H. J. Bodansky

Evidence for an environmental effect in the aetiology of insulin dependent diabetes in a transmigratory population.

OBJECTIVE--To examine whether children of families moving from an area of low incidence of childhood diabetes to one which is higher show a corresponding rise in disease incidence. DESIGN--Disease incidence study over 12 years. SETTING--Bradford District Metropolitan Council area. SUBJECTS--All subjects aged 0-16 years resident within the study area. MAIN OUTCOME MEASURES--The incidences of childhood diabetes in Asian and non-Asian families. RESULTS--The incidence of diabetes in Asian children increased from 3.1/100,000 per year in 1978-81 to 11.7/100,000 per year in 1988-90 (chi 2 for trend = 4.95, df = 1, p = 0.026) whereas that for other children remained constant at 10.5/100,000 per year. Over the entire study period rates were lower in Asian females (4.9/100,000 per year) than in Asian males (8.8/100,000 per year) whereas the reverse was true for other children (males 9.2/100,000 per year; females 12.0/100,000 per year) (test for common odds ratio: chi 2 = 3.81, df = 1, p = 0.052). CONCLUSIONS--Offspring of this transmigratory population had a rising incidence of childhood diabetes which was approaching that of the indigenous population. The data provide strong evidence for an environmental effect in the aetiology of insulin dependent diabetes.

Incidence of childhood diabetes mellitus in Yorkshire, northern England, is associated with nitrate in drinking water: an ecological analysis.

Summary The relationship between the incidence of childhood-onset insulin-dependent diabetes mellitus and levels of nitrate in drinking water in the former Yorkshire Regional Health Authority was investigated by means of an ecological analysis. A population-based register contributed 1797 0–16-year-olds diagnosed with diabetes between 1978 and 1994. Nitrate data were based on 9330 samples of drinking water tested between 1990 and 1995 in 148 water supply zones, for which 1991 census small area statistics were taken on population density, ethnicity and socio-economic status. Diabetes incidence was positively associated with raised mean nitrate levels with a standardised incidence ratio of 115 in zones with greater than 14.85 mg · l–1 (χ2 = 26.81, 1 df, p < 0.001). Significant negative trends were found between standardised incidence ratios and proportion of non-whites in the population (χ2 = 33.57, 1 df, p < 0.001), childhood population density (χ2 = 30.81, 1 df, p < 0.001) and the Townsend deprivation score (χ2 = 33.89, 1 df, p < 0.001). Poisson regression modelling, adjusting for the other factors, showed a significant increase in relative incidence rate ratio from a baseline of 1 at nitrate levels below 3.22 mg · l–1 to 1.27 (95 % confidence interval 1.09,1.48) for mean nitrate levels above 14.85 mg · l–1. An association between higher nitrate levels in domestic drinking water and incidence of childhood diabetes has been demonstrated. This was not explained by the ethnic composition of the population, population density or socioeconomic status. Nitrate in drinking water may be a precursor of chemicals which are toxic to the pancreas. [Diabetologia (1997) 40: 550–556]

Early social mixing and childhood Type 1 diabetes mellitus: a case–control study in Yorkshire, UK

Aimsu2003Evidence from animal models shows an increased risk of Type 1 diabetes mellitus associated with the absence of early life exposure to pathogens. To test this ‘hygiene hypothesis’, patterns of social mixing and infections in the first year of life and the risk of developing autoimmune diabetes in childhood were examined.

Type 1 diabetes in Yorkshire, UK: time trends in 0–14 and 15–29-year-olds, age at onset and age-period-cohort modelling

Aims To investigate whether the rising incidence of Type 1 diabetes in children is evident in young adults and determine whether age at onset has decreased over time.

Type 2 and other forms of diabetes in 0–30 year olds: a hospital based study in Leeds, UK

Background and Aims: Following recent reports of increased numbers of adolescents being diagnosed with the adult or type 2 form of diabetes we aimed to describe the prevalence of both type 2 and other forms of diabetes in an urban population of children and young people in northern England. Methods: A hospital based cross sectional study was performed in patients aged ≤30 years attending diabetic clinics in Leeds during the year 2000. Results: A total of 677 subjects were identified, of whom 621 (92%) and 37 (5%) had type 1 and type 2 diabetes respectively. Four patients had confirmed maturity onset diabetes of the young, while the cause was uncertain for four. Median age of all patients was 22 years, with 396 (58%) aged 20–30; 32/37 patients with type 2 diabetes were aged 20–30. The prevalence of type 2 diabetes was 0.13 per 1000 overall, compared to 2.2 per 1000 for patients with type 1 diabetes. Of all type 2 diabetes patients, 24% were south Asian compared to 5% of the background population; 87% were categorised into the two least affluent tertiles of the Townsend score. This link with deprivation was not explained by the proportion of Asian patients across tertiles (approximately 25%). Conclusions: This study shows extremely low prevalence of type 2 diabetes in 10–19 year olds, but will provide a baseline for future comparisons. Overall, type 2 diabetes is seen more commonly in south Asians, and an association with deprivation is suggested.

