry. The data was analyzed using Poisson's regression analysis. A total of 2166 children with diabetes were diagnosed before the age of 15 yr between 1996 and 2005. In this period, the annual increase in childhood T1DM was 3.43% (95% confidence interval: 1.91-4.97), which was unaffected by age and gender. Seasonal variation in incidence rates varied by year but not by age and gender. In conclusion, there is a steep increase in incidence of childhood T1DM in Denmark; the increase is comparable with the increase seen in other European countries. There is a significant seasonal variation that changes on a year-to-year basis. The observed variations in cadence rates may be associated with viral epidemics, sunshine exposure, or vitamin D levels and suggest further exploration of these relations.

Childhood body mass index (BMI), breastfeeding and risk of Type 1 diabetes: findings from a longitudinal national birth cohort

AIMS

To perform a longitudinal analysis of the association between childhood body mass index (BMI) and later risk of Type 1 diabetes, controlling for socio-economic status, birthweight, height in early and late childhood, breastfeeding history and pubertal status.

METHODS

Analysis of the 1970 British Birth Cohort, followed up at age 5, 10 and 30 years (n = 11,261). Data were available on birthweight, breastfeeding; height, weight, pubertal status, socio-economic status at age 10 years; self-report data on history of diabetes (type, age at onset) at age 30 years. Cox proportional hazards models were used to examine relations of childhood growth, socio-economic status and breastfeeding history to the incidence of Type 1 diabetes between 10 and 30 years of age.

RESULTS

Sixty-one subjects (0.5%) reported Type 1 diabetes at 30 years of age; 47 (77%) reported onset >or= age 10 years. Higher BMI z-score at 10 years predicted higher risk of subsequent Type 1 diabetes (hazard ratio 1.8, 95% confidence interval 1.2 to 2.8, P = 0.01) when adjusted for birthweight, pubertal status, breastfeeding history and socio-economic status. Repeating the model for childhood obesity, the hazard ratio was 3.1 (1.0, 9.3; P = 0.05). Birthweight, breastfeeding, height growth and pubertal timing were not associated with incidence of Type 1 diabetes.

CONCLUSIONS

Higher BMI in childhood independently increased the risk of later Type 1 diabetes, supporting suggestions that obesity may provide a link between Type 1 and Type 2 diabetes. This supports observations of a rise in Type 1 diabetes prevalence. Reduction in childhood obesity may reduce the incidence of Type 1 as well as Type 2 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.

Type 1 diabetes: increased height and weight gains in early childhood

OBJECTIVE

The accelerator/beta-cell stress hypothesis regards insulin resistance as one common basis for type 1 and type 2 diabetes and weight increase as an important trigger of type 1 diabetes. To test this hypothesis, we examined children's height and weight gain from birth to the time of diagnosis of type 1 diabetes.

METHOD

Growth charts (n = 316) from children 0-16 yr old up to the time of diagnosis of type 1 diabetes were compared with growth charts from age- and sex-matched controls.

RESULTS

Compared with their controls, children who developed diabetes had experienced more pronounced gain in both weight and height. In the year of diagnosis, they were taller [0.5 vs. 0.36 standard deviation score (SDS), p < 0.03] and heavier (0.7 vs. 0.45 SDS, p < 0.01). Children who developed diabetes aged 5 yr or less gained more weight during the period between their third month and third year of life (p < 0.01). Children who were diagnosed between 6 and 10 yr of age had gained more in height before they were 5 yr old (p < 0.05). Regression analysis showed that a high weight or a high body mass index (BMI) at 5 yr of age indicated, more than the other measurements, a high risk for diabetes later during childhood, while height and weight at ages less than 5 yr did not add any further information on diabetes risk.

CONCLUSIONS

Rapid growth before 7 yr of age and increased BMI in childhood are risk factors for later type 1 diabetes. These findings support the accelerator/beta-cell stress hypothesis.

Time trends in the incidence of type 1 diabetes in Finnish children: a cohort study

BACKGROUND

Finland has the highest incidence of type 1 diabetes worldwide, reaching 40 per 100,000 people per year in the 1990s. Our aim was to assess the temporal trend in type 1 diabetes incidence since 2000 in Finnish children aged younger than 15 years and to predict the number of cases of type 1 diabetes in the future.

