Ethnic differences in the incidence of childhood IDDM in Israel (1965-1993). Marked increase since 1985, especially in Yemenite Jews

Hypothesis: Viral infections of pregnant women may be early triggers of childhood type 1 diabetes and other autoimmune disease

Children and adolescents with early onset autoimmune diseases have a different seasonality of month of birth than the general population. This pattern is consistent with an infection during pregnancy affecting the fetus or an infection immediately after birth that act as early triggers of the autoimmune diseases. We present data supporting the use of Rotavirus vaccinations in the reduction of incidence of childhood T1D and propose further investigations into whether other anti-virus vaccinations may reduce the burden of other autoimmune diseases such as multiple sclerosis, atopic dermatitis, psoriasis and subtypes of rheumatoid arthritis, Hashimoto thyroiditis.

Incidence and seasonality of type 1 diabetes: a population-based 3-year cohort study using the National Database in Japan

INTRODUCTION

To investigate the incidence of type 1 diabetes by age group (0-19, 20-39, 40-59, ≥60 years) in Japan and whether there is seasonality in this incidence.

RESEARCH DESIGN AND METHODS

The incidence of type 1 diabetes from September 2014 to August 2017 was estimated using 2013-2018 data from the National Database of Health Insurance Claims and Specific Health Check-ups of Japan. The incidence rate was analyzed using Tango's Index and the self-controlled case series method.

RESULTS

Overall, 10 400 of the 79 175 553 included individuals were diagnosed with type 1 diabetes. The incidence of type 1 diabetes from September 2014 to August 2017 was 4.42/100 000 person-years. The incidence rates for men aged 0-19, 20-39, 40-59, and ≥60 years were 3.94, 5.57, 5.70, and 3.48, respectively. Among women, the incidence rates for the same age ranges were 5.22, 4.83, 4.99, and 3.31, respectively. Tango's index showed that the incidence rate of type 1 diabetes was significantly associated with seasons among those aged 0-19 years. Further, the self-controlled case series method showed a significant interaction between age and season, with the incidence of type 1 diabetes being higher in spring for patients younger than 20 years of age.

CONCLUSIONS

In Japan, men aged 40-59 years and women aged 0-19 years are the groups with the highest incidence of type 1 diabetes. Further, the incidence of younger-onset diabetes in Japan was higher in spring (from March to May).

Newborn BCG vaccination complemented by boosting correlates better with reduced juvenile diabetes in females, than vaccination alone

Type 1 diabetes (T1D), like other autoimmune diseases, is on the rise since the second half of the 20th century. Hypothetically this has been ascribed to restricted exposure to microbial diversity due to advanced hygienic practices accompanying modernization, and increasing prosperity in urban versus rural habitats. The autoimmune animal model of T1D, inhibited by Bacillus Calmette Guerine (BCG), motivated testing the impact of BCG on T1D incidence in humans. Several epidemiological analyses, short of one, failed to demonstrate a protective effect of BCG against T1D. The present retrospective analysis of two data sets reevaluates the hypothetic inhibitory effect of BCG on human T1D. Reassessment of data from a Swedish study reveals that a single BCG vaccination provided a small but significant protection against T1D. A second data set of T1D prevalence/1000 Israeli military conscripts, from a doctoral thesis presenting 17 birth cohorts at age 17 is evaluated against the national schedule of vaccination related to years of birth. To correct for the annual increasing T1D trend the mean urbanization (census) rate was set as an annual moving average and factored into the prevalence (T1D/1000) of respective birth cohorts. Three groups of cohorts corresponding to BCG vaccination are presently identified; Group A corresponds to the years in which newborns were vaccinated and boosted if necessary, at age 12. Group B corresponds to the period when boosting was discontinued. Group C corresponds to years when newborn BCG vaccination was discontinued. T1D (only in females) was slightly but significantly lower in group B (n = 5 cohorts) versus C (n = 8 cohorts, p = 0.0475, by Mann Whitney U test). T1D in group A (n = 4 cohorts) was lower than in group B (p = 0.02). This analysis supports the hypothesis that in human females postnatal BCG vaccination, reinforced by boosting, has a protective impact on T1D being superior to omitted boosting, which in its turn is still better than stopping vaccination altogether. This analysis further suggests that upon advanced modernization the BCG vaccine compensates for reduced exposure to microbial diversity early in life.

Increasing incidence of type 1 diabetes among Hong Kong children and adolescents: The Hong Kong Childhood Diabetes Registry 2008 to 2017

OBJECTIVE

The incidence of childhood-onset type 1 diabetes (T1D) has been reported to be rising but there is also evidence that it has been attenuated in recent years. We described the time trends and the incidence of T1D in children in Hong Kong from 2008 to 2017 and compared with the previous local registry in 1997 to 2007.

METHODS

Data were extracted from the Hong Kong Childhood Diabetes Registry, which was established in 2016. It consists of a retrospective registry (including all childhood diabetes diagnosed in 2008 to 2015) and a prospective registry (including all T1D children diagnosed from 2016 onwards). All T1D children diagnosed at the age of less than 18 years from 1 January 2008 to 31 December 2017 and managed in the public system were included in this study.

