The effect of day care exposure on the risk of developing type 1 diabetes: a meta-analysis of case-control studies

Birth Order, Caesarean Section, or Daycare Attendance in Relation to Child- and Adult-Onset Type 1 Diabetes: Results from the German National Cohort

(1) Background: Global incidence of type 1 diabetes (T1D) is rising and nearly half occurred in adults. However, it is unclear if certain early-life childhood T1D risk factors were also associated with adult-onset T1D. This study aimed to assess associations between birth order, delivery mode or daycare attendance and type 1 diabetes (T1D) risk in a population-based cohort and whether these were similar for childhood- and adult-onset T1D (cut-off age 15); (2) Methods: Data were obtained from the German National Cohort (NAKO Gesundheitsstudie) baseline assessment. Self-reported diabetes was classified as T1D if: diagnosis age ≤ 40 years and has been receiving insulin treatment since less than one year after diagnosis. Cox regression was applied for T1D risk analysis; (3) Results: Analyses included 101,411 participants (100 childhood- and 271 adult-onset T1D cases). Compared to "only-children", HRs for second- or later-born individuals were 0.70 (95% CI = 0.50-0.96) and 0.65 (95% CI = 0.45-0.94), respectively, regardless of parental diabetes, migration background, birth year and perinatal factors. In further analyses, higher birth order reduced T1D risk in children and adults born in recent decades. Caesarean section and daycare attendance showed no clear associations with T1D risk; (4) Conclusions: Birth order should be considered in both children and adults' T1D risk assessment for early detection.

Day care as a strategy for drowning prevention in children under 6 years of age in low- and middle-income countries

BACKGROUND

Drowning is responsible for an estimated 320,000 deaths a year, and over 90% of drowning mortality occurs in low- to middle-income countries (LMICs), with peak drowning rates among children aged 1 to 4 years. In this age group, mortality due to drowning is particularly common in rural settings and about 75% of drowning accidents happen in natural bodies of water close to the home. Providing adequate child supervision can protect children from drowning, and organized formal day care programs could offer a way to achieve this.

OBJECTIVES

Primary objective • To assess the effects of day care programs for children under 6 years of age on drowning-related mortality or morbidity, or on total drowning accidents (fatal and non-fatal), in LMICs, compared to no day care programs or other drowning prevention interventions Secondary objectives • To assess the effects of day care programs in LMICs for children under 6 years of age on unsafe water exposure • To assess safety within these programs (e.g. transmission of infection within day care, physical or sexual abuse of children within day care) • To assess the incidence of unintentional injury within these programs • To describe the cost-effectiveness of such programs, in relation to averted drowning-related mortality or morbidity SEARCH METHODS: On November 23, 2019, and for an update on August 18, 2020, we searched MEDLINE (PubMed), Embase, CENTRAL, ERIC, and CINAHL, as well as two trial registries. On December 16, 2019, and for an update on February 9, 2021, we searched 12 other resources, including websites of organizations that develop programs targeted to children.

SELECTION CRITERIA

We included randomized, quasi-randomized, and non-randomized controlled studies (with explicitly listed specific study design features) that implemented formal day care programs as a single program or combined with additional out-of-day care components (such as educational activities aimed at preventing injury or drowning or early childhood development activities) for children of preschool age (below 6 years of age) in LMICs for comparison with no such programs or with other drowning prevention interventions. Studies had to report at least one outcome related to drowning or injury prevention for the children enrolled.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection and data extraction, as well as risk of bias and GRADE assessment.

MAIN RESULTS

Two non-randomized observational studies, conducted in rural Bangladesh, involving a total of 252,631 participants, met the inclusion criteria for this review. One of these studies compared a formal day care program combined with parent education, playpens provided to parents, and community-based activities as additional out-of-day care components versus no such program. Overall we assessed this study to be at moderate risk of bias (moderate risk of bias due to confounding, low risk of bias for other domains). This study showed that implementation of a formal day care program combined with parent education, provision of playpens to parents, and community-based activities, in a rural area with a high drowning incidence, likely reduces the risk of death from drowning over the study period of 4 years and 8 months compared to no day care program (hazard ratio 0.18, 95% confidence interval [CI] 0.06 to 0.58; 1 study, 136,577 participants; moderate-certainty evidence). Drowning morbidity (non-fatal drowning resulting in complications), total drowning (fatal and non-fatal), unsafe water exposure, and program safety (e.g. transmission of infection within day care, physical or sexual abuse of children within day care) were not reported, nor was the incidence of other unintentional injuries. Cost-effectiveness was reported as 812 USD (95% CI 589 to 1777) per disability-adjusted life-year averted as a consequence of drowning (moderate-certainty evidence). The second study compared day care programs with or without playpens provided to parents as an additional component versus only playpens provided to parents as an alternative drowning prevention intervention. Overall we assessed the study to be at critical risk of bias because we judged bias due to confounding to be at critical risk. As the certainty of evidence was very low, we are uncertain about the effects on drowning mortality rate of implementing a day care program compared to providing playpens (rate ratio 0.25, 95% CI 0.15 to 0.41; 1 study; 76,575 participants; very low-certainty evidence). Likewise, we are uncertain about the effects of a day care program with playpens provided as an additional component versus playpens provided alone (rate ratio 0.06, 95% CI 0.02 to 0.12; 1 study, 45,460 participants; very low-certainty evidence). The other outcomes of interest - drowning morbidity, total drowning, unsafe water exposure, program safety, incidence of other unintentional injuries, and cost-effectiveness - were not reported.

