A low incidence of Type 1 diabetes between 1977 and 2001 in south-eastern Sweden in areas with high population density and which are more deprived

Parental socio-economic position and the risk of type 1 diabetes in children and young adults in Denmark: A nation-wide register-based study

AIM

Diabetes mellitus type 1 is one of the most common serious chronic diseases in childhood and the incidence is increasing. Insight into risk factors may inform our etiologic understanding of the disease and subsequent prevention. Any socio-economic gradient in disease risk indicates a potential for prevention, since this points towards socially patterned environmental risk factors. The aim of this study was to investigate the association between measures of parental socio-economic position and the onset of type 1 diabetes in offspring based on individual data in the entire Danish population.

METHODS

In a study population of all children born in Denmark between 1 January 1987 and 31 December 2010, we examined the association between parental socio-economic position and the risk of type 1 diabetes up to the age of 25 years. The risk of type 1 diabetes was estimated according to maternal education, paternal education and household income using Cox proportional hazards regression, with adjustments for the a priori selected confounding variables: year of birth, maternal age at birth and parental type 1 diabetes.

RESULTS

In the study population of 1,433,584 children, a total of 4610 developed type 1 diabetes. We found no clear pattern in type 1 diabetes risk according to parental educational attainment or parental household income.

CONCLUSIONS

In this large population covering study of the risk of type 1 diabetes according to individual-level parental socio-economic position, we found no strong indication of a socially patterned disease risk.

Is Population Density Associated with Non-Communicable Disease in Western Developed Countries? A Systematic Review

Over the last three decades, researchers have investigated population density and health outcomes at differing scale. There has not been a systematic review conducted in order to synthesise this evidence. Following the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines, we systematically reviewed quantitative evidence published since 1990 on population density and non-communicable disease (NCD) within Westernised countries. Fifty-four studies met the inclusion criteria and were evaluated utilising a quality assessment tool for ecological studies. High population density appears to be associated with higher mortality rates of a range of cancers, cardiovascular disease and COPD, and a higher incidence of a range of cancers, asthma and club foot. In contrast, diabetes incidence was found to be associated with low population density. High and low population density are therefore risk markers for a range of NCDs, indicating that there are unidentified factors and mechanisms underlying aetiology. On closer examination, our synthesis revealed important and complex relationships between population density, the built environment, the nature of greenspace and man-made exposures. In light of increasing rates of morbidity and mortality, future research is required to investigate these associations in order to establish causative agents for each NCD.

Twenty years of pediatric diabetes surveillance: what do we know and why it matters

SEARCH for Diabetes in Youth (SEARCH) was initiated in 2000 as a multicenter study to address major gaps in the understanding of childhood diabetes in the United States. An active registry of youth diagnosed with diabetes at age <20 years since 2002 assessed prevalence, annual incidence, and trends by age, race/ethnicity, sex, and diabetes type. An observational cohort nested within the population-based registry was established to assess the natural history and risk factors for acute and chronic diabetes-related complications, as well as the quality of care and quality of life of children and adolescents with diabetes from diagnosis into young adulthood. SEARCH findings have contributed to a better understanding of the complex and heterogeneous nature of youth-onset diabetes. Continued surveillance of the burden and risk of type 1 and type 2 diabetes is important to track and monitor incidence and prevalence within the population. SEARCH reported evidence of early diabetes complications highlighting that continuing the long-term follow-up of youth with diabetes is necessary to further our understanding of its natural history and to develop the most appropriate approaches to primary, secondary, and tertiary prevention of diabetes and its complications. This review summarizes two decades of research and suggests avenues for further work.

Associations of area deprivation and urban/rural traits with the incidence of type 1 diabetes: analysis at the municipality level in North Rhine-Westphalia, Germany

AIM

To analyse the associations of area deprivation and urban/rural traits with the incidence of type 1 diabetes in the German federal state of North Rhine-Westphalia.