RESULTS

For the incident years in the 2008 to 2017 period, a total of 498 children with T1D was identified. The crude incidence rate was 4.3 per 100 000 person/year (95% confidence interval 3.96-4.72), which was much higher than the last registry of 2.2 per 100 000 persons/year. Using general linear model, the increment is statistically significant (P = .02). When compared to the last registry, the rate of increment had attenuated, with annual increment in crude incidence in the two periods for T1D <15 years changing from 4.3% to 3.5% (P = .02).

CONCLUSIONS

The incidence of T1D children increased significantly in the past two decades in Hong Kong, but the rate of increase had attenuated in recent years.

Prevalence and incidence of type 1 diabetes in the world: a systematic review and meta-analysis

Background: Diabetes is referred to a group of diseases characterized by high glucose levels in blood. It is caused by a deficiency in the production or function of insulin or both, which can occur because of different reasons, resulting in protein and lipid metabolic disorders. The aim of this study was to systematically review the prevalence and incidence of type 1 diabetes in the world. Methods: A systematic search of resources was conducted to investigate the prevalence and incidence of type 1 diabetes in the world. The databases of Medline (via PubMed and Ovid),ProQuest, Scopus, and Web of Science from January 1980 to September 2019 were searched to locate English articles. The located articles were screened in multiple levels of title, abstract,and full-text and final studies that met the inclusion criteria were retrieved and included in the study. Results: From 1202 located articles, 193 studies were included in this systematic review. The results of meta-analysis showed that the incidence of type 1 diabetes was 15 per 100,000 people and the prevalence was 9.5% (95% CI: 0.07 to 0.12) in the world, which was statistically significant. Conclusion: According to the results, the incidence and prevalence of type 1 diabetes are increasing in the world. As a result, insulin will be difficult to access and afford, especially in underdeveloped and developing countries.

Racial and ethnic differences in cardiovascular disease and outcome in type 1 diabetes patients

INTRODUCTION

Type 1 diabetes mellitus (T1DM) has increased dramatically over the last two decades with global variation greater than 350-fold difference reflecting the ethnic, racial, and geographical variation. Diabetic patients remain at a higher risk of cardiovascular mortality than those without diabetes. Therefore, it is vital for clinicians to have in-depth knowledge of T1DM statistics and their impact on people health and health resources.

AREAS COVERED

This review will cover the epidemiologic characteristics of T1DM and the influence of race, ethnicity, and geographical variation on the incidence and the outcome. The minority populations health disparities in the clinical presentation and outcomes among youth with T1DM, the long-term glycemic control patterns in racially and ethnically diverse youth, and the long-term influence of these factors on cardiovascular outcomes will be elucidated. The PubMed database was searched using the terms: T1DM ± incidence, Race, ethnicity, and Genetic.

EXPERT OPINION

Understanding the epidemiological characteristics of T1DM including race, ethnicity and the genetic predisposition will help to develop guidelines target these higher risk patients of an unfavorable outcome. Further research and interventional strategies to identify infants at genetic risk of T1DM may help to prevent, stop or retard the destructive autoimmune process leading to T1DM.

Climates on incidence of childhood type 1 diabetes mellitus in 72 countries

We are aimed to systematically assess the worldwide trend in incidence of childhood type 1 diabetes mellitus (CT1DM) from 1965 to 2012 and to discuss whether climate affect incidence of CT1DM. We searched the relevant literatures in detail to judge the effect of different climates on incidence of CT1DM. The climates included Mediterranean, monsoon, oceanic, continental, savanna, and rainforest. According to different climates, we further researched relevant factor such as sunshine durations and latitudes. The overall incidence of CT1DM in 72 countries was 11.43 (95% CI 10.31–12.55) per 100,000 children/yr. The incidence of CT1DM in Oceanic climate [10.56 (8.69–12.42)] is highest compared with other climates; the incidence in 40°–66°34′N/S [14.71 (12.30–17.29)] is higher than other latitude groups; the incidence in sunshine durations with 3–4 hours per day [15.17 (11.14–19.20)] is highest compared with other two groups; the incidence of CT1DM from 2000 to 2012 [19.58 (14.55–24.60)] is higher than other periods; all p < 0.01. Incidence of CT1DM was increasing from 1965 to 2012, but incidence in Oceanic climate is higher than other climates. Furthermore, it is higher in centers with higher latitude and lower sunshine durations. The climates might play a key role in inducing CT1DM.

Incidence and prevalence of childhood-onset Type 1 diabetes in Japan: the T1D study

AIMS

A majority of children with Type 1 diabetes in Japan are registered with the government-subsidized Specified Pediatric Chronic Disease Treatment Research Projects (SPCDTRP). In this study, the incidence and prevalence of childhood-onset (< 15 years) Type 1 diabetes in Japan were estimated by drawing on SPCDTRP data.