AUTHORS' CONCLUSIONS

This review provides evidence suggesting that a day care program with additional out-of-day care components such as community-based education, parent education, and playpens provided to parents likely reduces the drowning mortality risk in regions with a high burden of drowning compared to no intervention.

Why is the Incidence of Type 1 Diabetes Increasing?

Type 1 diabetes is a condition that can lead to serious long-term complications and can have significant psychological and quality of life implications. Its incidence is increasing in all parts of the world, but the reasons for this are incompletely understood. Genetic factors alone cannot explain such a rapid increase in incidence; therefore, environmental factors must be implicated. Lifestyle factors have been classically associated with type 2 diabetes. However, there are data implicating obesity and insulin resistance to type 1 diabetes as well (accelerator hypothesis). Cholesterol has also been shown to be correlated with the incidence of type 1 diabetes; this may be mediated by immunomodulatory effects of cholesterol. There is considerable interest in early life factors, including maternal diet, mode of delivery, infant feeding, childhood diet, microbial exposure (hygiene hypothesis), and use of anti-microbials in early childhood. Distance from the sea has recently been shown to be negatively correlated with the incidence of type 1 diabetes. This may contribute to the increasing incidence of type 1 diabetes since people are increasingly living closer to the sea. Postulated mediating mechanisms include hours of sunshine (and possibly vitamin D levels), mean temperature, dietary habits, and pollution. Ozone, polychlorinated biphenyls, phthalates, trichloroethylene, dioxin, heavy metals, bisphenol, nitrates/nitrites, and mercury are amongst the chemicals which may increase the risk of type 1 diabetes. Another area of research concerns the role of the skin and gut microbiome. The microbiome is affected by many of the factors mentioned above, including the mode of delivery, infant feeding, exposure to microbes, antibiotic use, and dietary habits. Research on the reasons why the incidence of type 1 diabetes is increasing not only sheds light on its pathogenesis but also offers insights into ways we can prevent type 1 diabetes.

Higher parental occupational social contact is associated with a reduced risk of incident pediatric type 1 diabetes: Mediation through molecular enteroviral indices

We aimed to examine the association between parental occupational social contact and hygiene factors on type 1 diabetes (T1D) risk and possible mediation of these effects through child enteroviral infection. We interviewed 333 incident T1D cases and 660 controls from 2008–2011 in Melbourne, Australia. Enteroviral indices (ribonucleic acid by reverse transcription polymerase chain reaction and Coxsackie B virus antibody levels) in peripheral blood were measured in nested case control samples. Parent occupational social contact was assessed by the number of well or sick children, adults or animals contacted daily through work. Higher parental occupational social contact was strongly associated with reduced T1D risk with evidence of dose response (contact with the well or sick score, Adjusted odds ratio (AOR) per category: 0.73 (95% Confidence Interval (CI): 0.66, 0.81); P<0.001 or AOR 0.63 (95% CI: 0.53, 0.75); P<0.001) respectively). Nine of the ten parental social contact indices, were significant mediated through one or more enteroviral indices. The strength of association between enterovirus presence and T1D onset increased with child age (1.2 fold increase per year; P = 0.05). Lower child hand hygiene enhanced the adverse effect of low parental occupational contact with the sick; Synergy Index 5.16 (95% CI: 3.61, 7.36). The interaction between hand washing and parental occupational contact is more consistent with protection against parental enteroviral shedding than the sharing of a protective infectious agent or microbiome.

