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

Population-Based Screening for Coeliac Disease in Lithuanian Children from 2009 to 2014

Background and Objectives. Coeliac disease is an autoimmune disorder provoked by a dietary group of proteins called gluten in genetically predisposed individuals. Over the past several decades, the prevalence of coeliac disease has been steadily growing and it is now recognized to be occurring worldwide. The prevalence varies greatly between ethnic, racial groups and regionally. Such variability makes local epidemiological studies important for spreading awareness and setting a threshold for suspicion of coeliac disease. We explored the potential application of a quick point-of-care test for the purpose of detecting a presence of IgA class TG2 antibodies for coeliac disease and screening in a Lithuanian pediatric population. Previously, there were no data regarding coeliac disease prevalence in Lithuania. Materials and Methods. Overall, we included 1458 children 11-13 years of age from several Lithuanian schools selected randomly in this study. Utilizing one point-of-care test using a single blood sample taken from a fingertip, we identified the existence of IgA class TG2 antibodies. Only children whose parents gave consent were enrolled in the study. Those with positive IgA class TG2-ab were directed to a tertiary hospital for additional clinical assessment and confirmation of suspected coeliac disease. Results. A total of two (0.14%) of the 1458 enrolled children were detected with the presence of TG2 antibodies and the coeliac disease diagnosis was further confirmed with histological examination of duodenal biopsy samples. Additionally, we checked that patients had not previously reported any clinical symptoms and signs that could suggest coeliac disease or any other disease of the gastrointestinal tract. Conclusions. The detected prevalence of coeliac disease in the Lithuanian pediatric population is 1:729. The rapid finger prick test for the presence of IgA class TG2 antibodies is a reasonable and accurate method to screen for celiac disease in children.

The impact of race and socioeconomic factors on paediatric diabetes

There are over 29,000 children and young people (CYP) with Type 1 diabetes mellitus (T1DM) in England and Wales and another 726 with Type 2 diabetes mellitus (T2DM). There is little effect of deprivation on the prevalence of T1DM whereas the association of deprivation on the percentage of CYP with T2DM is striking with 45% of cases drawn from the most deprived backgrounds. A number that has not changed over the last 4 years. Data from the UK and USA as well as other countries demonstrate the impact of deprivation on outcomes in diabetes mellitus with clear effects on measures of long-term control and complications. In the UK black CYP had higher glycosylated haemoglobin (HbA1c) values compared to other groups. Within the black group, CYP from a Caribbean background had a higher mean HbA1c (77.0 mmol/mol (9.2%)) than those from Africa (70.4 mmol/mol (8.6%)). Treatment regimen (multiple daily injections or insulin pump therapy) explained the largest proportion of the variability in HbA1c followed by deprivation. Those in the least deprived areas had an average HbA1c 5.88 mmol/mol (0.5%) lower than those living in the most deprived areas. The picture is complex as UK data also show that deprivation and ethnicity is associated with less use of technology that is likely to improve diabetes control. Increased usage of pump therapy and continuous glucose monitoring was associated with a younger age of patient (less than 10 years of age), living in the least deprived areas and white ethnicity. This gap between pump usage amongst CYP with T1DM living in the most and least deprived areas has widened with time. In 2014/15 the gap was 7.9% and by 2018/19 had increased to 13.5%. To attain an equitable service for CYP with diabetes mellitus we need to consider interventions at the patient, health care professional, community, and health care system levels.

Stress Hyperglycemia in Children and Adolescents as a Prognostic Indicator for the Development of Type 1 Diabetes Mellitus

Hyperglycemia is a common manifestation in the course of severe disease and is the result of acute metabolic and hormonal changes associated with various factors such as trauma, stress, surgery, or infection. Numerous studies demonstrate the association of adverse clinical events with stress hyperglycemia. This article briefly describes the pathophysiological mechanisms which lead to hyperglycemia under stressful circumstances particularly in the pediatric and adolescent population. The importance of prevention of hyperglycemia, especially for children, is emphasized and the existing models for the prediction of diabetes are presented. The available studies on the association between stress hyperglycemia and progress to type 1 diabetes mellitus are presented, implying a possible role for stress hyperglycemia as part of a broader prognostic model for the prediction and prevention of overt disease in susceptible patients.

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.