METHODS

Children with newly diagnosed type 1 diabetes in Finland who were listed on the National Public Health Institute diabetes register, Central Drug Register, and Hospital Discharge Register in 1980-2005 were included in a cohort study. We excluded patients with type 2 diabetes and diabetes occurring secondary to other conditions, such as steroid use, Down's syndrome, and congenital malformations of pancreas.

FINDINGS

10,737 children-5816 boys and 4921 girls-were diagnosed with type 1 diabetes before 15 years of age during 1980-2005. The average age-standardised incidence was 42.9 per 100,000 per year (95% CI 42.6-44.3) during this period, increasing from 31.4 per 100,000 per year in 1980 to 64.2 per 100,000 per year in 2005. The age-specific rates per 100,000 per year were 31.0, 50.5, and 50.6 at ages 0-4 years, 5-9 years, and 10-14-years, respectively. We noted a significant non-linear component to the time trend (p<0.0003). In children aged 0-4 years, the increase was largest, at 4.7% more affected every year. The overall boy-to-girl ratio of incidence was 1.1; at the age of 13 years, it was 1.7 (1.4-2.0). The predicted cumulative number of new cases with type 1 diabetes before 15 years of age between 2006 and 2020 was about 10 800.

INTERPRETATION

The incidence of type 1 diabetes in Finnish children is increasing even faster than before. The number of new cases diagnosed at or before 14 years of age will double in the next 15 years and the age of onset will be younger (0-4 years).

Worldwide childhood type 1 diabetes incidence--what can we learn from epidemiology?

Type 1 diabetes is the most common form of diabetes in most part of the world, although reliable data are still unavailable in several countries. Wide variations exist between the incidence rates of different populations, incidence is lowest in China and Venezuela (0.1 per 100,000 per year) and highest in Finland and Sardinia (37 per 100,000 per year). In most populations girls and boys are equally affected. In general, the incidence increases with age, the incidence peak is at puberty. After the pubertal years, the incidence rate significantly drops in young women, but remains relatively high in young adult males up to the age 29-35 years. Prospective national and large international registries (DIAMOND and EURODIAB) demonstrated an increasing trend in incidence in most regions of the world over the last few decades and increases seem to be the highest in the youngest age group. Analytical epidemiological studies have identified environmental risk factors operating early in life which might have contributed to the increasing trend in incidence. These include enteroviral infections in pregnant women, older maternal age (39-42 years), preeclampsia, cesarean section delivery, increased birthweight, early introduction of cow's milk proteins and an increased rate of postnatal growth (weight and height). Optimal vitamin D supplementation during early life has been shown to be protective. Some of these environmental risk factors such as viruses may initiate autoimmunity toward the beta cell, other exposures may put on overload on the already affected beta cell and thus accelerate the disease process.

Relationship between increased relative birthweight and infections during pregnancy in children with a high-risk diabetes HLA genotype

AIMS/HYPOTHESIS

Children with high-risk type 1 diabetes HLA genotype have increased risk of high relative birthweight (HrBW), while cord blood islet autoantibodies decrease the risk. As gestational infections may affect offspring type 1 diabetes risk, the aims were to test whether: (1) children of mothers reporting gestational infections have increased HrBW; (2) gestational infections explain islet autoantibody reduction of HrBW; and (3) gestational infections affect the association between HLA and HrBW.

SUBJECTS AND METHODS

HLA genotypes and autoantibodies to glutamic acid decarboxylase, insulinoma-associated protein 2 and insulin were determined in cord blood of children born to non-diabetic mothers in the Diabetes Prediction in Skåne (DiPiS) study. Mothers reported gestational infections when the child was 2 months old.

RESULTS

Fever or gastroenteritis during pregnancy was reported by 2,848/19,756 mothers (14%); 339 in more than one trimester. Children whose mothers reported infections had increased risk of HrBW (p = 0.0003), particularly in the absence of cord blood islet autoantibodies (interaction between HrBW, islet autoantibodies and infections, p = 0.0005). The effect on HrBW by high-risk HLA-DQ2/8 was aggravated by infections in more than one trimester (odds ratio [OR] = 5.24; p = 0.003) (interaction; p = 0.022). When infections were reported, cord blood islet autoantibodies decreased HrBW (OR = 0.34; p = 0.0002).

CONCLUSIONS/INTERPRETATION

This study revealed that: (1) gestational fever, gastroenteritis, or both, increased the risk of HrBW; (2) cord blood islet autoantibodies decreased the risk of HrBW only in combination with infections; and (3) infections aggravated the association between HLA-DQ2/8 and HrBW. These data suggest an interaction between HLA, gestational infections, islet autoantibodies and fetal growth.

