The incidence of childhood diabetes in certain parts of Scotland

Enteroviruses, type 1 diabetes and hygiene: a complex relationship

Type 1 diabetes (T1D) is an autoimmune disease in which the immune system mounts an attack on the host's insulin‐producing β cells. Because most cases of T1D cannot be attributed only to individual genetics, it is strongly inferred that there is a significant environmental contribution, such as infection, impacting disease development. The human enteroviruses (HEV) are common picornaviruses often implicated as triggers of human T1D, although precisely which of the numerous HEV may be involved in human T1D development is unknown. Experiments using non‐obese diabetic (NOD) mice, commonly used to model T1D, show that induction of T1D by HEV infection in NOD mice is a multifactorial process involving both the virus and the host. Interestingly, results demonstrate that HEV infection of NOD mice can also induce long‐term protection from T1D under certain conditions, suggesting that a similar mechanism may occur in humans. Based upon both experimental animal and observational human studies, we postulate that HEV have a dual role in T1D development and can either cause or prevent autoimmune disease. Whichever outcome occurs depends upon multiple variables in the host‐virus equation, many of which can be deduced from results obtained from NOD mouse studies. We propose that the background to the sharply rising T1D incidences observed in the 20th century correlates with increased levels of hygiene in human societies. Viewing T1D in this perspective suggests that potential preventative options could be developed. Copyright © 2009 John Wiley & Sons, Ltd.

Exposure to farming environments in early life and type 1 diabetes: a case-control study

It has been hypothesized that a stimulation of regulatory cytokines by microbial compounds reduces autoimmune as well as atopic diseases. Farm-related contact to microbial compounds protects from allergies, but no data on the association between farm contact and type 1 diabetes is available. The aim of this study was to test this association. A case-control study was conducted in five children's hospitals. Regular contact to farm animals and potential confounders were assessed using a postal questionnaire. Eligible subjects were all prevalent cases with type 1 diabetes registered in the hospitals and hospital-based control subjects (response rate 91%). Included were children aged 6-16 years living in rural areas with German nationality (242 case and 224 control subjects). Regular contact to stables (adjusted odds ratio 1.2 [95% CI 0.5-2.7]) was not associated with type 1 diabetes. In addition, regular contact to specific farm animals was not associated with case status. There was a tendency for an inverse relationship between allergic rhinitis and type 1 diabetes (0.6 [0.3-1.1]; P = 0.11). There was no evidence that early exposure to farm animals largely decreases the risk in children for developing type 1 diabetes.

Drinking water composition and childhood-onset Type 1 diabetes mellitus in Devon and Cornwall, England

AIMS

Previous studies have reported inconsistent results on the association between some compositions (e.g. nitrate) in domestic water and the risk of childhood-onset Type 1 diabetes mellitus. This study aimed to examine the relationship between nitrate, zinc and magnesium in drinking water and the risk of childhood-onset Type 1 diabetes mellitus.

METHODS

The study covers the Cornwall and the former Plymouth Health Authority Regions in the far south-west of England. Five hundred and seventeen children, aged 0-15 years, diagnosed with Type 1 diabetes mellitus between 1975 and 1996, were identified for inclusion in the study. Domestic water data (nitrate, Zn, Mg, Cu, Al, Ca, Fe and Mn) between 1993 and 1997 were provided by South-west Water Plc, UK, for each of the 40 Water Supply Zones in which the subjects had been resident at the time of diagnosis. The standardized incidence ratio (SIR) of the disease was calculated for each Water Supply Zone using the UK 1991 census population data. The relationship between the SIR of the disease and the water quality indicators in thirds (three strata of low, medium and high concentrations) was examined by chi2 test for trend and Poisson regression analysis.

RESULTS

The initial analyses by chi2 test for trend on the relation of SIRs and drinking water compositions suggested that copper, magnesium and nitrate might have some protective effects, but Poisson regression analyses showed that only zinc and magnesium were significant factors. The data suggest that the incidence rate of childhood diabetes is significantly lower when the concentrations of zinc and magnesium in the domestic drinking water are in the range 22.27-27.00 microg/l (incidence rate ratio (IRR), 0.76; 95% CI, 0.59-0.97) and greater than 2.61 mg/l (IRR, 0.72; 95% CI, 0.58-0.91), respectively.

CONCLUSIONS

Our findings suggest evidence of a possible association between zinc and magnesium in the domestic drinking water and childhood diabetes in the far south-west of England. However, these possible protective effects of zinc and magnesium in domestic drinking water warrant further confirmation.

Incidence of childhood-onset Type 1 diabetes mellitus in Devon and Cornwall, England, 1975-1996

AIMS

To determine the incidence of Type 1 diabetes mellitus (DM) in children aged 0-15 years in the far south-west of England between 1975 and 1996.

METHODS

Patient information was collected to set up the Cornwall and Plymouth Children's Diabetes Register (CPCDR) through two main data sources; hospitals and the general practitioners in all surgeries in the study region. All children under 16 years living within Cornwall and the Isles of Scilly, and the former Plymouth Health Authorities and diagnosed as having Type 1 DM during the study period were included. The case ascertainment was estimated by a capture-recapture method. Trends and differences in incidence of sex, age, time period and district of diagnosis were analysed by Poisson regression analysis. Roger's method was used to estimate the seasonal variations.