METHODS

Data available for 2005-2012 from the SPCDTRP and Statistics Bureau, Ministry of Internal Affairs and Communications were used to estimate the incidence of Type 1 diabetes for 2005-2010, adjusted to cover those registered within 3 years of disease onset and stratified by sex, age at onset and period of onset.

RESULTS

The incidence of Type 1 diabetes for 2005-2010 was 2.25/100,000 persons [95% confidence intervals (95% CI), 2.14-2.36] (boys: 1.91, 95% CI, 1.83-1.98; girls: 2.52, 95% CI, 2.34-2.69), with that for the age brackets 0-4, 5-9 and 10-14 years being 1.48 (95% CI, 1.29-1.66), 2.27 (95% CI, 2.08-2.47) and 3.00 (95% CI, 2.74-3.25), respectively. The onset of disease was shown to peak at age 13 among boys (3.28, 95% CI, 3.02-3.55) and at age 10 among girls (3.28, 95% CI, 3.02-3.55). The peak periods of disease onset were April/May and December. The number of children aged < 15 years with Type 1 diabetes for 2005-2012 was estimated to be 2326 (95% CI, 2202-2450) with the prevalence estimated as 13.53/100,000 persons (95% CI, 12.63-14.43).

CONCLUSIONS

Study findings demonstrated no increase in the incidence of Type 1 diabetes, although suggesting, in agreement with earlier reports, that the onset of disease peaks in adolescence with a female predominance. In addition, the incidence of childhood-onset diabetes exhibited an annual bimodal pattern in this study.

Increasing incidence of type 1 diabetes between 1986 and 2015 in Bauru, Brazil

AIMS

To assess temporal trends in the incidence of type 1 diabetes in Bauru, São Paulo State, Brazil from 1986 to 2015.

RESEARCH DESIGN AND METHODS

The yearly incidence of type 1 diabetes (per 100,000/yr) from 1986 to 2015 was determined in children ≤14yr of age, using individual case notification and the capture and recapture method.

RESULTS

During thirty years (1986-2015), 302 cases were diagnosed in our population. The overall incidence was of 12.8/100,000 (95% CI: 11.2-14.4), ranging from 2.8/100,000 in 1987 to 25.6/100,000 in 2013 with a 9.1-fold variation. It was non-significantly higher in girls [13.7 (95% CI: 11.4-16.1)] than in boys [12.0 (95% CI: 9.8-14.2)] (p=0.48) and significantly higher in the 5-9yr [14.6 (95% CI: 11.8-17.4)] and 10-14yr [15.8 (95% CI: 12.7-18.8)] age ranges compared to the 0-4yr [8.1 (95% CI: 6.0-10.2)] age range (p<0.001). The majority of diagnoses were made in colder months. The patterns of incidence were very high and high in 80.0% of the study-years.

CONCLUSIONS

The incidence of type1 diabetes in children ≤14yr has increased in Bauru, Brazil, in the last thirty years, in approximately 3.1% annually, with an absolute crude increase of 2.5-fold. These findings pose Brazil as a country with high incidence of type 1 diabetes. All Brazilian regions should be enrolled in future studies to determine the factors that contribute to the predisposition to type 1 diabetes in our population and to the steep rise in its incidence.

Association of HLA-DQA1 and -DQB1 alleles with type I diabetes in Arabs: a meta-analyses

This study aimed at assessing the nature and significance of associations between various alleles of HLA-DQA1, HLA-DQB1, and type I diabetes (T1D) in Arab populations. Evidence from literature (published before 20 April 2015) was amassed and analysed through multiple meta-analyses, which yielded effect summary odds ratios and 95% confidence intervals for 24 alleles and 4 haplotypes. A total of 1273 cases and 1747 controls from 16 studies were analysed. High levels of significance were obtained to support higher T1D risk when harbouring DQA1*03:01. The alleles DQB1*02:01 and *03:02 and the haplotypes DR3 and DR4 were significant risk factors, albeit with high publication heterogeneity. The protective effects of DQA1*01:01, DQB1*05:03, *06:02, *06:03, and *06:04 were robustly suggested by all indicators of meta-analyses. The haplotypes DR7 and DR11 were strongly suggested to be protective in Arabs. A relatively small number of studies have emerged from Arab countries, mostly with inadequate power on an individual basis. This study fills the gap by providing significant size effect of human leukocyte antigen (HLA) alleles and completes the continuum of global ethnic differences in this context.

A retrospective study of the incidence of diagnosed Type 1 diabetes among children and adolescents in a large health organization in Israel, 2000-2008

AIMS

To determine the incidence and examine temporal trends of Type 1 diabetes among children aged < 18 years, in a large Israeli health organization.

METHODS

All incident Type 1 diabetes cases diagnosed between 2000 and 2008 were ascertained from an automated diabetes registry based on members' electronic records and validated by comparison with the Israel Juvenile Diabetes Register.