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.

Marked increase in type 1 diabetes mellitus incidence in children aged 0-14 yr in Victoria, Australia, from 1999 to 2002

OBJECTIVES

The objectives of the study were to (i) determine the incidence of type 1 diabetes mellitus (T1DM) in children aged <15 yr in Victoria, Australia, from 1999 to 2002 and (ii) to analyze trends in incidence over this period.

METHODS

Prospective population-based incidence study. The primary source of case ascertainment was from the Australasian Paediatric Endocrine Group (APEG) Victorian diabetes register. The secondary source was the National Diabetes Register (NDR), which ascertains cases from the National Diabetes Service Scheme (NDSS), a Commonwealth government initiative, where patients register to receive diabetes supplies at a subsidized price.

MAIN OUTCOME MEASURES

Age-standardized incidence, trends in incidence by age, sex and year, and variation in incidence by region, season, and socioeconomic status.

RESULTS

Case ascertainment was 99.1% complete using the capture-recapture method. The mean annual age-standardized incidence was 19.3 per 100 000 person years from 1999 to 2002. On average, incidence increased by 9.3% per year, with a greater relative increase in the 0-4 yr age-group (p = 0.037). No gender bias in incidence was found, but the increase in females was statistically significant (13.6% per year, 95% confidence interval 3.7-24.3). Variation in geographical distribution and seasonal onset of incidence was not statistically significant.

CONCLUSIONS

The marked increase in the incidence of T1DM in Victoria is greater than that recently described in other Australia states and developed nations. The etiology of this rise is unclear, while the increased caseload has major implications for diabetes health care providers for current and future resource allocation.

Growth in the first year of life and the risk of type 1 diabetes in a Danish population

The aim of the study was to investigate whether growth parameters at birth and age 1 year were associated with type 1 diabetes (T1D) in the Danish population and to what extent this explains the increase in T1D incidence. The study is a population-based case-control study; it compares 490 cases from the Danish diabetes register 1996-99 aged 0-14 years and 696 randomly selected controls (2 per case) from the population register matched for gender and date of birth. We found an increased risk of T1D during childhood in children with a body mass index (BMI) on or above two standard deviations at age 1 year (OR = 3.77 [95% CI 1.41, 10.1]). Children developing diabetes were significantly taller at age 1 year (OR = 1.04 [95% CI 1.00, 1.08]). Children born 1981-99 have significantly higher BMI and weight at birth and a significantly lower BMI and weight at age 1 year compared with children born 1966-74. Thus the increasing incidence of T1D could not be explained by changes in growth parameters at birth or at age 1 year.

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.

Investigation of the age-at-onset heterogeneity in type 1 diabetes through mathematical modeling

The heterogeneity between young- and adult-onset type 1 diabetes (T1D) is well known, but not well understood. We approach this question through mathematical formulation and analysis of the dynamic interactions between the immune cells and the pancreatic islet beta-cells that lead to the beta-cell destruction. Utilizing the perturbation expansion method we investigate the dynamic stability of our system under fast and slow beta-cell turnover limits. We find that if autoimmunity is initiated when the turnover is slow (adult age), a stable steady state can exist with reduced number of beta-cells, where the beta-cell regeneration balances the ongoing autoimmune destruction. This implies that a slow disease process is possible. In contrast, if autoimmunity occurs when the beta-cell turnover is rapid (young age), such a stable state will never be attained and the destruction will progress unabated, leading to an acute disease onset. The major findings of our model are consistent with clinical observations, and it offers an explanation for the dynamic and phenotypic heterogeneity between young- and adult-onset T1D. More importantly, the model analyses point out that pathways regulating beta-cell turnover can be new targets to interfere with the disease process of T1D.

Can we slow the rising incidence of childhood-onset autoimmune diabetes? The overload hypothesis