METHODS

Data of incident type 1 diabetes cases in children and adolescents aged <20 years between 2007 and 2014 were extracted from a population-based diabetes register. Population data, indicators of area deprivation and urban/rural traits at the municipality level (396 entities) were obtained from official statistics. Area deprivation was assessed in five groups based on quintiles of an index of multiple deprivation and its seven deprivation domains. Poisson regression accounting for spatial dependence was applied to investigate associations of area deprivation and urban/rural traits with type 1 diabetes incidence.

RESULTS

Between 2007 and 2014, 6143 incident cases were reported (99% completeness); the crude incidence was 22.3 cases per 100 000 person-years. The incidence decreased with increasing employment and environmental deprivation (relative risk of the most vs. the least deprived municipalities: 0.905 [95% CI: 0.813, 1.007] and 0.839 [0.752, 0.937], respectively) but was not associated with the composite deprivation index. The incidence was higher in more peripheral, rural, smaller and less densely populated municipalities, and the strongest association was estimated for the location trait (relative risk of peripheral/very peripheral compared with very central location: 1.231 [1.044, 1.452]).

CONCLUSIONS

The results suggest that the type 1 diabetes risk is higher in more remote, more rural, less densely populated and less deprived areas. Urban/rural traits were stronger predictors of type 1 diabetes risk than area deprivation indicators.

Geographical variation in the incidence of type 1 diabetes in the Nordic countries: A study within NordicDiabKids

BACKGROUND

The incidence of type 1 diabetes (T1D) is high in the Nordic countries with geographic differences between as well as within countries.

OBJECTIVE

To describe the geographical distribution of the incidence of T1D among children in four Nordic countries, an area where the population is considered genetically similar.

METHODS

Data on children 0 to 14 years of age and diagnosed with T1D 2006 to 2011 was collected from four Nordic national pediatric quality diabetes registries. Data included year of diagnosis (2006-2011), sex, and age at diagnosis. Figures for number of children at risk during 2006 to 2011-as well as total population, proportion with foreign background and size of populated areas of geographic regions-were collected from official statistics.

RESULTS

The total incidence during the study period for all four countries was 35.7/100 000 person years but differed between the countries (range 18.2-44.1; P < .001). The incidence difference between the countries was most obvious in the highest age group, 10 to 14 years of age, whereas there was no difference in the youngest age group 0 to 5 years of age. Iceland had similar incidence in the entire country, whereas the other countries had areas with different incidence. Densely populated areas, such as major cities, had the lowest incidence.

CONCLUSION

The incidence of T1D differed between the Nordic countries and also between the neighboring countries and generally decreased with population density. This indicates that environmental factors may contribute to the level of incidence of T1D.

Correlating the global increase in type 1 diabetes incidence across age groups with national economic prosperity: A systematic review

BACKGROUND

The global epidemiology of type 1 diabetes (T1D) is not yet well known, as no precise data are available from many countries. T1D is, however, characterized by an important variation in incidences among countries and a dramatic increase of these incidences during the last decades, predominantly in younger children. In the United States and Europe, the increase has been associated with the gross domestic product (GDP) per capita. In our previous systematic review, geographical variation of incidence was correlated with socio-economic factors.

AIM

To investigate variation in the incidence of T1D in age categories and search to what extent these variations correlated with the GDP per capita.

METHODS

A systematic review was performed to retrieve information about the global incidence of T1D among those younger than 14 years of age. The study was carried out according to the PRISMA recommendations. For the analysis, the incidence was organized in the periods: 1975-1999 and 2000-2017. We searched the incidence of T1D in the age-groups 0-4, 5-9 and 10-14. We compared the incidences in countries for which information was available for the two periods. We obtained the GDP from the World Bank. We analysed the relationship between the incidence of T1D with the GDP in countries reporting data at the national level.

