Incidence of IDDM in Montreal by ethnic group and by social class and comparisons with ethnic groups living elsewhere

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.

Clinical profile at diagnosis with youth-onset type 1 and type 2 diabetes in two pediatric diabetes registries: SEARCH (United States) and YDR (India)

BACKGROUND

Over the last decades, diabetes in youth has increased in both India and the United States, along with the burden of long-term complications and healthcare costs. However, there are limited standardized population-based data in contemporary youth cohorts for comparison of clinical and demographic characteristics of diabetes for both type 1 (T1D) and type 2 (T2D).

METHODS

In partnership, we harmonized demographic and clinical data from the SEARCH for Diabetes in Youth (SEARCH) registry in the United States and the Registry of People with Diabetes with Youth Age at Onset (YDR) in India to the structure and terminology of the Observational Medical Outcomes Partnership Common Data Model. Data were from youth with T1D and T2D, aged <20 years and newly diagnosed between 2006 and 2010. We compared key characteristics across registries using χ² tests and t-tests.

RESULTS

In total, there were 9650 youth with T1D and 2406 youth with T2D from 2006 to 2012. SEARCH youth were diagnosed at younger ages than YDR youth for T1D and T2D (10.0 vs 10.5 years, P < .001 and 14.7 vs 16.1 years, P < .001, respectively). For T2D, SEARCH had a higher proportion of females and significantly lower proportion of youth of high socioeconomic status compared to YDR. For T1D and T2D, SEARCH youth had higher BMI, lower blood pressure, and lower A1c compared to YDR youth.

CONCLUSIONS

These data offer insights into the demographic and clinical characteristics of diabetes in youth across the two countries. Further research is needed to better understand why these differences exist.

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 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.

Socioeconomic conditions and type 1 diabetes in childhood in North Rhine-Westphalia, Germany

AIMS/HYPOTHESIS

The aim of the study was to investigate the relationships between childhood type 1 diabetes and socioeconomic conditions, which might provide clues to the aetiology of the disease.

MATERIALS AND METHODS

In an ecological study, we investigated the relationships between socioeconomic conditions and the incidence of type 1 diabetes incidence among children aged 0-14 years in North Rhine-Westphalia (NRW), Germany, between 1996 and 2000 at the level of the 33 districts. Incidence data were obtained from the population-based NRW diabetes register and regional socioeconomic data from official statistics. Associations were assessed by Poisson regression models and Bayesian conditionally autoregressive regression models (CAR).

RESULTS

In simple Poisson regression, population density, proportion of non-German nationals in the population, measures of income, education and professional training, and deprivation scores were significantly associated with diabetes risk (p < 0.01). An increase of about one interquartile range (IQR) in population density, proportion of non-German nationals or household income was associated with a 9-12% decrease in diabetes incidence. A rise of about one IQR in income ratio, measures of education and professional training, or in deprivation score (high values correspond to high deprivation) was associated with an 8-12% incidence increase. There was a significantly 'linear' increasing incidence trend across five deprivation classes (relative risk: 1.06; 95% CI: 1.03-1.09). All associations were confirmed when overdispersion and spatial autocorrelation were accounted for in Poisson and CAR models.

CONCLUSIONS/INTERPRETATIONS

The results raise the possibility that the risk for type 1 diabetes is higher for children living in socially deprived and less densely populated areas. Subsequent investigations are necessary to verify the observed ecological relations at the individual level and to identify the causal factors behind the socioeconomic indicators.

Incidence of type 1 diabetes in Philadelphia is higher in black than white children from 1995 to 1999: epidemic or misclassification?

OBJECTIVE

To determine the epidemiology of type 1 diabetes in children in Philadelphia, Pennsylvania, from 1995 through 1999 and compare these data with previous cohorts.

RESEARCH DESIGN AND METHODS

This is a report of a retrospective population-based registry maintained since 1985. Hospital records meeting the following criteria were reviewed: newly diagnosed type 1 diabetes, age 0-14 years, residing in Philadelphia at the time of diagnosis, and diagnosed from 1 January 1995 to 31 December 1999. The secondary source of validation was the School District of Philadelphia. Incidence rates by race and age were compared with 1985-1989 and 1990-1994 cohorts.