The course of diabetes in children, adolescents and young adults: does the autoimmunity status matter?

BACKGROUND

Initial classification of diabetes of young may require revision to improve diagnostic accuracy of different forms of diabetes. The aim of our study was to examine markers of beta-cell autoimmunity in a cohort of young (0-25 years) patients with type 1 diabetes and compare the presentation and course of the disease according to the presence of pancreatic antibodies.

METHODS

Cross-sectional population-based study was performed covering 100% of pediatric (n = 860) and 70% of 18-25 years old adult patients (n = 349) with type 1 diabetes in Lithuania.

RESULTS

No antibodies (GAD65, IA-2, IAA and ICA) were found in 87 (7.5%) cases. Familial history of diabetes was more frequent in those with antibodies-negative diabetes (24.1 vs. 9.4%, p < 0.001). Gestational age, birth weight and age at diagnosis was similar in both groups. Ketosis at presentation was more frequent in patients with autoimmune diabetes (88.1 vs. 73.5%, p < 0.05). HbA1c at the moment of investigation was 8.6 (3) vs. 8.7 (2.2)% in antibodies-negative and antibodies-positive diabetes groups, respectively, p > 0.05. In the whole cohort, neuropathy was found in 8.8% and nephropathy - in 8.1% of cases, not depending on autoimmunity status. Adjusted for age at onset, disease duration and HbA1c, retinopathy was more frequent in antibodies-negative subjects (13.8 vs. 7.8%, p < 0.05).

CONCLUSION

Antibodies-negative pediatric and young adult patients with type 1 diabetes in this study had higher incidence of family history of diabetes, higher frequency of retinopathy, less frequent ketosis at presentation, but similar age at onset, HbA1c, incidence of nephropathy and neuropathy compared to antibodies-positive patients.

Environmental Risk Factors and Type 1 Diabetes: Past, Present, and Future

Type 1 diabetes is an autoimmune condition that results from the destruction of the insulin-producing beta cells of the pancreas. The excess morbidity and mortality resulting from its complications, coupled with its increasing incidence, emphasize the importance of better understanding the causes of this condition. Over the past several decades, a substantive amount of work has been done and, although many advances have occurred in identifying disease-susceptibility genes, there has been a lag in understanding the environmental triggers. Several putative environmental risk factors have been proposed, including infections, dietary factors, air pollution, vaccines, location of residence, family environment and stress. However, most of these factors have been inconclusive, thus supporting the need for further study into the causes of type 1 diabetes.

Global epidemiology of type 1 diabetes in young adults and adults: a systematic review

Background

Although type 1 diabetes (T1D) can affect patients of all ages, most epidemiological studies of T1D focus on disease forms with clinical diagnosis during childhood and adolescence. Clinically, adult T1D is difficult to discriminate from certain forms of Type 2 Diabetes (T2D) and from Latent Autoimmune Diabetes in Adults (LADA).

We searched the information available worldwide on the incidence of T1D among individuals over 15 years of age, and which diagnostic criteria should be used use to qualify T1D in adults. We then studied the variation of T1D incidence with age in adults, and compared it to the incidence in the <15 years-old.

Methods

A systematic review of the literature was performed to retrieve original papers in English, French and Spanish published up to November 6, 2014, reporting the incidence of T1D among individuals aged over 15 years. The study was carried out according to the PRISMA recommendations.

Results

We retrieved information reporting incidence of T1D among individuals aged more than 15 years in 35 countries, and published in 70 articles between 1982 and 2014. Specific anti-beta-cell proteins or C-peptide detection were performed in 14 of 70 articles (20%). The most frequent diagnostic criteria used were clinical symptoms and immediate insulin therapy. Country-to-country variations of incidence in those aged >15 years paralleled those of children in all age groups. T1D incidence was larger in males than in females in 44 of the 54 (81%) studies reporting incidence by sex in people >15 years of age. The overall mean male-to-female ratio in the review was 1.47 (95% CI = 1.33-1.60, SD = 0.49, n = 54, p = <0.0001). Overall, T1D incidence decreased in adulthood, after the age of 14 years.