RESULTS

A total of 522 subjects aged between 0 and 15 years were identified from 01/01/1975 to 31/12/1996, giving an overall crude incidence of 14.9/ 100 000 population/year. The case ascertainment was 94.4% (95% confidence interval (CI) 91.4- 97.6%) for the whole register. Poisson regression analysis showed that a significant increase of incidence (2.49% per year) was observed throughout the 22-year study period, which was mainly a result of the significant increase in the 0-4 year age-group (6.29% per year). The incidence significantly differed among the 22-years (P = 0.007), the three age groups (0-4, 5-9 and 10-14 years, P<0.001) and different sexes (P=0.049). The significant seasonal variations were detected with peak incidence appearing in autumn and winter.

CONCLUSIONS

The first validated childhood-onset diabetes register has been set up in the far south-west of England. The incidence of childhood Type 1 DM in this region has increased significantly over the past two decades, especially in children under 5 years.

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)

Epidemiology of childhood IDDM in Northern Ireland 1989-1994: low incidence in areas with highest population density and most household crowding. Northern Ireland Diabetes Study Group

During the period 1989-1994, 462 cases of insulin-dependent diabetes mellitus were registered among children from Northern Ireland aged under 15 years. The estimated completeness of the register was 98.8% (95% confidence interval (CI) 97.7%, 99.9%). A standardised rate of 19.6 (95% CI 17.8, 21.4) per 100 000 person years was obtained, placing Northern Ireland near the top of the range of published incidence in the United Kingdom, with a rate close to that reported for Scotland. In an analysis based on 217 postcode sectors, areas with a high population density and the most material deprivation were observed to have the lowest incidence rates. After inclusion of population density in a Poisson regression analysis, the component of deprivation which was found to be most significant was household crowding. Relative to children living in areas of low population density, there was a reduced risk for children in medium (relative incidence 0.85 (95% confidence limits CI 0.67, 1.09)) and high (0.62 (95% CI 0.48,0.80)) population density areas. Similarly, relative to children living in areas with low levels of household crowding, there was a reduced risk for children in medium (relative incidence 0.73 (95% CI 0.58,0.93)) and high (0.67 (95% CI 0.53, 0.83)) levels of household crowding. Tests for space-time clustering at diagnosis and at birth were negative. A possible explanation for the differences in incidence rate observed in this study is that exposure to infections very early in childhood is a protective factor. Later infections may act as either initiators or promoters of diabetes, but the absence of space-time clustering suggests that no single specific infectious agent is responsible.

The epidemiology of diabetes mellitus in the United Kingdom: the Yorkshire Regional Childhood Diabetes Register

A register of the incidence of Type 1 (insulin-dependent) diabetes mellitus in the Yorkshire region of the United Kingdom has been completed. A total of 1,490 subjects aged between 0 and 16 years were identified from 1978 to 1990, giving an incidence of 13.7 per 100,000 (ages 0-14) or 13.6 per 100,000 (ages 0-16), comparable to other recent studies in the United Kingdom. An age-period-cohort analysis shows evidence for a modest drift effect of 1.75% per year (95% confidence interval 0.28 to 3.25%). There is a marked epidemic pattern with peaks at 4-year intervals. The age-incidence curve is similar to that reported elsewhere, having peaks in early childhood and puberty. Girls have an earlier pubertal peak than boys. There is substantial seasonal variation in incidence confined to those over 5 years of age. Ascertainment is believed to be very complete, and is estimated to be 97.6% (95% confidence interval 97.2% to 98.1%).

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.

Incidence of insulin dependent diabetes in children aged under 15 years in the British Isles during 1988

OBJECTIVE

To ascertain the annual incidence rate of insulin dependent diabetes diagnosed in children under the age of 15 years in the British Isles during 1988, and to compare the results with an earlier study carried out in 1973-4.

DESIGN

Active monthly reporting of cases by consultant paediatricians, with additional input from diabetologists and all specialist diabetes nurses and health visitors.

SETTING

British Isles (England, Wales, Scotland, Northern Ireland, Republic of Ireland) with a total population at risk of 11,819,000 children.

PATIENTS

All children diagnosed under the age of 15 years with primary insulin dependent diabetes from 1 January to 31 December 1988 and resident in the British Isles at diagnosis.

MAIN OUTCOME MEASURES

National incidence rate of insulin dependent diabetes; differences in incidence rates between regions and between three age groups: 4 and under, 5-9, and 10-14 year olds.

RESULTS

1600 children (837 boys and 763 girls) had a confirmed diagnosis of insulin dependent diabetes, giving a national incidence rate of 13.5/100,000/year (95% confidence interval 12.9 to 14.2/100,000/year). This was considerably higher than the incidence rate of 7.7/100,000/year in children under the age of 16 years reported in the British Diabetic Association's study of 1973-4. The age-sex adjusted rates varied between regions, ranging from 6.8/100,000/year (Republic of Ireland) to 19.8/100,000/year (Scotland). There were considerable differences in the numbers of cases diagnosed each month, with the 10-14 year age group showing the most seasonal variation. A quarter of the children (404/1600) were under 5 years old. Case ascertainment was estimated as 90%.

CONCLUSIONS

Insulin dependent diabetes in the British Isles does not seem to occur uniformly over time or geographical area. Even allowing for differences in ascertainment between the 1973-4 and 1988 studies, there seems to have been an increase in the incidence rate of insulin dependent diabetes in children under the age of 15 years during the 15 year time period. If diabetes is becoming more common in this age group, possibly by developing earlier in susceptible children, this would be a matter of considerable public health concern.