RESULTS

During the study period, a total of 648 incident cases of Type 1 diabetes were identified. The average annual age-and-sex-standardized incidence was 11.09 per 100,000 person-years. There was an annual 5.82% (95% CI 1.80-9.98%) rise in incidence, with a greater relative increase in toddlers under 5 years of age. Incidence increased with age and demonstrated seasonal variation. Mean age at onset of diabetes significantly (P = 0.07) decreased from 10.21 years (SD = 4.48) in 2000-2002 to 9.25 years (SD = 4.54) in 2006-2008. Among very young patients (< 5 years), average blood glucose values at diagnosis dropped from 32.4 mmol/l (SD = 9.5) to 19.5 mmol/l (SD = 11.0) over the study period, with little change in average glucose for older children.

CONCLUSIONS

Incidence of diagnosed Type 1 diabetes continues to increase in Israel at a rate that is high compared with similar American and European populations. At the same time, the clinical presentation of children is changing.

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.

Joint genetic susceptibility to type 1 diabetes and autoimmune thyroiditis: from epidemiology to mechanisms

Type 1 diabetes (T1D) and autoimmune thyroid diseases (AITD) frequently occur together within families and in the same individual. The co-occurrence of T1D and AITD in the same patient is one of the variants of the autoimmune polyglandular syndrome type 3 [APS3 variant (APS3v)]. Epidemiological data point to a strong genetic influence on the shared susceptibility to T1D and AITD. Recently, significant progress has been made in our understanding of the genetic association between T1D and AITD. At least three genes have been confirmed as major joint susceptibility genes for T1D and AITD: human leukocyte antigen class II, cytotoxic T-lymphocyte antigen 4 (CTLA-4), and protein tyrosine phosphatase non-receptor type 22. Moreover, the first whole genome linkage study has been recently completed, and additional genes will soon be identified. Not unexpectedly, all the joint genes for T1D and AITD identified so far are involved in immune regulation, specifically in the presentation of antigenic peptides to T cells. One of the lessons learned from the analysis of the joint susceptibility genes for T1D and AITD is that subset analysis is a key to dissecting the etiology of complex diseases. One of the best demonstrations of the power of subset analysis is the CTLA-4 gene in T1D. Although CTLA-4 showed very weak association with T1D, when analyzed in the subset of patients with both T1D and AITD, the genetic effect of CTLA-4 was significantly stronger. Gene-gene and genetic-epigenetic interactions most likely play a role in the shared genetic susceptibility to T1D and AITD. Dissecting these mechanisms will lead to a better understanding of the etiology of T1D and AITD, as well as autoimmunity in general.

Type 1 diabetes in Jewish Ethiopian immigrants in Israel: HLA class II immunogenetics and contribution of new environment

The interrelationship between human leukocyte antigen immunogenetics and environmental factors and their contribution to the emergence of type 1 diabetes (T1D) were studied in Jewish immigrants from Ethiopia in Israel. This community displays high incidence of T1D, and is unique both by its ethnic segregation and its rapid exposure to a new environment after the immigration. The study population consisted of 152 Ethiopian Jews living in Israel, 33 with T1D and 119 unrelated controls. Human leukocyte antigen class II susceptible and protective alleles in the Jewish Ethiopian patients were similar to those in patients of other ethnic groups in Israel and in non-Jewish Ethiopian patients, with a few exceptions. Three haplotypes were markedly associated with diabetes in Jewish Ethiopian patients: DRB1*0301 DQA1*05 DQB1*02 (OR 4.4, p < 0.001); DRB1*0404 DQA1 03 DQB1*0302 (OR 19.2, p = 0.006), and DRB1*0405 DQA1*03 DQB1*0302 (OR 87.8, p < 0.001). The highly susceptible allele DRB1*0301 was more common in the general Ethiopian population (25.2%) than in all other ethnic groups in Israel, which may render this community prone to the disease. The age at onset of disease in patients with two susceptible haplotypes was negatively correlated with the duration of living in Israel (r = -0.621, p = 0.04). We concluded that ongoing exposure of genetically predisposed immigrants from Ethiopia to diabetogenic environmental factors eventually leads to a high incidence of overt diabetes in this ethnic group.

Younger age at diagnosis of type 1 diabetes mellitus in children of immigrated families born in Italy

The aim of this study was to evaluate the age of immigrants' children at diagnosis of Type 1 diabetes (T1DM) according to their country of birth. Immigration from developing countries to a westernised area causes rapid changes in the environmental conditions, and we investigated whether the location of birth, either inside or outside Italy, is associated with age at diagnosis of diabetes. Out of a prevalent hospital-based cohort of 5718 T1DM children cared for in 2002 in 47 Italian Pediatric Diabetes Units, we recruited 195 children (M: 97) of immigrants from developing countries--119 were born in Italy and 76 outside the European Union. Children with only one immigrant parent (no. 42) were also included. Age at diagnosis of T1DM, and other variables were compared with those of Italian children. Children of immigrated families born in Italy developed T1DM at a median age of 4.0 yr (IQR 2.2-6.9), whereas those born in developing countries and that had immigrated to Italy after birth developed T1DM at a median age of 7.9 yr (IQR 5.1-10.7, p < 0.001). Among the children born in Italy, 77 had parents who were both immigrants and the children's median age at diagnosis was 3.8 yr (IQR 2.1-6.3); 42 had only one immigrant parent and, when it was the father (no. = 23), median age was even younger (2.9 yr, IQR 2.0-8.2). Ten children had immigrated in their first yr of life and their median age was 9.1 yr (IQR 5.0-10.6). The median age of the Italian children was 6.6 yr (IQR 3.6-9.5). Results show that the outbreak of T1DM is earlier in immigrants' children born in Italy than in original countries.