Conclusions

Few studies on epidemiology of T1D in adults are available worldwide, as compared to those reporting on children with T1D. The geographical variations of T1D incidence in adults parallel those reported in children. As opposed to what is known in children, the incidence is generally larger in males than in females. There is an unmet need to evaluate the incidence of autoimmune T1D in adults, using specific autoantibody detection, and to better analyze epidemiological specificities – if any – of adult T1D.

PROSPERO registration number

CRD42012002369.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-1591-y) contains supplementary material, which is available to authorized users.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

CONCLUSIONS

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

Lower vitamin D status is more common among Saudi adults with diabetes mellitus type 1 than in non-diabetics

Background

Vitamin D deficiency is an increasingly recognized comorbidity in patients with type 1 diabetes mellitus (DMT1), suggesting that vitamin D deficiency might play a role in DMT1. We aimed to determine and compare the vitamin D status of Saudi adults with and without DMT1.

Methods

A total of 60 Saudi adults with DMT1 from the Diabetes Clinics and 60 non-DM, healthy controls were included in the study. The mean age for those with DMT1 was 25.9 ± 16.1 years versus 36.7 ± 3.6 years among the controls. We measured serum 25-hydroxy vitamin D (25OHD), calcium, cholesterol, blood glucose, HDL, and triglycerides and compared the results between the DMT1 group and control subjects.

Results

Both the DMT1 and healthy groups had vitamin D deficiency. The mean levels of 25OHD were significantly lower in the DMT1 adults than in the controls (28.1 ± 1.4 nmol/L versus 33.4 ± 1.6 nmol/L). In the DMT1 adults, 66.7% were mildly, 31.7% moderately, and 3.3% severely vitamin D deficient as compared with 41.7% (mildly), 31.7% (moderately), and 5% (severely) in the control group. Overall, 100% of the DMT1 adults and 78% of the healthy children were vitamin D deficient.

Conclusion

The prevalence of vitamin D deficiency among DMT1 adults was relatively high. Therefore, screening for vitamin D deficiency and supplementation for this population should be warranted.

The emerging global epidemic of type 1 diabetes

Type 1 diabetes mellitus (T1D) can occur at any age, with a peak in incidence around puberty. Classification between T1D and type 2 diabetes becomes more challenging with increasing age of onset of T1D over time develops in genetically predisposed individuals. The main susceptibility is conferred with human leukocyte antigen (HLA) genes. Some of the geographic variation in incidence and familial aggregation is explained by differences in HLA haplotypes. In many populations, the incidence is somewhat higher in males than in females, and a 1.3- to 2.0-fold male excess in incidence after about 15 years of age exists in most populations. The incidence of childhood-onset T1D varies markedly among countries. East Asian and native American populations have low incidences (approximately 0.1-8 per 100 000/year), while the highest rates are found in Finland (>60 per 100 000/year), Sardinia (40 per 100 000/year), and Sweden (47 per 100 000/year). The risk is highest in European-derived populations. About 10 %-20 % of newly diagnosed childhood cases of T1D have an affected first-degree relative. Those with an affected sibling or parent have a cumulative risk of 3 %-7 % up to about 20 years of age, as compared with <1 % in the general population. The cumulative incidence among the monozygotic co-twins of persons with T1D is less than 50 %. Thus, the majority of genetically predisposed people do not develop T1D. Studies assessing temporal trends have shown that the incidence of childhood-onset T1D has increased in all parts of the world. The average relative increase is 3 %-4 % per calendar year. For instance, in Finland, the incidence today is 5 times higher than 60 years ago. At the same time, the age at onset of T1D in children has become younger. It is strongly believed that nongenetic factors are important for the development of T1D and its increase, but the causative evidence is missing. The causes for this increasing trend and current epidemic still remain unknown.

Viruses and vitamin D in the etiology of type 1 diabetes mellitus and multiple sclerosis

Although specific viruses have been associated with autoimmune diseases, none fulfill Koch's criteria of causation. The etiologies of such diseases appear to be complex and multifactorial. For example, one might propose that the etiology of type 1 diabetes mellitus results from a toxic metabolite of nitrosamines during an enteroviral infection. Multiple sclerosis might result from a cascade of events involving several herpes virus infections activated during periods of vitamin D deficiency. We encourage investigators to consider Rotman's sufficient-component causal model when developing hypotheses for testing for the etiology of chronic diseases. Delineating the web of causation may lead to additional strategies for prevention and treatment of several autoimmune diseases.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