Environmental Factors Associated with Type 1 Diabetes Development: A Case Control Study in Egypt

Uncertainty still exists regarding the role of some environmental risk in the development of type 1 diabetes mellitus (T1DM) both globally and in Egypt. The objective here was to explore the potential environmental risk factors associated with the development of T1DM among children in Egypt. A case-controlled study of 204 T1DM children and an equal number of age and sex-matched controls was conducted in Assiut, Egypt. Data regarding the parental, gestational, neonatal, and childhood possible risk factors for T1DM were evaluated. The final sex adjusted multivariable logistic regression model revealed that the risk for T1DM was significantly higher among rural residents (aOR = 2.03, 95% CI: 1.30-4.25), those with parental history of T1DM (aOR = 9.03, 95% CI: 1.02-83.32), birth through cesarean section (aOR = 2.13, 95% CI: 1.09-5.03), and having history of early introduction of cow milk in the first year of life (aOR = 19.49, 95% CI: 8.73-45.53). On the other hand, a protective effect was observed between at least six months' breastfeeding, vitamin D supplementation in the first year of life, high physical activity, and the development of T1DM. Educational programs should be adopted to improve awareness and knowledge of the parents to avoid the increased risk factors and encourage protective practices.

Diabetes mellitus in childhood: an emerging condition in the 21st century

The International Diabetes Federation (IDF-2015) estimates the existence of 30,900 children under 15 years old with type 1 diabetes mellitus (DM1) in Brazil, and an increase of 3.0% per year is expected. This review focused on meta-analysis and pediatric diabetes update articles in order to draw attention to the need of planning coping strategies to support this serious public health problem in coming years. DM1 is considered an immuno-mediated disease with a complex transmission influenced by genetic and environmental factors responsible for a gradual destruction of the insulin producing pancreatic beta cells. Seroconversion to DM1-associated autoantibodies and abnormalities in metabolic tests that assess insulin secretion and glucose tolerance can be used as predictive criteria of beta cells functional reserve and the onset of the clinical disease. Symptomatic DM1 treatment is complex and the maintenance of good metabolic control is still the only effective strategy for preserving beta cell function. Disease duration and hyperglycemia are both risk factors for the onset of chronic vascular complications that negatively affect the quality of life and survival of these patients. In this regard, health teams must be trained to provide the best possible information on pediatric diabetes, through continuing education programs focused on enabling these young people and their families to diabetes self-management.

Systematic review and meta-analysis of the association between mumps during childhood and risk of type 1 diabetes mellitus

We conducted a systematic review and meta-analysis of the association between mumps and risk of type 1 diabetes mellitus (T1DM). Literature searches were conducted using Medline, EMBASE and Web of Science including studies published before February 2014. Crude and, where available, adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were extracted from the published reports of each included study. Combined OR estimates and tests of heterogeneity were obtained using meta-analysis techniques. The analysis was repeated in subgroups of studies on the basis of quality defined by the score on the Newcastle-Ottawa scale (NOS). In total, 18 articles met the eligibility criteria, and overall there was some evidence of a weak association between clinically diagnosed mumps and T1DM (OR=1.23, 95% CI 1.00-1.51; p=0.05) but marked heterogeneity between studies (I2=49%; p for heterogeneity=0.01). Restricting analyses to 13 high quality studies, there was little evidence of association between clinically diagnosed mumps and T1DM (OR=1.11, 95% CI 0.91-1.35; p=0.29) and there was much less heterogeneity (I2=26%; p for heterogeneity=0.18). Overall there was little evidence of any strong association between mumps infection and T1DM.

Adverse events following immunization: real causality and myths

INTRODUCTION

To assure the highest safety of immunization programs, detect adverse events following immunization (AEFIs), eliminate concerns, and reduce the risk of low vaccination coverage, authorities in industrialized countries have collected years of reports of suspected AEFIs and have systematically assessed their clinical importance.

AREAS COVERED

In this paper, the methods used to assess vaccine safety and the results obtained by the analysis of reports, studies, and meta-analyses are discussed.

EXPERT OPINION

Severe AEFIs are rare, and all evaluations of safety of vaccines recommended for both children and adults have demonstrated that the advantages of vaccines are always significantly higher than the problems that they cause, and there is no need to modify recommendations. However, the definition of AEFI is dependent on the vaccines themselves, complicating the definition of an AEFI and explaining why doubts and concerns have been raised. Presently, disease epidemiology data collected in healthy people and in subjects with underlying disease, general vaccine coverage, and the vaccination status of subjects with AEFIs are managed by many independent institutions. Only strict co-operation between these institutions will lead to the successful identification of AEFIs and to a reduction of the weight of anti-vaccine arguments.

Vaccinations and childhood type 1 diabetes mellitus: a meta-analysis of observational studies

AIMS/HYPOTHESIS

The aim of this study was to investigate the association between routine vaccinations and the risk of childhood type 1 diabetes mellitus by systematically reviewing the published literature and performing meta-analyses where possible.

METHODS

A comprehensive literature search was performed of MEDLINE and EMBASE to identify all studies that compared vaccination rates in children who subsequently developed type 1 diabetes mellitus and in control children. ORs and 95% CIs were obtained from published reports or derived from individual patient data and then combined using a random effects meta-analysis.