An increasing trend in the incidence of type 1 diabetes mellitus in children aged 0-14 years in Romania--ten years (1988-1997) EURODIAB study experience

AIM

To assess the incidence of type 1 diabetes mellitus (DM1) in Romanian children aged 0-14 years using EURODIAB Study methodology.

METHODS

Data were collected for a 10-year interval (1988-1997) for the whole country, using the capture-recapture method.

RESULTS

We registered 1,418 newly diagnosed patients. The mean total incidence rate was 3.051/100,000/year. There was a wide geographic variation (6.71-fold) between the highest and the lowest incidence rates in different districts. We noticed a progressive increase of age-specific incidence rates from 1.43/100,000/year for the 0-4 year age subgroup to 4.37/100,000/year (10-14 years). The annual mean incidence rate rose from 1.91/100,000/year (1988) to 3.94/100,000/year (1996).

CONCLUSIONS

Romania is one of the European countries with the lowest incidence rates (3.051/100,000/year) for DM1 in children. There was an evident increasing trend of DM1 incidence in children between 1988 and 1997, with an annual increase of 7.57%.

Increasing incidence of Type 1 diabetes--role for genes?

BACKGROUND

The incidence of Type 1 diabetes (T1DM) is increasing fast in many populations. The reasons for this are not known, although an increase in the penetrance of the diabetes-associated alleles, through changes in the environment, might be the most plausible mechanism. After the introduction of insulin treatment in 1930s, an increase in the pool of genetically susceptible individuals has been suggested to contribute to the increase in the incidence of Type 1 diabetes.

RESULTS

To explore this hypothesis, the authors formulate a simple population genetic model for the incidence change driven by non-Mendelian transmission of a single susceptibility factor, either allele(s) or haplotype(s). A Poisson mixture model is used to model the observed number of cases. Model parameters were estimated by maximizing the log-likelihood function. Based on the Finnish incidence data 1965-1996 the point estimate of the transmission probability was 0.998. Given our current knowledge of the penetrance of the most diabetic gene variants in the HLA region and their transmission probabilities, this value is exceedingly unrealistic.

CONCLUSIONS

As a consequence, non-Mendelian transmission of diabetic allele(s)/haplotype(s) if present, could explain only a small part of the increase in incidence in Finland. Hence, the importance of other, probably environmental factors modifying the disease incidence is emphasized.

Interplay between heredity and environment in the recent explosion of type 1 childhood diabetes mellitus

The fast increase in the incidence of childhood type 1 diabetes mellitus (T1DM) that cannot be explained by changes in the genetic susceptibility, led us to look for environmental causes. To test the hypothesis that the initiation of the autoimmune process of childhood T1DM in genetically susceptible subjects begins in the perinatal period by a viral infection, we studied the seasonal variations in the month of birth of several cohorts of patients compared to the general population. Population groups with high or low T1DM incidence were analyzed separately by t-test and the Cosinor methods. In areas with populations with a high incidence (Israeli Jews, Sicily, Sardinia, Slovenia, Germany) we found that the children (in Sicily also young adults) who subsequently developed T1DM, have a higher incidence of births in the summer months than in other seasons of the year, a mirror image of the seasonality of the clinical onset of disease. This pattern differed significantly from the seasonality of the total live births in the same populations. In populations with a low T1DM incidence, (China, Japan and Cuba) no seasonality of month of birth was found. Similar findings have been reported, from five counties in the U.K. and the Netherlands. It is hypothesized that mothers who become pregnant during the period of yearly viral epidemics transmit to the fetus, either a virus or antiviral antibodies, which determine whether an autoimmune process against the pancreatic beta is initiated or whether the fetus is protected against that process.

Trends in the incidence of childhood diabetes in south Asians and other children in Bradford, UK

AIMS

To investigate incidence rates and time trends, over 21 years, of Type 1 diabetes in a migrant population of south Asian children in Bradford, UK.

METHODS

Children (0-14 years) living in the city of Bradford and diagnosed with Type 1 diabetes were selected from a population-based region-wide register. Between 1978 and 1998, 289 new-onset cases were registered and classified as south Asian (Indian, Pakistani, Bangladeshi) or not, based on their full name using two different computer algorithms and visual inspection.