RESULTS

A total of 234 case subjects were identified, and the registry was determined to be 96% complete. The overall age-adjusted incidence rate in Philadelphia was 14.8 per 100,000/year. Incidence rates in Hispanic children (15.5 per 100,000/year) and white children (12.8 per 100,000/year) have been relatively stable over 15 years. The incidence in black children (15.2 per 100,000/year), however, has increased dramatically, rising 64% in children 5-9 years of age (14.9 per 100,000/year) and 37% in the 10- to 14-year age-group (26.9 per 100,000/year).

CONCLUSIONS

The overall incidence of type 1 diabetes in Philadelphia is increasing and is similar to other U.S. registries. These are the first data reporting a higher incidence in black children in a registry of children 0-14 years of age. The etiology of the marked increase in incidence in the black population is unknown and underscores the need to establish type 1 diabetes as a reportable disease, so that environmental risk factors may be thoroughly investigated.

Independent effects of socioeconomic status and place of residence on the incidence of childhood type 1 diabetes in Western Australia

OBJECTIVE

To analyze the incidence of type 1 diabetes in 0- to 14-year olds in Western Australia, from 1985 to 2002, by region and socioeconomic status.

METHODS

Primary case ascertainment was from the prospective population-based Western Australian Diabetes Register, and secondary case ascertainment was from the Western Australian Hospital Morbidity Data System. The address at diagnosis was used to categorize cases into urban, rural and remote areas and into five socioeconomic groups using the Index of Relative Socioeconomic Disadvantage. Denominator data were obtained from the Australian Bureau of Statistics. Poisson regression was used to analyze the incidence rates by area and socioeconomic status.

RESULTS

There were a total of 1143 cases (904 urban, 190 rural and 49 remote). Case ascertainment was estimated to be 99.8% complete. The mean annual age-standardized incidence from 1985 to 2002 was 18.1 per 100,000 person years in urban (95% CI: 16.3-19.9), 14.3 per 100,000 in rural (95% CI: 11.4-7.3) and 8.0 per 100,000 in remote areas (95% CI: 5.8-10.3). The incidence was significantly higher in urban compared with rural (rate ratio 1.27, p = 0.001) and remote (rate ratio 2.28, p < 0.001) areas. The incidence increased with higher socioeconomic status. The incidence in the highest socioeconomic group was 56% greater than the lowest socioeconomic group (rate ratio 1.56, p < 0.001). These differences in incidence by socioeconomic status and region were independent of each other.

CONCLUSIONS

Higher socioeconomic status and residence in the urban area are independently associated with an increased risk of childhood type 1 diabetes in Western Australia.

Socio-economic characteristics in children with coeliac disease

AIM

To study the relationship between socio-economic factors and coeliac disease.

METHODS

This study was part of a prospective cohort study of 16 286 children born from 1 October 1997-1 October 1999 (the ABIS study; All Babies in Southeast Sweden). Eight paediatric departments recorded all children with coeliac disease in southeast Sweden. Coeliac disease was confirmed through biopsy. Socio-economic characteristics (maternal employment, civil status, whether parents were born in Sweden, parental education, place of living before pregnancy and during pregnancy, crowded living), infant sex, previous siblings, parental age and maternal alcohol consumption during pregnancy were analysed using logistic regression. All data, except for those related to diagnosis of coeliac disease, were obtained through a questionnaire distributed at birth.

RESULTS

Coeliac disease in the offspring was less common among mothers who had worked < 3 mo during pregnancy (odds ratio, OR = 0.29; 95% CI: 0.09-0.94; p = 0.039). This risk decrease remained after adjustment for confounders (adjusted OR = 0.28; 95% CI: 0.09-0.92; p = 0.035). No other socio-economic factor was related to coeliac disease.

CONCLUSION

This study indicates that most socio-economic factors are probably of little importance to the development of coeliac disease.

Genetic epidemiology of type 1 diabetes

Family and twin studies indicate that a substantial fraction of susceptibility to type 1 diabetes is attributable to genetic factors. These and other epidemiologic studies also implicate environmental factors as important triggers. Although the specific environmental factors that contribute to immune-mediated diabetes remain unknown, several of the relevant genetic factors have been identified using two main approaches: genome-wide linkage analysis and candidate gene association studies. This article reviews the epidemiology of type 1 diabetes, the relative merits of linkage and association studies, and the results achieved so far using these two approaches. Prospects for the future of type 1 diabetes genetics research are considered.