RESULTS

In total, 23 studies investigating 16 vaccinations met the inclusion criteria. Eleven of these contributed to meta-analyses which included data from between 359 and 11,828 childhood diabetes cases. Overall, there was no evidence to suggest an association between any of the childhood vaccinations investigated and type 1 diabetes mellitus. The pooled ORs ranged from 0.58 (95% CI 0.24, 1.40) for the measles, mumps and rubella (MMR) vaccination in five studies up to 1.04 (95% CI 0.94, 1.14) for the haemophilus influenza B (HiB) vaccination in 11 studies. Significant heterogeneity was present in most of the pooled analyses, but was markedly reduced when analyses were restricted to study reports with high methodology quality scores. Neither this restriction by quality nor the original authors' adjustments for potential confounding made a substantial difference to the pooled ORs.

CONCLUSIONS/INTERPRETATION

This study provides no evidence of an association between routine vaccinations and childhood type 1 diabetes.

Daycare attendance, breastfeeding, and the development of type 1 diabetes: the diabetes autoimmunity study in the young

BACKGROUND

The hygiene hypothesis attributes the increased incidence of type 1 diabetes (T1D) to a decrease of immune system stimuli from infections. We evaluated this prospectively in the Diabetes Autoimmunity Study in the Young (DAISY) by examining daycare attendance during the first two years of life (as a proxy for infections) and the risk of T1D.

METHODS

DAISY is a prospective cohort of children at increased T1D risk. Analyses were limited to 1783 children with complete daycare and breastfeeding data from birth to 2 years of age; 58 children developed T1D. Daycare was defined as supervised time with at least one other child at least 3 times a week. Breastfeeding duration was evaluated as a modifier of the effect of daycare. Cox proportional hazards regression was used for analyses.

RESULTS

Attending daycare before the age of 2 years was not associated with T1D risk (HR: 0.89; CI: 0.54-1.47) after adjusting for HLA, first degree relative with T1D, ethnicity, and breastfeeding duration. Breastfeeding duration modified this association, where daycare attendance was associated with increased T1D risk in nonbreastfed children and a decreasing T1D risk with increasing breastfeeding duration (interaction P value=0.02).

CONCLUSIONS

These preliminary data suggest breastfeeding may modify the effect of daycare on T1D risk.

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.

How do childhood diagnoses of type 1 diabetes cluster in time?

Background

Previous studies have indicated that type 1 diabetes may have an infectious origin. The presence of temporal clustering—an irregular temporal distribution of cases—would provide additional evidence that occurrence may be linked with an agent that displays epidemicity. We tested for the presence and form of temporal clustering using population-based data from northeast England.

Materials and Methods

The study analysed data on children aged 0–14 years diagnosed with type 1 diabetes during the period 1990–2007 and resident in a defined geographical region of northeast England (Northumberland, Newcastle upon Tyne, and North Tyneside). Tests for temporal clustering by time of diagnosis were applied using a modified version of the Potthoff-Whittinghill method.

Results

The study analysed 468 cases of children diagnosed with type 1 diabetes. There was highly statistically significant evidence of temporal clustering over periods of a few months and over longer time intervals (p<0.001). The clustering within years did not show a consistent seasonal pattern.

Conclusions

The study adds to the growing body of literature that supports the involvement of infectious agents in the aetiology of type 1 diabetes in children. Specifically it suggests that the precipitating agent or agents involved might be an infection that occurs in “mini-epidemics”.

Expanding the hygiene hypothesis: early exposure to infectious agents predicts delayed-type hypersensitivity to Candida among children in Kilimanjaro

Background

Multiple lines of evidence suggest that infections in early life prevent the development of pathological immune responses to allergens and autoantigens (the hygiene hypothesis). Early infections may also affect later immune responses to pathogen antigen.

Methods

To evaluate an association between early infections and immune responses to pathogen antigen, delayed-type hypersensitivity (DTH) to Candida albicans was evaluated among 283 2- to 7-year-old children in Kilimanjaro, Tanzania. A questionnaire and physical examination were used to characterize variables reflecting early exposure to infectious agents (family size, house construction materials, BCG vaccination, hospitalization history). Logistic regression was used to evaluate the association between early exposure to infectious agents and DTH to C. albicans.

Results

Triceps skinfold thickness (OR: 1.11; 95% CI: 1.01, 1.22) and age (OR: 1.27; 95% CI: 1.04, 1.55) were positively associated with DTH to C. albicans. Adjusted for age and sex, large family size (OR: 2.81; 95% CI: 1.04, 7.61), BCG vaccination scar (OR: 3.10; 95% CI: 1.10, 8.71), and hospitalization during infancy with an infectious disease (OR: 4.67; 95% CI: 1.00, 21.74) were positively associated with DTH to C. albicans.