Overload of the beta cell, mediated by a variety of mechanisms, may sensitise it to immune damage and apoptosis, and thus accelerate ongoing autoimmune processes leading to its destruction. Environmental risk determinants that may exert such overload effects include insulin resistance due to excess fat cell accumulation, and increased insulin requirement due to a high growth rate, physical stress (infection, inflammation) or psychological stress. The increasing incidence of childhood diabetes, and the shift to younger age at onset, is unlikely to be driven by environmental risk factors that have been associated with initiation of autoimmunity, e.g. virus infections or early infant feeding. Risk factors that may accelerate beta cell destruction have shown a steady increase in the population, and are more plausible causes of such a pattern of change. Child growth, weight and birthweight are well-established estimates of community wealth and increase in most countries of Europe. Overfeeding of children early in life leads to both accelerated growth and weight, and even a moderate excess of child growth, not necessarily associated with obesity, is associated with risk of type 1 diabetes. New, safe and effective immune-modulating drugs for possible arrest of the autoimmune process may become available in time, but in the interim these accelerating factors may be targeted. Public health programmes for pregnant mothers and young families, aiming at changing overfeeding and the sedentary lifestyle of the children would be preferable to other alternatives. Interventions such as these would be safe and could potentially influence future risks of type 1 and type 2 diabetes and other major threats to adult health.

The 'accelerator hypothesis': relationship between weight, height, body mass index and age at diagnosis in a large cohort of 9,248 German and Austrian children with type 1 diabetes mellitus

AIMS/HYPOTHESIS

The aim of this study was to investigate whether either increased weight or BMI are associated with the earlier manifestation of type 1 diabetes mellitus in children.

METHODS

We evaluated anthropometric measurements in a large cohort of 9,248 patients of European extraction who were diagnosed in the years 1990-2003 in 116 pediatric clinics throughout Germany and Austria.

RESULTS

Patients were divided into four groups according to age (0-4.9 years, 5-9.9 years, 10-14.9 years and 15-20 years). Significantly higher standard deviation scores (SDSs) for weight and BMI at diabetes onset were found for both boys and girls in the three younger age groups (up to 14.9 years of age) compared with the reference population (p<0.00001). In addition, the BMI SDS and the weight SDS were significantly higher in the 0-4.9-years age group than in all other groups (p<0.00001), and BMI SDS at onset gradually decreased with increasing age at manifestation (p<0.0001). Over the >10-year study period, there was a continuous rise in the weight-SDS and the BMI-SDS in the cohort (p<0.0001), especially in the 5-9.9-years and the 10-14.9-years age groups. Multivariate analysis revealed a significant influence of male sex and of year of manifestation on BMI SDS (p<0.0001) and demonstrated a negative association between the patients' BMI SDS and age at diagnosis, with a mean annual decrease in BMI SDS of -0.0248 (95% CI -0.0294 to -0.0202, p<0.0001).

CONCLUSIONS/INTERPRETATION

A higher BMI was associated with a younger age at diabetes onset. Increased weight gain could therefore be a risk factor for the early manifestation of type 1 diabetes.

Diabetes-associated HLA genotypes affect birthweight in the general population

AIMS/HYPOTHESIS

The aim of our study was to test the hypothesis that HLA genotypes conferring risk of diabetes, cord blood autoantibodies, or both are associated with increased birthweight.

METHODS

HLA genotypes were determined in dried blood spots of cord blood from a total of 16,709 children born to healthy mothers in the Diabetes Prediction in Skåne (DiPiS) study, a population-based observational clinical investigation of newborn children. Children born to mothers with diabetes or gestational diabetes were excluded. Autoantibodies to glutamic acid decarboxylase (GAD65Ab) and insulinoma-associated protein 2 were determined in standard radioligand binding assays. Birthweight was adjusted for gestational age and divided into quartiles. The upper quartile was defined as high relative birthweight (HrBW) and the lower quartile as low relative birthweight (LrBW).

RESULTS

Genotypes conferring risk of type 1 diabetes were strongly associated with relative birthweight (rBW) (p=0.01). The high-risk HLA-DQ2/8, DQ8/0604 and DQ8/X genotypes were associated with HrBW (odds ratio [OR] [95% CI]=1.20 [1.08-1.33], p=0.0006). The HLA-DQB1*0603 allele, which is negatively associated with type 1 diabetes, was also associated with HrBW (p=0.025), confirming a previous report on DQB1*0603-linked HLA-DR13. GAD65Ab were negatively associated with HrBW (OR [95% CI]=0.72 [0.56-0.93], p=0.01). Regression analysis showed that the HLA-associated increase in rBW was independent of confounding factors.

CONCLUSIONS/INTERPRETATION

HLA genotypes may be associated with intrauterine growth independent of type 1 diabetes risk. The epidemiological observation that high birthweight is a risk factor for type 1 diabetes could possibly result from a moderating effect on intrauterine growth of HLA genotypes conferring a high risk of diabetes.

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

AIMS/HYPOTHESIS

We investigated the association between type 1 diabetes and birthweight by age at disease onset.