RESULTS

We retrieved information for 84 out of 194 countries around the world. We found a wide geographic variation in the incidence of T1D and a worldwide increase during the two periods. The largest contribution to this increase was observed in the youngest group of children with T1D, with a relative increase of almost double when comparing the two periods (P value = 2.5 × e^-5). Twenty-six countries had information on the incidence of T1D at the national level for the two periods. There was a positive correlation between GDP and the incidence of T1D in both periods (Spearman correlation = 0.52 from 1975-1999 and Spearman correlation = 0.53 from 2000-2017).

CONCLUSION

The incidence increase was higher in the youngest group (0-4 years of age), and the highest incidences of T1D were found in wealthier countries.

Onset of type 1 diabetes mellitus in rural areas of the USA

BACKGROUND

In the USA, the epidemiologic features of type 1 diabetes are not well-defined across all 50 states. However, the advent of large nationwide insurance databases enables the investigation of where type 1 diabetes cases occur throughout the country.

METHODS

An integrated database from a large nationwide health insurer in the USA (Clinformatics Data Mart Database) was used, from 2001 to 2017. The database contained longitudinal information on approximately 77 million people.

RESULTS

The incidence of type 1 diabetes was greatest in areas of low population density across the 50 states. Individuals in the lowest population density areas had rates that were 2.28 times (95% CI 2.08 to 2.50) that of persons living in high-density areas. This association was consistent across various measures of rural status (p<0.001 for population density; p<0.001 for per cent rural as defined by the US Census Bureau; p=0.026 for farmland). The association between rural areas and the incidence of type 1 diabetes was evident across all four general regions of the USA.

CONCLUSIONS

The predilection of type 1 diabetes in rural areas provides clues to potential factors associated with the onset of this autoimmune disease.

Environmental (Lifestyle) Risk Factors for LADA

BACKGROUND

In order to prevent diabetes it is important to identify common, modifiable risk factors in the population. Such knowledge is extensive for type 2 diabetes but limited for autoimmune forms of diabetes.

OBJECTIVE

This review aims at summarizing the limited literature on potential environmental (lifestyle) risk factors for LADA.

METHODS

A PubMed search identified 15 papers estimating the risk of LADA in relation to lifestyle. These were based on data from two population-based studies; one Swedish case-control study and one Norwegian cohort study.

RESULTS

Studies published to date indicate that the risk of LADA is associated with factors promoting insulin resistance and type 2 diabetes such as overweight, physical inactivity, smoking, low birth weight, sweetened beverage intake and moderate alcohol consumption (protective). Findings also indicate potential effects on autoimmunity exerted by intake of coffee (harmful) and fatty fish (protective). This supports the concept of LADA as being a hybrid form of diabetes with an etiology including factors associated with both insulin resistance and autoimmunity.

CONCLUSION

LADA may in part be preventable through the same lifestyle modifications as type 2 diabetes including weight loss, physical activity and smoking cessation. However, current knowledge is hampered by the small number of studies and the fact that they exclusively are based on Scandinavian populations. There is a great need for additional studies exploring the role of lifestyle factors in the development of LADA.

Association of cholesterol and lifestyle markers with type 1 diabetes incidence rates at a population level

Background

We investigated the hypotheses that mean population body mass index (BMI), systolic blood pressure (SBP), fasting plasma glucose (FPG), total cholesterol (TC) and the prevalence of type 2 diabetes (T2DM) are correlated with type 1 diabetes (T1DM) incidence rates.

Methods

Population-based mean incidence rates for T1DM in children aged ≤14 years participating in the World Health Organization Diabetes Mondial (DiaMond) project were compared with population mean values for BMI, SBP, TC and FPG, as well as prevalence rates for T2DM as reported by The Global Burden of Metabolic Risk Factors Chronic Diseases Collaborating Group, using Spearman's rank correlation and multiple regression analysis.

Results

The mean incidence rate for T1DM in boys was significantly correlated with country mean BMI, SBP and TC in men and mean TC in women, and negatively correlated with the country incidence of T2DM in either gender. We also found significant correlations between mean incidence rates of T1DM in girls and mean BMI, SBP and TC in men and mean TC in women. In multiple regression analyses, mean TC emerged as the sole significant predictor for T1DM in both boys (P < 0.001, adjusted R2 = 0.393) and girls (P < 0.001, adjusted R2 = 0.372).