Incidence of type 1 diabetes in Lithuanians aged 0-39 years varies by the urban-rural setting, and the time change differs for men and women during 1991-2000

OBJECTIVE

Type 1 diabetes has been associated with factors related to welfare and social class. During the past decade, Lithuania has experienced a transition period, leading to dramatic changes in the socioeconomic structure of the society.

RESEARCH DESIGN AND METHODS

Incidence in the group aged 0-39 years by urban-rural setting (cities >100000 inhabitants, towns, and rural areas), period (1991-1995 and 1996-2000), age, and sex were studied using Poisson regression.

RESULTS

The age- and sex-standardized incidence per 100000 inhabitants per year was higher in men aged 0-39 years than in women (9.5 and 6.9, respectively, incidence rate ratio [IRR] = 1.39, P < 0.001). Incidence was lower in rural areas than in towns and cities (7.1, 9.0, and 8.8, respectively, P < 0.001). The urban-rural differences in incidence were most marked among children aged 0-9 years. From 1991-1995 to 1996-2000, the overall incidence increased from 8.7 to 10.5 (IRR = 1.22, P = 0.001) in men and from 6.2 to 7.8 (IRR = 1.25, P = 0.002) in women. For men, the increase over time occurred predominantly in the cities, from 8.4 to 11.8 (IRR = 1.40, P < 0.001), and in the older age-groups. In contrast, for women, the incidence increased more in small towns and rural areas, from 5.8 to 7.7 (IRR = 1.33, P = 0.003), and in the younger age-groups.

CONCLUSIONS

The incidence of type 1 diabetes in Lithuania differs depending on the urban-rural setting, and the pattern of change over time differs between the sexes, both by urban-rural setting and age-group. The findings support the theory that lifestyle-related factors connected to socioeconomic status are important for the occurrence of type 1 diabetes.

Molecular aspects of type 1 diabetes

Type 1 diabetes is a T cell mediated autoimmune disease, characterised by the selective destruction of pancreatic beta cells, and susceptibility is determined by a combination of genetic and environmental factors. The environmental agents implicated include viruses and dietary factors, although none has yet been shown to be directly responsible for triggering beta cell autoimmunity. The genetic factors that influence disease risk have been subjected to more intensive study and two gene regions of major importance have been identified: the human leucocyte antigen locus and the insulin gene. This review will focus on the mechanisms by which these genes might influence the risk of developing type 1 diabetes.

Social disadvantage, family composition, and diabetes mellitus: prevalence and outcome

OBJECTIVE

To investigate the relation between social disadvantage and family composition on diabetes prevalence and diabetes care outcome.

DESIGN

Retrospective audit in the south west of England of 801 children with diabetes mellitus.

MAIN OUTCOME MEASURES

Prevalence of diabetes in relation to the Townsend index. Admissions to hospital with diabetes related problems, glycated haemoglobin, time spent in hospital, outpatient attendance rates.

RESULTS

There was no association between social status and diabetes prevalence. Social deprivation increased the likelihood of admission for hypoglycaemia. Children living with a single parent were more likely to be admitted to hospital with a diabetes related problem and stay in hospital longer. Having either a parent with diabetes or a single parent increased the rates of clinic non-attendance. No association was identified between medium term diabetes control and either social disadvantage or single parent status.

CONCLUSIONS

Social disadvantage has no effect on diabetes prevalence and little on diabetes outcome in childhood. Family structure and parental diabetes have adverse effects on some aspects of diabetes outcome.

Epidemiology and estimated population burden of selected autoimmune diseases in the United States