METHODS

This population-based case-referent study used data from two nationwide case registers that are linked to the Swedish Medical Birth Registry and cover incident cases of type 1 diabetes in the 0- to 14-year (since 1 July 1977) and 15- to 34-year age groups (since 1 January 1983). Of the cases linked to the Medical Birth Registry, a total of 9,283 cases with onset before 15 years of age was recorded before 1 January 2003, and 1,610 cases were recorded with onset before 30 years of age and born after 1973 (together 95% of eligible cases). Multiple births and babies of diabetic mothers were excluded. Sex-specific birthweight by gestational week is expressed as multiples of the standard deviation (SDS) and adjusted for year of birth, maternal age and parity.

RESULTS

Cases with onset before 10 years of age (n = 5,792) showed a significant linear trend in odds ratio (OR) by SDS of adjusted birthweight (OR by SDS: 0.062; 95% CI: 0.037-0.086; p < 0.0001), while cases with onset at the age of 10-29 years showed no significant trend (OR by SDS: 0.004; 95% CI: -0.007 to 0.0014; p = 0.22).

CONCLUSIONS/INTERPRETATION

The association between type 1 diabetes risk and birthweight seems to be limited to cases with disease onset in younger years.

Diet, growth, and the risk for type 1 diabetes in childhood: a matched case-referent study

OBJECTIVE

To study the association between type 1 diabetes risk and previous intake of energy, accounting for body size and previous intake of nutrients and foods, accounting for the energy intake.

RESEARCH DESIGN AND METHODS

We conducted an incident population-based case-referent study in Stockholm, Sweden, including 99 of 100 eligible 7- to 14-year-old diabetic children and 180 of 200 age-, sex-, and area-matched referent children identified through the Swedish population register. Average daily energy and nutrient intake 1 year before diabetes diagnosis/interview was estimated using the food frequency questionnaire with assessment of consumed food amounts. Mean SD scores of growth measurements taken during the last 4 years before the diagnosis were used. Odds ratios (ORs) were calculated by conditional logistic regression.

RESULTS

Average intake of energy, carbohydrate, fat, and protein was significantly higher among the case subjects as well as mean weight-for-age SD score. Higher energy intake and weight-for-age were both associated with increased diabetes risk after adjustment for each other: OR (95% CI) for medium and high levels of energy intake were 1.33 (0.52-3.42) and 5.23 (1.67-16.38), respectively, and for weight-for-age were 3.20 (1.30-7.88) and 3.09 (1.16-8.22), respectively. High intake of carbohydrates, especially disaccharides and sucrose, increased diabetes risk.

CONCLUSIONS

Higher energy intake and larger body size were independently associated with increased diabetes risk. Of the different nutrients, higher intake of carbohydrates, particularly disaccharides and sucrose, increased the risk. Lifestyle habits leading to higher energy intake and more rapid growth in childhood may contribute to the increase of childhood-onset type 1 diabetes by different mechanisms.

Genetic and perinatal factors as risk for childhood type 1 diabetes

The mechanisms by which gestational infections, blood incompatibility, birth weight, mother's age and other prenatal or neonatal events increase the risk for type 1 diabetes are not understood. Studies so far have been retrospective, and there is a lack of population-based prospective studies. The possibility of identifying children at type 1 diabetes risk among first-degree relatives has resulted in prospective studies aimed at identifying postnatal events associated with the appearance of autoantibody markers for type 1 diabetes and a possible later onset of diabetes. However, the majority (85%) of new onset type 1 diabetes children do not have a first-degree relative with the disease. Population-based studies are therefore designed to prospectively analyse pregnant mothers and their offspring. One such study is DiPiS (Diabetes Prediction in Skåne), which is examining a total of about 10,000 pregnancies expected every year in the Skåne (Scania) region of Sweden that has 1.1 million inhabitants. Blood samples from all mothers in this region are obtained during pregnancy and at the time of delivery. Cord blood is analysed for HLA high-risk alleles and for autoantibodies against the 65 kD isoform of glutamic acid decarboxylase (GADA), the protein tyrosine phosphatase-related IA-2 antigen (IA-2A) and insulin (IAA) as a measure of prenatal autoimmune exposure. Identifying high-risk children by genetic, autoimmune and gestational risk factors followed by prospective analyses will make it possible to test the hypothesis that gestational events may trigger beta cell autoimmunity as a prerequisite for childhood type 1 diabetes.