Conclusion

Population mean total cholesterol is a significant predictor for country incidence of type 1 diabetes in both boys and girls. This association may fuel the rising incidence rates of type 1 diabetes reported in many countries.

Covariation of the incidence of type 1 diabetes with country characteristics available in public databases

BACKGROUND

The incidence of Type 1 Diabetes (T1D) in children varies dramatically between countries. Part of the explanation must be sought in environmental factors. Increasingly, public databases provide information on country-to-country environmental differences.

METHODS

Information on the incidence of T1D and country characteristics were searched for in the 194 World Health Organization (WHO) member countries. T1D incidence was extracted from a systematic literature review of all papers published between 1975 and 2014, including the 2013 update from the International Diabetes Federation. The information on country characteristics was searched in public databases. We considered all indicators with a plausible relation with T1D and those previously reported as correlated with T1D, and for which there was less than 5% missing values. This yielded 77 indicators. Four domains were explored: Climate and environment, Demography, Economy, and Health Conditions. Bonferroni correction to correct false discovery rate (FDR) was used in bivariate analyses. Stepwise multiple regressions, served to identify independent predictors of the geographical variation of T1D.

FINDINGS

T1D incidence was estimated for 80 WHO countries. Forty-one significant correlations between T1D and the selected indicators were found. Stepwise Multiple Linear Regressions performed in the four explored domains indicated that the percentages of variance explained by the indicators were respectively 35% for Climate and environment, 33% for Demography, 45% for Economy, and 46% for Health conditions, and 51% in the Final model, where all variables selected by domain were considered. Significant environmental predictors of the country-to-country variation of T1D incidence included UV radiation, number of mobile cellular subscriptions in the country, health expenditure per capita, hepatitis B immunization and mean body mass index (BMI).

CONCLUSIONS

The increasing availability of public databases providing information in all global environmental domains should allow new analyses to identify further geographical, behavioral, social and economic factors, or indicators that point to latent causal factors of T1D.

Impact of socioeconomic status and gender on glycaemic control, cardiovascular risk factors and diabetes complications in type 1 and 2 diabetes: a population based analysis from a Scottish region

AIMS

In this cross-sectional study, the aims were to investigate the association of the socioeconomic status and gender on the prevalence of type 1 and 2 diabetes, glycaemic control, cardiovascular risk factors plus the complications of diabetes in a population-based analysis in the county of Ayrshire and Arran, Scotland.

METHODS

Quality Outcome Framework data was obtained from General Practices in Ayrshire and Arran, Scotland (n=15,351 patients).

RESULTS

In type 1 diabetes, there was an increasing linear trend in HbA1c across deprivation levels (P<0.01). In type 1 diabetes, obesity in women (P<0.01) and increased non-fasting triglyceride levels in both men and women were associated with deprivation (P<0.05). In type 2 diabetes, there was a significant prevalence trend with deprivation for women (P<0.01) but not with glycaemic control (P=0.12). Smoking, ischaemic heart disease and neuropathy (P<0.01) were all associated with increasing deprivation with gender differences. In type 2 diabetes, reduced HDL cholesterol (P<0.01 both genders), and percentage of people on lipid lowering therapy (men P<0.05; women P<0.01) were associated with deprivation. Smoking, ischaemic heart disease, peripheral vascular disease and neuropathy plus foot ulcers (P<0.05) were all associated with increasing deprivation with gender differences.

CONCLUSIONS

Socioeconomic status and gender are associated with changes in glycaemic control and cardiovascular risk factors plus complication development in both type 1 and 2 diabetes. The mechanisms are unclear but follow-up of these patients should allow greater understanding.

Epidemiology of childhood Type 1 diabetes in Taiwan, 2003 to 2008

AIMS

To report the annual incidence rate and the socio-demographic and clinical characteristics of childhood Type 1 diabetes in Taiwan in the period 2003-2008.