Conclusions

Early life infections were positively associated with later DTH to C. albicans. This result supports an expansion of the hygiene hypothesis to explain not only pathological immune responses to allergens, but also appropriate immune responses to pathogens. Immune system development may be responsive to early infections as an adaptive means to tailor reactivity to the local infectious disease ecology.

Interbirth interval is associated with childhood type 1 diabetes risk

Short interbirth interval has been associated with maternal complications and childhood autism and leukemia, possibly due to deficiencies in maternal micronutrients at conception or increased exposure to sibling infections. A possible association between interbirth interval and subsequent risk of childhood type 1 diabetes has not been investigated. A secondary analysis of 14 published observational studies of perinatal risk factors for type 1 diabetes was conducted. Risk estimates of diabetes by category of interbirth interval were calculated for each study. Random effects models were used to calculate pooled odds ratios (ORs) and investigate heterogeneity between studies. Overall, 2,787 children with type 1 diabetes were included. There was a reduction in the risk of childhood type 1 diabetes in children born to mothers after interbirth intervals <3 years compared with longer interbirth intervals (OR 0.82 [95% CI 0.72-0.93]). Adjustments for various potential confounders little altered this estimate. In conclusion, there was evidence of a 20% reduction in the risk of childhood diabetes in children born to mothers after interbirth intervals <3 years.

Neighborhood level risk factors for type 1 diabetes in youth: the SEARCH case-control study

BACKGROUND

European ecologic studies suggest higher socioeconomic status is associated with higher incidence of type 1 diabetes. Using data from a case-control study of diabetes among racially/ethnically diverse youth in the United States (U.S.), we aimed to evaluate the independent impact of neighborhood characteristics on type 1 diabetes risk. Data were available for 507 youth with type 1 diabetes and 208 healthy controls aged 10-22 years recruited in South Carolina and Colorado in 2003-2006. Home addresses were used to identify Census tracts of residence. Neighborhood-level variables were obtained from 2000 U.S. Census. Multivariate generalized linear mixed models were applied.

RESULTS

Controlling for individual risk factors (age, gender, race/ethnicity, infant feeding, birth weight, maternal age, number of household residents, parental education, income, state), higher neighborhood household income (p = 0.005), proportion of population in managerial jobs (p = 0.02), with at least high school education (p = 0.005), working outside the county (p = 0.04) and vehicle ownership (p = 0.03) were each independently associated with increased odds of type 1 diabetes. Conversely, higher percent minority population (p = 0.0003), income from social security (p = 0.002), proportion of crowded households (0.0497) and poverty (p = 0.008) were associated with a decreased odds.

CONCLUSIONS

Our study suggests that neighborhood characteristics related to greater affluence, occupation, and education are associated with higher type 1 diabetes risk. Further research is needed to understand mechanisms underlying the influence of neighborhood context.

Prevention of type 1 diabetes

Prevention of loss of b cells in type 1 diabetes is a major goal of current research. Knowledge of the genetic susceptibility, increasing ability to predict who may be at risk, recognition of the potential clinical impact of residual insulin secretion after diagnosis, and development of new immunomodulatory agents have supported an increasing number of clinical trials to prevent b-cell loss. Interventions can be targeted at 3 stages: before the development of autoimmunity (primary prevention), after autoimmunity is recognized (secondary prevention), or after diagnosis when significant numbers of b cells remain (tertiary prevention). Thus far, several agents show promise when given shortly after diagnosis, but no interventions before diagnosis have shown benefit. Knowledge in this area has grown quickly in recent years and will continue to grow rapidly with several international collaborative efforts underway.

Environmental factors associated with childhood-onset type 1 diabetes mellitus: an exploration of the hygiene and overload hypotheses

OBJECTIVE

To assess the relationship between selected maternal and infant characteristics and risk of type 1 diabetes mellitus, specifically characteristics identified from birth records that may pertain to the hygiene or overload hypotheses.

DESIGN

Population-based case-control study.

SETTING

Washington State from 1987 to 2005.

PARTICIPANTS

All children younger than 19 years hospitalized for type 1 diabetes (International Classification of Diseases, Ninth Revision codes 250.x1 and 250.x3) identified (n=1852) from hospital discharge data and linked with their birth certificates. Controls (n=7408) were randomly selected from birth records, frequency matched on year of birth.

MAIN EXPOSURES

Maternal factors included age, race, educational attainment, marital status, use of Medicaid insurance, body mass index, prepregnancy weight, prior births, timing and adequacy of prenatal care, and cesarean delivery. Infant factors included birth weight, size for gestational age, and gestational age.

MAIN OUTCOME MEASURE

The main outcome was first hospitalization for type 1 diabetes mellitus; adjusted odds ratios were estimated for the association of selected maternal and infant characteristics with type 1 diabetes.