RESULTS

Sixty-six children (22.8%) were designated as south Asian with 223 (77.2%) remaining. The overall age-sex standardized incidence for south Asian and non-south Asian children was 13.0 per 100,000 person years (95% confidence interval 9.9-16.2) and 12.9 (11.2-14.6), respectively. Rates were similar for south Asians at all ages, whereas for the mainly Caucasian children incidence differed significantly by age group (P < 0.001). An average annual increase in incidence of 4.3% (P = 0.001) was seen for all children compared with 6.5% in south Asians (P = 0.002) and 2.4% (P = 0.128) in non-south Asians.

CONCLUSIONS

Children in south Asia have a low incidence of Type 1 diabetes but migrants to the UK have similar overall rates to the indigenous population. However, a more steeply rising incidence is seen in the south Asian population, and our data suggest that incidence in this group may eventually outstrip that of the non-south Asians. Genetic factors are unlikely to explain such a rapid change, implying an influence of environmental factors in disease aetiology. The similarity in rates by age group in the south Asian population is notable.

Childhood and adolescent diabetes mellitus in Arabs residing in the United Arab Emirates

In 9 years (1990-1998), 40 Arab patients between the ages of 0 and 18 years had newly diagnosed diabetes mellitus (DM) at the Al-Ain hospital, United Arab Emirates (UAE). In this cohort, 35 patients had Type 1 DM while the remaining five patients had features of early onset Type 2 DM. For Type 1 DM patients, the mean age at diagnosis of was 9.2+/-4.1 years. At presentation, their mean plasma glucose was 27.6+/-11/mmol with 28 (80%) patients having diabetic ketoacidosis (DKA), both being much higher than generally reported in the West. The mean insulin requirement increased from 0.84+/-0.27 U/kg per 24 h (0-9-year group) to 1.02+/-0.33 U/kg per 24 h (10-18-year group), P=0.055. The home glucose monitoring and the glycaemic control of these Type 1 DM patients were sub-optimal with 28% of patients having recurrence of DKA. Among the Type 2 DM patients, four (80%) were obese with a positive family history of Type 2 DM. All of them initially responded to diet and oral hypoglycaemic drugs. Public education about DM in childhood and prevention of adolescent obesity remain major public health challenges in the UAE.

Type 1 diabetes environmental factors and correspondence analysis of HLA class II genes in the Yemenite Jewish community in Israel

OBJECTIVE

The Israeli Yemenite Jewish community has displayed an exceptionally rapid increase in the frequency of type 1 diabetes, having the highest rate of all Israeli ethnic groups. We studied the role of the environment, in relation to the nature and frequency of HLA class II genes, to evaluate its possible involvement in the development of diabetes.

RESEARCH DESIGN AND METHODS

We interviewed 196 elderly Yemenite women, who had immigrated to Israel as adults, in programmed encounters about signs and symptoms of type 1 diabetes, infant feeding customs, and infectious diseases in Yemen. We also performed HLA oligotyping of DRB1, DQA1, and DQB1 genes in 120 unrelated Yemenite Jews, including 44 type 1 diabetic patients and 76 healthy control subjects, and used these data in correspondence analysis comparing Yemenites with different Israeli ethnic groups.

RESULTS

Interviews indicated that early exposure to cow's milk was very common in Yemen. However, none of the women could recall classical presentations of diabetes. HLA oligotyping showed that gene frequencies of non-Asp-57 (of the HLA-DQB chain) in the patients (0.94) and control subjects (0.6) were similar to those of other populations with a known high incidence of type 1 diabetes. Correspondence analysis revealed that Yemenite Jews are genetically distinct from other ethnic groups in Israel.

CONCLUSIONS

The genetic distinctiveness of Yemenite Jews may explain their unusually high incidence of type 1 diabetes in Israel. Despite the presence of highly susceptible diabetogenic HL4 class II genes in this community, early exposure to cow's milk did not cause phenotypic expression of diabetes in Yemen. This finding suggests that in this population, either cow's milk does not play a crucial role in triggering diabetes, or environmentally conferred protection, such as frequent infectious disease in Yemen, was dominant.

Seasonality of birth in children (0-14 years) with type 1 diabetes mellitus in Slovenia

The aim of this study was to find out whether there is seasonality of month of birth of children with diabetes in Slovenia and if so whether it differs from that of the general population. A cohort of 849 children and adolescents (0-14 years) with type 1 diabetes mellitus born between 1956 and 1998 were included in the study. Monthly and seasonal patterns of birth of the patients with diabetes were compared with the pattern of normal live births (n = 1,345,921) and the pattern of disease onset. Statistical analysis was made using Student's t-test to compare the means between the four seasons of the year, and single cosinor analysis for a period of 12 months. The children and adolescents with diabetes had a statistically significant different seasonality of month of birth compared to that of the general population, and an opposite pattern from the seasonality of month of onset of disease. The observations made are in accordance with observations made recently in other countries and support the hypothesis that a virus infection transmitted by the mother to the fetus during the annual viral epidemic induces the autoimmune process in the pancreatic beta-cells in genetically susceptible individuals who will subsequently develop clinical diabetes during childhood.