METHODS

A total of 1306 incident cases of childhood (0-14 years) Type 1 diabetes were identified from Taiwan's National Health Insurance claim datasets from the period 2003-2008. The temporal trend of the incidence rate of Type 1 diabetes and the features of hospitalizations in the first year after diagnosis were investigated. The associations of patient characteristics, child population density and the urbanization level of the residential areas with the risk of Type 1 diabetes were assessed using Poisson regression analysis.

RESULTS

The annual incidence rate was stable, irrespective of age and gender, with a mean annual incidence rate of 5.3 per 100 000 children. Girls were more likely than boys to develop Type 1 diabetes (6.0 vs 4.7 per 100 000 children) and the incidence rate increased with age. There was no apparent geographic variation in the incidence rates. Despite the 60% decrease in the rate of admission (from 11.0 to 5.8%) over the study period, ketoacidosis remained the major diabetes complication leading to admission for childhood Type 1 diabetes. The multivariate analysis suggested that female gender and older age were significant predictors of the incidence of Type 1 diabetes, whereas the population density of children and the urbanization levels of the residential areas were not.

CONCLUSIONS

Girls and older children should receive particular attention when formulating preventive strategies targeting Type 1 diabetes. Additionally, clinicians should still carefully optimize the management of children with Type 1 diabetes to further reduce the occurrence of ketoacidosis.

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”.

Early life socioeconomic indicators and risk of type 1 diabetes in children and young adults

OBJECTIVE

To examine the potential role of 2 early-life socioeconomic indicators, parental education, and crowding index, on risk of type 1 diabetes (T1DM) in patients up to age 29 years to test heterogeneity by age at onset according to the hygiene hypothesis.

STUDY DESIGN

The study base was 330 950 individuals born from 1967 to 2006 who resided in the city of Turin at any time between 1984 and 2007. Data on their early life socioeconomic position were derived from the Turin Longitudinal Study; 414 incident cases of T1DM up to age 29 years were derived from the Turin T1DM registry.

RESULTS

Socioeconomic indicators had opposing effects on risk of T1DM in different age at onset subgroups. In a Poisson regression model that included both socioeconomic indicators, there was a 3-fold greater risk of T1DM (relative risk 2.91, 95% CI 0.99-8.56) in children age 0-3 years at diagnosis living in crowded houses. In the 4- to 14-year subgroup, a low parental educational level had a protective effect (relative risk 0.50, 95% CI 0.29-0.84), and the effect of crowding nearly disappeared. In the 15- to 29-year subgroup, neither crowding nor parental educational level was clearly associated with the incidence of T1DM.

CONCLUSIONS

We provide evidence of heterogeneity by age at onset of the association between early-life socioeconomic indicators and the risk of T1DM. This finding is consistent with the hypothesis that infectious agents in the perinatal period may increase the risk, whereas in the following years they may become protective factors (hygiene hypothesis).

Neighborhood context and incidence of type 1 diabetes: the SEARCH for Diabetes in Youth study

Findings regarding type 1 diabetes mellitus (T1DM) and neighborhood-level characteristics are mixed, with few US studies examining the influence of race/ethnicity. We conducted an ecologic study using SEARCH for Diabetes in Youth Study data to explore the association of neighborhood characteristics and T1DM incidence. 2002-2003 incident cases among youth at four SEARCH centers were included. Residential addresses were geocoded to US Census Tract. Standardized incidence ratios tended to increase with increasing education and median household income. Results from Poisson regression mixed models were similar and stable across race/ethnic groups and population density. Our study suggests a relationship of T1DM incidence with neighborhood-level socioeconomic status, independent of individual-level race/ethnic differences.

Low zinc in drinking water is associated with the risk of type 1 diabetes in children

AIM

To explore if drinking water may influence the development of type 1 diabetes in children, either via enterovirus spread via drinking water or quality of drinking water related to acidity or concentration of certain minerals.