Autoimmune diseases cause significant and chronic morbidity and disability. The actual number of persons in the United States that are affected by autoimmune diseases and the resultant magnitude of their impact on the public's health are limited to a few specific diseases. In order to understand the clinical, public health and economic importance of these diseases it is necessary to have estimates of incidence and prevalence rates in the population. In this analysis, we estimate the number of persons affected by 24 autoimmune diseases in the United States by applying mean weighted prevalence and incidence rates obtained from published articles to U. S. Census data. The study was restricted to 24 autoimmune predefined diseases for which there was direct or indirect evidence for autoimmune pathogenesis. Subsequently, we used computerized search software and ancestry searching (bibliographies) to conduct a comprehensive search of articles published from 1965 to the present. Eligible studies included those which adhered to standard disease definitions and which included population-based estimates of incidence or prevalence rates. Mean weighted incidence and prevalence rates were calculated from eligible published studies with greater weight proportionately given to larger studies. The mean rates were then applied to the U.S. Census population figures to estimate the number of persons currently afflicted with each disease and the number of new cases occurring each year in the United States. Only U.S. and European studies were used to estimate prevalence and incidence rates when there were at least six eligible studies available for a disease. When there were fewer than six studies, all available studies were included, regardless of country of origin. The number of eligible incidence and prevalence studies found in the literature varied considerably between the 24 autoimmune diseases selected. The largest number of eligible prevalence studies were conducted on multiple sclerosis (MS), rheumatoid arthritis, and systemic lupus erythematosus (SLE) (>/=23), followed by insulin-dependent diabetes (IDDM), myasthenia gravis, primary biliary cirrhosis, and scleroderma (>/=7). There were only one to four eligible studies done on 11 other diseases, and no prevalence studies on 6 diseases. Incidence studies were less frequent but the largest number of studies were conducted on IDDM (n = 37) and MS (n = 28), followed by Graves' disease/hyperthyroidism, glomerulonephritis, primary biliary cirrhosis, rheumatic fever, rheumatoid arthritis, scleroderma, and SLE (>/=9). On the other 11 diseases, there were one to six eligible studies, and no studies on 5 diseases. There were no eligible incidence or prevalence studies on Goodpasture's syndrome, idiopathic thrombocytopenia purpura, or relapsing polychondritis. Overall we estimate that 8,511,845 persons in the United States or approximately 1 in 31 Americans are currently afflicted with one of these autoimmune diseases. The diseases with the highest prevalence rates were Graves'/hyperthyroidism, IDDM, pernicious anemia, rheumatoid arthritis, thyroiditis, and vitiligo, comprising an estimated 7,939, 280 people or 93% of the total number estimated. Glomerulonephritis, MS, and SLE added an estimated 323,232 people. The prevalence of the other diseases reviewed were rare, less than 5.14/100,000. Most diseases were more common in women. From the incidence data we estimate that 237,203 Americans will develop an autoimmune disease in 1996 and that approximately 1,186,015 new cases of these autoimmune diseases occur in the United States every 5 years. Women were at 2.7 times greater risk than men to acquire an autoimmune disease. After reviewing the medical literature for incidence and prevalence rates of 24 autoimmune diseases, we conclude that many autoimmune diseases are infrequently studied by epidemiologists. As a result the total burden of disease may be an underestimate. (ABSTRACT TRUNCATED)

Dramatic increase in incidence of insulin dependent diabetes mellitus in Western Australia

OBJECTIVES

To document and suggest possible reasons for a dramatic increase in the incidence of insulin dependent diabetes mellitus (IDDM) in Western Australia in 1992.

PATIENTS

Children aged 0-14 years with IDDM diagnosed in Western Australia from 1985 to 1992 inclusive.

DESIGN

A population-based register in Western Australia, using name-identified data from two separate ascertainment sources, provided numerator data. Denominator data were estimated from census figures collected in 1986 and 1991 by the Australian Bureau of Statistics. The completeness of case ascertainment was estimated by the capture-recapture method.

RESULTS

Case ascertainment for 1985-1992 was estimated as 99.6% complete. Between 1985 and 1991 the incidence of IDDM in the 0-14 year age group varied between 11.8 and 15.5 per 100,000 person-years without a significant increase. In 1992, however, based on the previous seven years, 52 cases would have been expected but 84 cases were observed, an incidence of 22.2 per 100,000 person-years. The increase in incidence occurred across all age groups and in both sexes. Place of residence at diagnosis, the prevalence of islet cell antibody positivity at diagnosis and the proportion of new cases with a first degree relative with IDDM were no different in 1992 than in preceding years.

CONCLUSION

This is the first report of a significant increase in the incidence of IDDM in Australia. It appears to be a period, rather than a cohort, effect and provides further evidence for environmental antigens as disease triggers.

Family characteristics and insulin dependent diabetes

During the calendar year of 1988 a survey of new cases of insulin dependent diabetes mellitus (IDDM) in children under the age of 15 years in the British Isles was conducted. After cases had been confirmed and permission obtained to contact the families, postal questionnaires were sent to the parents of children diagnosed in England, Wales, Northern Ireland, and the Republic of Ireland. Children who developed diabetes were significantly more likely to be heavier at birth in comparison with national reference data. The diabetic children were less likely to have been breast fed, and there were more children than expected whose fathers were in nonmanual occupations. Where there was a first degree relative with IDDM there were positive correlations between the age at diagnosis of the index cases and that of their diabetic fathers and their diabetic siblings, but not their diabetic mothers. A higher proportion of children than expected who were diagnosed under the age of 5 years had fathers with IDDM. Characteristics of family members associated with IDDM in children that might provide pointers to the aetiology of the disease include heavier birth weight, method of infant feeding, the age at onset of IDDM in affected fathers and affected siblings, and the family lifestyle as defined by social class of the father.