Antenatal risk factors for childhood diabetes mellitus; a case-control study of medical record data in Yorkshire, UK

Summary Environmental risk factors for childhood insulin-dependent diabetes mellitus (IDDM) have been investigated using data abstracted from the obstetric records of mothers participating in a population-based case-control study of children (0–15 years) diagnosed with IDDM during 1993–1994. A univariate analysis of 196 age and sex matched sets (129 triplets, 67 pairs) gave significantly raised odds ratios (OR) for mothers over 35 years (OR 2.13, 95 %CI 1.04–4.36) and the following exposures in pregnancy: amniocentesis (3.85, 1.34–11.04), oedema, proteinuria and/or hypertensive disorders (1.62, 1.03–2.54), excessive weight gain (7.12, 1.50–33.79) and complications in labour (1.49, 1.00–2.21). The risk previously associated with caesarean deliveries was confirmed and the trend of increasing risk with age was significant. Adjusting separately for mothers with IDDM (4 cases, 0 control subjects), parity and small for gestational age failed to have any influence on the pregnancy risk factors or caesarean delivery. Case mothers undergoing amniocentesis were significantly younger compared to their control counterparts (p = 0.02) and the majority were given the test to determine fetal maturity, late in pregnancy, rather than to identify chromosomal abnormalities. Oedema, proteinuria and/or hypertension conferred an increased risk throughout pregnancy, particularly in the first two trimesters. No specific pattern of risk was present for any age group. Multivariate modelling of the significant OR, using conditional logistic regression, retained excessive weight gain as significant. The overall results present a risk profile of older mothers whose babies may be exposed to adverse intrauterine conditions and delivery by caesarean section. [Diabetologia (1997) 40: 933–939]

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.

The epidemiology of diabetes mellitus in the United Kingdom: The Yorkshire regional childhood diabetes register

SummaryA 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%).

Mortality and diabetes from a population based register in Yorkshire 1978-93

OBJECTIVE To investigate mortality of children diagnosed with insulin dependent diabetes mellitus (IDDM) and to identify common factors before death. DESIGN Follow up of a population based cohort of children diagnosed with IDDM to ascertain deaths. SETTING Children were diagnosed in Yorkshire but followed up throughout the United Kingdom. SUBJECTS From the Yorkshire Children’s Diabetes Register details of 1854 children aged 0–16 years (1978–93) were submitted to the NHS Central Register. MAIN OUTCOME MEASURE Notification and causes of death. RESULTS 98.3% of cases were traced and 26 deaths identified. Follow up ranged from 1–18 years (median 9.3 years), providing 17u2009350 person-years of IDDM. Fifteen deaths (58%) were attributed to diabetes or its complications; 11 (42%) were unrelated and included one suicide. For mortality from all causes, the standardised mortality ratio (SMR) of 247 (95% confidence interval (CI) 163 to 362) was significantly increased for those under 34 years. The largest number of deaths (nu2009=u200910) occurred in the 15–19 year age range, with an SMR of 442 (95% CI 209 to 802). Case note examination showed a clear tendency towards poor diabetic control, and worries over control were expressed before death by health care professionals. CONCLUSIONS Despite advances in treatment, IDDM still carries an increased mortality for young people, particularly in the “transition” age range.

Geographical mapping of childhood diabetes in the northern English county of Yorkshire.

This study aimed to highlight geographical differences in childhood Type 1 (insulin dependent) diabetes mellitus (IDDM) by mapping incidence at 3 different geographical scales, within the northern English county of Yorkshire. Mapping techniques are applied to incident cases from a population‐based regional register of childhood IDDM. The Yorkshire Childrens Diabetes Register (YCDR) comprises 1310 children (0–14 years) diagnosed with IDDM from 1978–1990. Age standardized incidence rates (cases/100 000/year) are given for administrative county, standardized incidence ratios (SIRs) are mapped by local government district and electoral ward. Heterogeneity between areas was assessed by a χ2 test. At county level, incidence is 25u2009% higher in Humberside (16.82 per 100000 per year) compared to West Yorkshire (12.21 per 100000 per year) (p<u20090.001). SIRs for the 22 districts display significant heterogeneity (p<u20090.001) with deficits in the urban areas of Kirklees (70 95% CI 57–85) and Bradford (81 95% CI 68–95) and significant excesses in the rural districts of Ryedale (147 95% CI 106–198), Beverley (149 95% CI 113–193), Holderness (166 95% CI 112–237) and Boothferry (186 95% CI 134–250). At the smallest scale, variation between wards is significant (pu2009<u20090.001) and low incidence in urban areas is notable. Geographical variation in the incidence of childhood IDDM may provide strong clues to its aetiology. Within Yorkshire, geographical distribution shows significant heterogeneity at three different scales. The magnitude of the variation is not explained by ethnic or genetic differences in the population and underlines the important influence of environmental factors in disease aetiology.