METHODS

One hundred and forty-two families with a child with diabetes and who lived either in seven municipalities with a high annual diabetes incidence during 1977-2001 and in six municipalities with the lowest incidence during those 25 yr were asked to participate. Three hundred and seventy-three families in these communities were used as controls. The families filled a 200-mL plastic bottle with their tap drinking water and returned it by mail. The water samples were analyzed for pH, zinc, iron, nitrate, nitrite, nitrate-nitrogen and nitrite-nitrogen, and occurrence of enterovirus RNA.

RESULTS

Enterovirus RNA was not found in the tap water samples. The concentration of zinc, nitrate, and nitrate-nitrogen was lower in the municipalities with high incidence of type 1 diabetes. The water samples from families with a child with diabetes had lower concentration of zinc than water samples from control families.

CONCLUSION

Low zinc in drinking water is associated with the risk of developing type 1 diabetes during childhood. Enterovirus does not seem to be spread via drinking water in a country with modern water works.

High levels of education are associated with an increased risk of latent autoimmune diabetes in adults: results from the Nord-Trøndelag health study

OBJECTIVE

To investigate whether the risk for autoimmune diabetes in adults differs between socioeconomic groups and to compare such risk with that for type 2 diabetes.

RESEARCH DESIGN AND METHODS

The inhabitants of the Norwegian county of Nord-Trøndelag were investigated by questionnaires and clinical examinations on three occasions during 1984-2008. We used information from a subset consisting of 56,296 subjects (participating in at least two surveys), including 122 incident cases of autoimmune diabetes in adults (aged ≥35 and anti-GAD positive) and 1,555 cases of type 2 diabetes (aged ≥35 and anti-GAD negative). Hazard ratios (HRs) of diabetes associated with self-reported education and occupation were estimated by Cox proportional hazards models.

RESULTS

High levels of education (university versus primary school) were associated with an increased risk of autoimmune diabetes (HR 1.98 [95% CI 1.21-3.26]), after adjustment for BMI, lifestyle factors, and family history of diabetes. Case subjects with high levels of education had lower levels of C-peptide, tended to have higher levels of anti-GAD, and were more often treated with insulin. Conversely, these subjects had a reduced risk of type 2 diabetes (HR 0.69 [95% CI 0.57-0.82]), a risk that was partly explained by lower BMI and more physical activity (adjusted HR 0.89 [95% CI 0.74-1.06]).

CONCLUSIONS

High levels of education are associated with an increased risk of autoimmune diabetes in adults, a finding that may be mediated by effects on autoimmune activity. Because the association is not explained by traditional risk factors, other, currently unidentified, environmental factors are likely to be involved.

Clustering of cases of type 1 diabetes in high socioeconomic communes in Santiago de Chile: spatio-temporal and geographical analysis

The objective of this study was to describe spatial and space-time patterns of type 1 diabetes in children less than 15 years old, diagnosed between 2000 and 2005 with residence in the Metropolitan Region of Chile. Knox and Mantel tests were used to detect space-time interaction between cases. An ecological Bayesian model adjusted by socioeconomic factor and year was proposed to estimate the incidence by communes. Initially, there was no space-time interaction between cases, but there is evidence of clustering effect in urban areas of the region. The incidence rate for the overall study period was estimated by 6.18/100,000 (95% CI: 5.69-6.70), with a significant annual trend of 8.2% (P < 0.01). The geographical incidence could be explained by the human development index, as a socioeconomic factor. These results suggest that children living in communes with higher socioeconomic levels may be at higher risk of developing type 1 diabetes. Our findings support the hypothesis of an aetiological role of environmental factors in the onset of type 1 diabetes.

Cancer risk among patients hospitalized for Type 1 diabetes mellitus: a population-based cohort study in Sweden

AIMS

Type 1 diabetes mellitus (T1DM) is an autoimmune disease with potential mechanistic links to immune-related cancers. We aimed at examining the overall and specific cancer risks among hospitalized T1DM patients from the national registers in Sweden.