RESULTS

Consistent with the hygiene hypothesis, type 1 diabetes was negatively associated with having older siblings (for >or=3 siblings, odds ratio [OR], 0.56; 95% confidence interval [CI], 0.45-0.70) and with indicators of lower economic status or care access, such as an unmarried mother (OR, 0.79; 95% CI, 0.69-0.91), inadequate prenatal care (OR, 0.53; 95% CI, 0.40-0.71), or Medicaid insurance (OR, 0.67; 95% CI, 0.58-0.77). Related to the overload hypothesis, maternal body mass index of 30 or higher (OR, 1.29; 95% CI, 1.01-1.64) was associated with increased risk of diabetes.

CONCLUSION

Environmental factors related to decreased antigenic stimulation in early life and maternal obesity may be associated with type 1 diabetes.

Prevention of type 1 diabetes

Prevention of loss of beta cells in type 1 diabetes is a major goal of current research. Knowledge of the genetic susceptibility, increasing ability to predict who may be at risk, recognition of the potential clinical impact of residual insulin secretion after diagnosis, and development of new immunomodulatory agents have supported an increasing number of clinical trials to prevent beta-cell loss. Interventions can be targeted at 3 stages: before the development of autoimmunity (primary prevention), after autoimmunity is recognized (secondary prevention), or after diagnosis when significant numbers of beta cells remain (tertiary prevention). Thus far, several agents show promise when given shortly after diagnosis, but no interventions before diagnosis have shown benefit. Knowledge in this area has grown quickly in recent years and will continue to grow rapidly with several international collaborative efforts underway.

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.

Atopy, home environment and the risk of childhood-onset type 1 diabetes: a population-based case-control study

BACKGROUND

The marked increases in the incidence of type 1 diabetes in recent decades strongly suggest the role of environmental influences. These environmental influences remain largely unknown.

OBJECTIVE

To investigate atopy and home environment (such as children living at home, sharing a bedroom and house moves) as potential risk factors for type 1 diabetes.

SUBJECTS AND METHOD

In Northern Ireland, 175 children with type 1 diabetes and 4859 control children completed a questionnaire on atopy experience, family composition and home environment. Control children from two age groups (6-8 yr old and 13-14 yr old) were identified from randomly selected primary and secondary schools across Northern Ireland. Cases were identified from a population-based type 1 diabetes register.

RESULTS

There was little evidence of a difference in the proportion of participants with a history of atopy in the cases compared with controls. There was a significant reduction in the risk of diabetes in children who lived with more siblings {odds ratio (OR) = 0.58 [95% confidence interval (95% CI) 0.39-0.85] in children who lived with three or more siblings compared with one or none} and in children who moved house more often [OR = 0.59 (95% CI 0.40-0.88) in children who moved house twice or more compared with never].

CONCLUSION

The reduced risk of type 1 diabetes in children living with siblings, sharing a bedroom and moving house more often could reflect the protection afforded by exposure to infections in early life and consequently may provide support for the hygiene hypothesis.

Early infant feeding and risk of type 1 diabetes mellitus-a nationwide population-based case-control study in pre-school children

BACKGROUND

The evidence on the role of environmental factors in the development of type 1 diabetes is conflicting. Reducing potential bias and the variety of exposures, we investigated the association between type 1 diabetes risk and nutritional and environmental exposures in pre-school children.

METHODS

This nationwide population-based case-control study included 760 cases under 5 years of age newly diagnosed with type 1 diabetes during 1992-1995. From the general population, 1,871 controls were randomly selected and individually matched on age ( +/- 1 year), sex, and residence. Information on infant diet, foetal, perinatal and socio-economic factors, and familial diabetes was obtained by a parent-administered questionnaire. Data were analysed by multiple conditional logistic regression.

RESULTS

Duration of breastfeeding and age at introduction of bottle-feeding were inversely associated with type 1 diabetes risk according to a dose-response relationship (trend test p < 0.05). Adjusted odd ratios (95% CI) for a long breastfeeding period and a late introduction of bottle-feeding (>or=5 month versus < 2 weeks) were 0.71 (0.54-0.93) and 0.80 (0.62-1.04), respectively. Familial type 1 diabetes, maternal age > 40 years, and low birth weight were found more frequently among diabetic than among control children. Current cow's milk consumption, higher social status, and a larger family were associated with a reduced diabetes risk. Up to one half of the diabetic cases in the population could be attributed to modifiable exposures.

CONCLUSIONS

Our findings indicate that infant feeding is associated with type 1 diabetes risk and that a considerable part of new type 1 diabetic cases is potentially preventable.

No association between routinely recorded infections in early life and subsequent risk of childhood-onset Type 1 diabetes: a matched case-control study using the UK General Practice Research Database

AIMS

To determine whether children with infections in early life (recorded routinely in general practice) have a reduced risk of Type 1 diabetes, as would be expected from the hygiene hypothesis.