The interface between epidemiology and molecular biology in the search for the causes of insulin-dependent diabetes mellitus

Epidemiological techniques have been utilized to accumulate new knowledge about insulin-dependent diabetes mellitus (IDDM), leading to important insights into the disease process and the alteration of these mechanisms when viewed from a geographic or population base. More recently, highly powerful and sophisticated techniques of molecular biology have been added to the research arsenal, extending the knowledge on the genetic basis for IDDM and the probable environmental factors involved. The development and growth of the new discipline of epidemiological genetics promises exciting new developments for the future of our field as well as that of other major medical problems having a genetic base, but significantly influenced by environmental factors. This review stresses the importance of carefully validated diabetes registries in the study of the epidemiology of IDDM. The Children's Hospital of Pittsburgh and the University of Pittsburgh Medical Center have spear-headed the development of such registries, worldwide. The first international meeting on IDDM epidemiology in 1983 gave as a result, i.e., the finding that there were truly remarkable differences in the risk of developing IDDM depending upon the geographic location of the individual. Later collaborative work via the Diabetes Epidemiology Research International (DERI) group has confirmed the previous finding and added the description of secular trends and epidemics of IDDM. It is remarkable that the incidence rate of IDDM in children below 15 years vary from 1/100,000/yr in the Orient to 35/100,000/yr in Finland. The epidemiological approach in the study of IDDM has also stimulated research into the various facets of the etiology of the disease, genetic factors, autoimmune mechanisms and environmental factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin dependent diabetes in childhood and material deprivation in northern England, 1977-86

OBJECTIVE

To determine the incidence of insulin dependent diabetes in the Northern region of England in children less than 16 years old in the period 1977 to 1986 and to relate the incidence data to an index of deprivation.

DESIGN

Retrospective analysis of hospital case records identified from the regional health authority's computer; validation of the primary source with hospital clinic registers and community paediatric registers.

SETTING

Northern region, excluding South Cumbria District Health Authority (659,300 children under 16 in 1981).

PATIENTS

All children diagnosed with insulin dependent diabetes before the age of 16 and resident in the region at time of diagnosis.

MAIN OUTCOME MEASURES

Incidence rates for the 10 year period and analysis of incidence rates within categories of deprivation.

RESULTS

919 incident cases were identified. The validation procedure covered 54% of all cases identified and gave 95% completeness of ascertainment. The average annual incidence over the 10 year period was 14.8/100,000 for girls and 13.4/100,000 for boys. The annual incidence for the most and least deprived areas of the region was 18.7/100,000 (95% confidence interval 16.2 to 21.5) for boys and 7/100,000 (5.6 to 8.8) for girls. There was a highly significant trend (p less than 0.001) of decreasing incidence with decreasing level of deprivation.

CONCLUSIONS

In the north of England the incidence of childhood diabetes is related to material deprivation.

The epidemiology of diabetes in childhood with special reference to the Orient: implications for mechanism of beta cell damage

Epidemiologic studies are providing important new insights into the etiology and clinical course of IDDM as well as providing critically needed data on the magnitude of the problem in different parts of the world. The development of national IDDM registries have documented extraordinary differences in diabetes incidence and prevalence, with the highest incidence figures in Finland (greater than 30/100,000/yr) and the lowest in the Orient with Korea reporting incidence rates below 1 and Japan between 1.0-2.4/100,000/yr. The great geographic variation in expression of diabetes in childhood is strongly supportive of environmental factors playing a major role in the etiology of disease. Our studies document a linear correlation between IDDM incidence and distance from the equator and a similar but inverse correlation with mean annual environmental temperature. Other workers find a direct correlation with dairy product consumption. Factors that may play a role in beta cell damage include viral infections, environmental toxins, nutrients and stress factors. Because of the low incidence of IDDM among children living in Asia it is most important to expand the current national registries in the Asian countries and begin a careful study of the environmental differences within Asian countries as well as comparison of studies between countries with very high incidence rates and those with the lowest rates.