Immunogenetics of HLA class II in Israeli Ashkenazi Jewish, Israeli non-Ashkenazi Jewish, and in Israeli Arab IDDM patients

The distribution of HLA class II alleles and genotypes in IDDM patients was examined in the three main Israeli ethnic groups: Ashkenazi Jews, non-Ashkenazi Jews, and Arabs. Molecular sequence specific oligonucleotide probe analysis was performed for DRB1, DQA1, and DQB1 genes. The DRB1*03011, DQA1*05 DQB1*02/DRB1*0402, DQA1*03, DQB1*0302 genotype was found to be the main susceptibility genotype in all three groups, with differences in the degree of association. In addition to DRB1*0402 (more frequent among Ashkenazi Jews), DRB1*0405, another subtype of DRB1*04, was found to be more prevalent among non-Ashkenazi Jews and Arabs. Many alleles were found to be negatively associated with insulin dependent diabetes mellitus (IDDM). This could be a result of the high frequency of susceptible alleles, or of linkage disequilibrium to a primary negatively associated allele. The strongest negative association was observed for DQB1*0301 in all three ethnic groups. The alleles DRB1*1401, DRB1*1501, DQB1*05031, DQB1*0602, and DQB1*0609 were not detected in any of the 202 IDDM patients, and are probably either strongly protective or in linkage with such alleles. Despite the differences found between the three ethnic groups, an overall analysis shows that the DRB1*04 alleles that account for susceptibility to IDDM in the Israeli population (DRB1*0402 and *0405) are the same as those responsible for susceptibility to IDDM in a number of other Mediterranean populations. In contrast, the susceptible allele in most Caucasian populations is DRB1*0401. It is noteworthy that the susceptible alleles DRB1*0402/05 for Mediterranean and DRB1*0401 for Caucasian populations are also frequent in the respective healthy populations. These findings support the results obtained in other studies, which point to a genetic relationship between the Israeli and Mediterranean populations.

Familial predisposition of type 1 diabetes mellitus in Japan, a country with low incidence. Japan Diabetes Society Data Committee for Childhood Diabetes

The study group of the Japan Diabetes Society (JDS) carried out nationwide hospital-based and population-based surveys of childhood type 1 diabetes mellitus (DM) in Japan. According to the nationwide population-based survey, the incidence of childhood type 1 DM in Japan was 1.5 (1.4-1.6)/10(5), which did not differ for the 5 years from 1986-1990. Predisposition for DM and autoimmunity were studied in the first-degree relatives of the patients, including older and later cohorts. The prevalence of type 1 DM was 3.3% (12/369) among siblings and 2.2% (8/369) among parents, while the prevalence of type 2 DM was 0% among siblings and 4.3% (16/369) among parents. The risk of type 1 DM among siblings of the patients was 330 times higher than that among the general population in the Japanese population. The rate of positivity for autoantibodies, including ICA, IAA, GAD and IA-2, was 1.4-2.9% in parents (n=140) and 2.0-3.9% in siblings (n=203). The genetic susceptibility for type 1 DM is far lower in Japanese children than in Caucasian children, but predisposition to the disease and positive autoimmunity are almost the same in Japanese families of patients as in Caucasian families. The quality of life of Japanese parents of children with type 1 DM was less satisfactory that that of the Caucasian parents previously reported, which might be a result of the low incidence of type 1 DM in Japan.

Month of birth and subsequent development of type I diabetes (IDDM)

The aim of this study was to find out whether there is a seasonal pattern in the month of birth of children with IDDM in Israel and whether this pattern, if present, differs from that of total live births. One thousand and ninety-five out of 1,188 children and adolescents (0-17 years) who developed IDDM in Israel between 1980-1993 and whose month of birth was known were included in the study. Separate analysis was made for Jews (n = 987) who have a high incidence (10-18/105) and Arabs (n = 108) with a low incidence (2.9/105) of IDDM. The pattern of total live birth distribution in Israel over a 20-year period served as control. A significantly different seasonal pattern was found in the two IDDM populations. Whereas the Jews had the lowest number of births in winter (January-March) and the highest in spring (April-June), the Arabs presented an inverse pattern in the first months of the year. The distribution of births of the children who developed IDDM was different from that observed in total live births in the Jewish population. The findings in the Jewish population in Israel (a high incidence group) support the hypothesis that IDDM is triggered in some children by viral infections transmitted by the mother during pregnancy or in the early postnatal period. In the Arab population (a low incidence group) a protective (immune and/or genetic) mechanism may exist.

New insights into the epidemiology of type 1 diabetes in Mediterranean countries

In Mediterranean countries, the incidence (per 100,000 per year) of Type 1 diabetes in children aged under 15 years shows wide variation from country to country, ranging from 2.45 in Macedonia to 34.4 in Sardinia. By interacting with environmental factors such as diet, toxins or viral infections, the HLA plus non-HLA genes of susceptibility or resistance to Type 1 diabetes so far identified are the strongest determinants of the disease as far as incidence, age at onset and sex ratio are concerned. The distribution of these genes in the Mediterranean region is still not completely known. Sardinians are the most suitable population for studying such phenomena for three main reasons: their genetic features have been repeatedly analysed in depth; their incidence rate of Type 1 diabetes is by far the highest in the Mediterranean area; and considerable colonies of Sardinian emigrants settled in neighbouring low-incidence Italian regions. Studies on Spaniards and Jews have also contributed to a better understanding of the respective roles of genetic and environmental factors. From a body of research on the Mediterranean populations, it can be concluded that great genetic heterogeneity accounts for the wide variation in incidence of Type 1 diabetes, while rather ubiquitious environmental factors trigger the disease in genetically predisposed individuals.