METHODS

Children with Type 1 diabetes and up to 20 matched (on year of birth, sex and region) control subjects were selected from a cohort of children born in the UK at General Practice Research Database practices. For each child, the frequency of general practitioner consultations for infections and prescriptions for antibiotics in the first year of life were determined. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated using conditional logistic regression.

RESULTS

The main analysis included 367 case and 4579 matched control subjects. There was no evidence of any reduction in the subsequent risk of Type 1 diabetes in children with at least one infection in the first year of life (OR = 1.03, 95%CI 0.79, 1.34) or in children prescribed antibiotics in the first year of life (OR = 1.03, 95%CI 0.82, 1.29). Further analyses also revealed little evidence of a difference in subsequent risk of Type 1 diabetes after different types of infection in the first year of life (including gastrointestinal, conjunctivitis, otitis media and upper and lower respiratory tract). Analyses of infections in the first 2 years of life reached similar conclusions.

CONCLUSIONS

This study provides no evidence of an association between infections in early life and subsequent risk of childhood-onset Type 1 diabetes and therefore does not support the hygiene hypothesis.

Incidence of type 1 diabetes mellitus in the 0- to 17-yr-old Israel population, 1997-2003

BACKGROUND

Recent reports from different countries have shown an increased incidence of type 1 diabetes mellitus (T1DM). A national juvenile diabetes register was established by the Israel Pediatric Endocrine Society and the Israel Center for Disease Control (ICDC) in 1997.

OBJECTIVE

This article reports the epidemiology of T1DM in children in the age-group 0-17 yr in Israel during 1997-2003.

METHODS

The Israel juvenile diabetes register is a population-based anonymous registry. Newly diagnosed cases of all types of diabetes in children and adolescents are reported to the ICDC by all the endocrinologists in all the pediatric diabetes centers. Overall incidence rates and rates by sex, age, and population group are presented. Comparisons are made by year, sex, age, and population group.

RESULTS

During 1997-2003, 1485 children and adolescents with T1DM were reported in the age-group 0-17 yr. The annual incidence rate of T1DM increased by 34% during 1997-2003, from 8.0 per 100 000 [95% confidence interval (CI) 6.8-9.3] to 10.7 per 100 000 (95% CI 9.4-12.1). Incidence rates were higher for Jews than for Arabs. Among Jews, children of Yemenite origin had the highest incidence rate (26.1 per 100 000; 95% CI 13.3-38.9). Incidence peaked at an earlier age in girls. A first-degree family history of T1DM was found in 9.1% of the cases.

CONCLUSIONS

The incidence of T1DM is increasing in the Israeli population, particularly in the Arab population. The culturally varied composition of the Israeli population provides important areas for future studies based on data collected in this national register.

Type 1 diabetes

Type 1 diabetes accounts for only about 5-10% of all cases of diabetes; however, its incidence continues to increase worldwide and it has serious short-term and long-term implications. The disorder has a strong genetic component, inherited mainly through the HLA complex, but the factors that trigger onset of clinical disease remain largely unknown. Management of type 1 diabetes is best undertaken in the context of a multidisciplinary health team and requires continuing attention to many aspects, including insulin administration, blood glucose monitoring, meal planning, and screening for comorbid conditions and diabetes-related complications. These complications consist of microvascular and macrovascular disease, which account for the major morbidity and mortality associated with type 1 diabetes. Newer treatment approaches have facilitated improved outcomes in terms of both glycaemic control and reduced risks for development of complications. Nonetheless, major challenges remain in the development of approaches to the prevention and management of type 1 diabetes and its complications.

Absence of breast-feeding is associated with the risk of type 1 diabetes: a case-control study in a population with rapidly increasing incidence

There are indications that the effect of environmental factors on the risk of type 1 diabetes mellitus (T1DM) is increasing over time. This can be documented by the rapid increase of T1DM incidence in genetically stable populations. Our aim was to study an association of T1DM with the variable factors of the perinatal period and of early infancy, using data from children born over a period of changing exposure to some of the studied factors. A case-control dataset was analysed, consisting of 868 diabetic children and 1,466 anonymous controls, mostly schoolmates of the children with T1DM. The data were collected using structured questionnaires completed by parents. After performing univariate analyses, the associations were analysed using multiple logistic regression adjusted for potential confounders, including the year of birth. The risk of T1DM decreased with increasing duration of breast-feeding, while no breast-feeding was associated with an increased T1DM risk, OR=1.93 [95% CI: 1.33-2.80], breast-feeding for more than 12 months was protective, OR=0.42 [95% CI: 0.22-0.81], both being relative to the reference category of breast-feeding for 1-3 months. A short duration of day-care attendance (none or less than 1 year) was weakly associated with the risk of T1DM, OR=1.65 [95% CI: 1.05-2.62]. No association was detected between T1DM and signs of prenatal infections, perinatal stress factors, birth size and weight, indicators of crowding or the presence of a domestic pet in the household. Short breast-feeding period and short attendance to day care is associated with the risk of T1DM in Czech children.