METHODS

A T1DM research cohort was created by identifying T1DM patients from the Hospital Discharge Register and linking them with the Cancer Registry. Standardized incidence ratios (SIRs) for subsequent cancers were calculated among patients with T1DM compared with those without T1DM.

RESULTS

Two hundred and fifty-eight cases were ascertained with subsequent cancers during the follow-up duration from 1964 to 2006, with an increased overall SIR of 1.17 (95% CI 1.04-1.33) among 24 052 T1DM patients identified at baseline. Significant excess was noted for gastric and skin (squamous cell carcinoma) cancers and for leukaemia. Increased risk of acute lymphatic leukaemia accounted for most of the variation of leukaemia risk (SIR = 5.31, 95% CI 3.32-8.05). Cancer risk varied with sex, age at first hospitalization and numbers of hospitalizations. The risk was higher in women compared with men and in those hospitalized for T1DM at age over 10 years compared with the younger patients. Higher risks were also found among those with more hospital visits.

CONCLUSION

By quantifying the variations of overall and site-specific cancer risks after T1DM, the current study provides novel associations between T1DM and subsequent cancers, the mechanisms of which remain to be established.

Temporal trends in incidence of Type 1 diabetes between 1986 and 2006 in Brazil

BACKGROUND

Scarce information is available about the variation in the incidence of Type 1 diabetes in the Brazilian population in the last decades.

AIM

The objective of this study was to assess the long-term trends (1986-2006) in the incidence of Type 1 diabetes in Bauru, São Paulo State, Brazil.

SUBJECTS AND METHODS

The annual incidence of Type 1 diabetes (per 100,000 per yr) from 1986 to 2006 was determined in children <or=14 yr of age, using the capture and recapture method.

RESULTS

A total of 176 cases were diagnosed in the study population. The overall incidence was 10.4/100,000 with a range of 2.82/100,000 in 1987 to 18.49/100,000 in 2002 representing a 6.56-fold increase within the same population. The estimated incidence, using the capture and recapture method varied from 2.82/100,000 per yr in 1987 to 27.20/100,000 per yr in 2002, representing a 9.6-fold variation. The global pattern of incidence variation was categorized as high (10-19.99/100,000 per yr), and very high (>or=20/100,000 per yr) in 71.43% of the study-years. Incidence was slightly higher among females, Caucasians, children in the 5-9 yr of age range and belonging to lower socio-economic classes. Most diagnoses were established during the colder months and/or with higher pluviometric indexes.

CONCLUSIONS

The incidence of Type 1 diabetes in children is increasing in Bauru, São Paulo State, Brazil, and the global pattern of incidence was classified as high or very high, mainly in the last 10 yr. All Brazilian regions should be involved in the study.

Defining and analyzing geoepidemiology and human autoimmunity

Autoimmune diseases cumulatively affect 5-10% of the industrial world population and are a significant cause of morbidity and mortality. In recent decades rates are rising worldwide, and autoimmunity can no longer be associated solely with the more developed "Western" countries. Geoepidemiology of autoimmune diseases portrays the burden of these illnesses across various regions and ethnic populations. Furthermore, Geoepidemiology may yield important clues to the genetic and triggering environmental mechanisms of autoimmunity. In this review we compiled and discuss in depth abundant geoepidemiological data pertaining to four major autoimmune conditions, namely type-1 diabetes mellitus, multiple sclerosis, autoimmune thyroid disease, and inflammatory bowel disease. The following key results manifested in this review: 1) Ethno-geographic gradients in autoimmune disease risk are attributable to a complex interplay of genetic and environmental pressures. 2) Industrial regions, particularly Northern Europe and North America, still exhibit the highest rates for most autoimmune diseases. 3) Methods particularly useful in demonstrating the significant influence of genetic and environmental factors include comparative ethnic differences studies, migration studies, and recognition of 'hotspots'. 4) Key environmental determinants of geographical differences include diminished ultraviolet radiation exposure, Western or affluence-related lifestyle, infection exposure, environmental pollutants, nutritional factors and disease-specific precipitants (e.g., iodine exposure).