Migrant populations and the incidence of type 1 diabetes mellitus: an overview of the literature with a focus on the Spanish-heritage countries in Latin America

Type 1 diabetes mellitus (DM) is a 'chronic' autoimmune disorder leading to the destruction of the pancreatic beta cell. The natural history of diabetes includes a long subclinical (prediabetes) period. The pathogenesis is multifactorial and characterized by the interaction of environmental factors, with predisposing genes, most of which are associated with the HLA DR DQ loci. The relatively recent development of worldwide incidence registries for Type 1 DM has allowed us to compare the epidemiological results obtained in most parts of the world. This approach is particularly valuable in analysing the effects of migration of populations from one area of the world where the incidence of Type 1 DM is different (usually lower) to a new geographic setting. Properly designed migrant studies may be valuable in uncovering whether the genetic background remains more important than the new 'exposure' as illustrated by the Sardinian migration to Lazio and Lombardy. The presence of some putative 'protective' environmental exposures or the absence of those prevalent in the country of origin may explain the usually lower Type 1 DM incidence observed in most countries (Chile, Peru, Mexico) sharing a 'Spanish caucasoid genetic pool', and even in relatively genetically homogeneous groups such as Japanese populations migrating to Hawaii. In fact, the disease is caused by both genetic and environmental factors and to convince the scientific community of this fact is a primary responsibility for epidemiologists.

Incidence of insulin-dependent diabetes mellitus in Jordanian children aged 0-14 y during 1992-1996

An attempt was made by the Jordanian National Center for Diabetes, Endocrine and Genetic Diseases (NCDEGD) to identify all cases of type 1 diabetes among Jordanian children aged 0-14 y. Data were obtained retrospectively for the years 1992-1994 and prospectively for the years 1995 and 1996, including full name, national identifying number, date of birth, date of diagnosis and family history. The incidence was calculated as the number of cases per 100,000 population, according to the national census of 1994. The incidence rate for these years (1992 through 1996) was 2.8, 2.9, 3.2, 3.6 and 3.6 per 100,000 population, respectively. The male:female ratio was (1:1.03). Seasonal variation at clinical onset was noticed, with maximum incidence in the winter months and minimum incidence in the summer months. In conclusion, the incidence of type 1 diabetes mellitus in Jordanian children aged 0-14 y is among the lowest in the region, but is rising.

HLA class II immunogenetics of IDDM in Yemenite Jews

The association between HLA-DR and DQ and insulin dependent diabetes mellitus (IDDM) was analyzed in 47 patients and 76 controls of Yemenite Jewish origin. The IDDM susceptibility alleles DRB1*03011, DQA1*0501, DQB1*02 and DRB1*0402, DQA1*0301, DQB1*0302 found in Caucasians had a very strong predisposing effect also in the Yemenite IDDM group. The DRB1*07, DQA1*0201 and DQB1*02 alleles were found to have a strong negative association with IDDM. None of the patients carried DRB1*07 and DQA1*0201 compared with healthy controls (43.7%). Our analysis revealed that the DRB1*03011 DQA1*0501 DQB1*02/DRB1*04 DQA1*03 DQB1*0302 heterozygous genotype confers the highest susceptibility (59.6% in patients vs. 0% in controls). The homozygous DRB1*03 and DRB1*04 genotypes were also found to be positively associated with the disease. 81% of the patients compared to 1.3% of controls carried the susceptibility alleles on both haplotypes. In conclusion, the development of IDDM in Yemenite Jews is strongly dependent on the presence of the susceptibility HLA alleles and on the absence of the DRB1*07 haplotype. The Yemenite Jewish group is uniquely homogenous with regard to genetic susceptibility factors involved in the process of IDDM, and may thus be an ideal model for further genetic studies.

Lack of seasonality in the month of onset of childhood IDDM (0.7-15 years) in Shanghai, China

A cohort of 136 children from Shanghai with insulin dependent diabetes mellitus (IDDM) (0.7-15 years) were analyzed for the month of onset of disease and month of birth. In contradistinction to populations with a medium or high incidence of IDDM, no seasonality was registered in the month of onset. On the other hand there was a significant (p < 0.026) seasonality in the month of birth (peak November to January), but which differed in pattern to that observed in populations with medium or high incidence. Our findings support the hypothesis that the initiation of IDDM is due to a viral infection and that one cause for the low incidence of childhood IDDM in certain populations is immunization against infectious pathogens in their early life.