Relationship between the incidence of type 1 diabetes and maternal enterovirus antibodies: time trends and geographical variation

AIMS/HYPOTHESIS

We have previously observed an inverse correlation between the incidence of type 1 diabetes and enterovirus infections in the background population. The aim of this study was to analyse whether maternal enterovirus antibody status, which reflects both the frequency of enterovirus infections and the protection conferred by the mother on the offspring, also correlates with the incidence of type 1 diabetes.

METHODS

Maternal enterovirus antibodies were analysed from serum samples taken from pregnant women between 1983 and 2001 in Finland and Sweden using enzyme immunoassay and neutralisation assays. Comparable samples were also taken between 1999 and 2001 in countries with a lower incidence of diabetes (Estonia, Germany, Hungary, Israel, Lithuania, Russia).

RESULTS

A clear decrease was observed in maternal enterovirus antibody levels over the past 20 years (p<0.0001). The frequency of enterovirus antibodies was higher in countries with a low or intermediate incidence of type 1 diabetes compared with high-incidence countries (p<0.0001).

CONCLUSIONS/INTERPRETATION

These findings are in line with our previous observations supporting the hypothesis that a low frequency of enterovirus infection in the background population increases the susceptibility of young children to the diabetogenic effect of enteroviruses.

Parental age at delivery, birth order, birth weight and gestational age are associated with the risk of childhood Type 1 diabetes: a UK regional retrospective cohort study

AIMS

To investigate perinatal risk factors for childhood Type 1 diabetes in a UK population cohort.

METHODS

Perinatal data have been routinely recorded in Northern Ireland for all births in the period 1971-86 (n = 447 663). Diabetes status at the age of 15 years was ascertained in this cohort by identifying 991 children from 1079 registered with Type 1 diabetes diagnosed from 1971 to 2001 and date of birth in the period 1971-86.

RESULTS

Increased Type 1 diabetes risk was associated with higher maternal age, paternal age, birth weight and birth weight for gestational and lower gestational age. After adjustment for maternal age, the association between Type 1 diabetes and paternal age remained significant [relative risk (RR) = 1.52 (1.10, 2.09) comparing father's age 35 years or more to less than 25 years] but not vice versa [RR = 1.11 (0.80, 1.54) comparing mother's age 35 years or more to less than 25 years]. Increased birth order was associated with a significant decrease in the risk of Type 1 diabetes [adjusted RR = 0.75 (0.62, 0.90) comparing birth order three or more with firstborn], but this only became apparent when adjustment was made for maternal age. Furthermore this association with birth order was significant only for diabetes diagnosed under the age of 5 years.

CONCLUSIONS

Our analysis demonstrates, for the first time in a UK regional cohort setting, that maternal age and paternal age at delivery, birth order, birth weight and gestational age are significantly associated with Type 1 diabetes risk.

Symptoms of common maternal infections in pregnancy and risk of islet autoimmunity in early childhood

OBJECTIVE

The aim of this study was to test whether symptoms of maternal infections during pregnancy and indicators of postnatal infections predict development of islet autoimmunity in children at genetically increased risk of type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 871 children with type 1 diabetes-associated HLA genotypes born in Denver, Colorado, and 391 siblings or offspring of individuals with type 1 diabetes referred from clinics in the Denver metropolitan area were enrolled soon after birth and seen in the clinic at age <or=15 months. Information on indicators of infection was collected by structured interviews soon after birth and at ages 3-15 months. Clinic visits were scheduled at ages 9, 15, and 24 months, and yearly thereafter. The outcome was positivity for one or more islet autoantibodies (to GAD(65), insulin, or IA-2/ICA512) at two or more consecutive visits. During a mean follow-up of 4.2 years, 52 children developed islet autoimmunity.

RESULTS

Children whose mother reported at least one symptom of infection during pregnancy (mostly respiratory or gastrointestinal) had a significantly lower risk of islet autoimmunity compared with other children (hazard ratio 0.48; 95% CI 0.27-0.83). After stratification, the association appeared among girls (0.21; 0.09-0.48) but not among boys (1.09; 0.47-2.51) with a P value for interaction of 0.005. Symptoms of neonatal infections, early daycare attendance, exposure to cats or dogs, and household crowding were not related to islet autoimmunity.

CONCLUSIONS

Symptoms of maternal infections in pregnancy predicted a significantly lower risk of islet autoimmunity in young girls, suggesting a protective effect of such infections.