The geoepidemiology of type 1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by absolute insulin deficiency resulting from the progressive immune-mediated destruction of pancreatic islet beta cells. It is thought to be triggered by as yet unidentified environmental factors in genetically susceptible individuals, the major genetic contribution coming from loci within the HLA complex, in particular HLA class II. The worldwide incidence of T1D varies by at least 100-fold, being highest in Finland and Sardinia (Italy) and lowest in Venezuela and China. The incidence has been increasing worldwide at an annual rate of approximately 3%. While genetic factors are thought to explain some of the geographic variability in T1D occurrence, they cannot account for its rapidly increasing frequency. Instead, the declining proportion of newly diagnosed children with high-risk genotypes suggests that environmental pressures are now able to trigger T1D in genotypes that previously would not have developed the disease during childhood. Although comparisons between countries and regions with low and high-incidence rates have suggested that higher socioeconomic status and degree of urbanization are among the environmental factors that play a role in the rising incidence of T1D, the findings are too inconsistent to allow firm conclusions. Morbidity and mortality as well as causes of death also show considerable geographic variation. While glycemic control has been identified as a major predictor of the micro- and macrovascular complications of T1D and shows considerable geographical variability, it does not appear to be the only factor involved in the regional differences in complication rates. The role of genetics in susceptibility to nephropathy, retinopathy and other diabetic complications largely remains to be explored.

The incidence of type 1 diabetes is increasing in both children and young adults in Northern Italy: 1984-2004 temporal trends

AIMS/HYPOTHESIS

A shift towards younger age at onset of diabetes in susceptible people has been suggested as a possible explanation for the increasing temporal trend in incidence of type 1 diabetes. We aimed to test this hypothesis by assessing trends in incidence rates in the period 1984-2004 in children and young adults in Northern Italy.

METHODS

The study bases were: (1) children resident in the Province of Turin in the period 1984-2004 and in the remaining areas of the Piedmont Region in the period 1990-2004; and (2) young adults (15-29 years) resident in the Province of Turin in the period 1984-2003. Temporal trends in rates were analysed using Poisson regression models.

RESULTS

A total of 1,773 incident cases were identified. Overall incidence rates/100,000 person-years in the age groups 0-14 and 15-29 years were 11.3 (95% CI 10.7-12.0) and 7.1 (95% CI 6.6-7.7), respectively, with sex differences among young adults only (incidence rate ratio [IRR] in males vs females 1.41 [95% CI 1.20-1.64]). Average annual increases in incidence rates were similar in children and young adults at 3.3% (95% CI 2.5-4.1). Compared with the period 1984-89, in 2000-2004 a 60% higher risk was found in both age 0-14 years (IRR 1.60, 95% CI 1.31-1.95) and 15-29 years (IRR 1.57, 95% CI 1.26-1.96) groups. The Poisson modelling showed no interaction between calendar period and age at onset.

CONCLUSIONS/INTERPRETATION

Incidence of type 1 diabetes in Northern Italy is increasing over time in both children and young adults, not supporting the hypothesis of a shift towards younger age as the main explanation for the increasing temporal trend in children.

Does social-economical transformation influence the incidence of type 1 diabetes mellitus? A Polish example

BACKGROUND

The dramatic increase in the incidence of diabetes mellitus type 1 (DMT1) in all countries of Central and Eastern Europe seems to be correlated with the rapid transformations of the political, economical, and social conditions. The aim of this study was to analyze the increase of DMT1 incidence vs. changes of parameters describing economical conditions, medical care standards, and level of hygiene.

MATERIALS AND METHODS

The study was based on the Upper Silesia, Poland, prospective register of DMT1 cases, a part of the EURODIAB program. The analyzed parameters were number of salmonellosis, taeniasis, diarrhea, and diarrhea in children aged 0 - 2 yr, alimentary toxicosis, neonatal mortality rate, average male and female life expectancy, gross domestic product (GDP), and accessibility to the water supply and sewage lines.

RESULTS

The dynamics of incidence increase has been very high: from 4.71/100 000 (1989) to 15.20/100 000 (2002); average increase per year is 7.52%. The statistically significant positive associations between DMT1 incidence and average male and female life expectancy, GDP, and accessibility of the water supply and sewage systems as well as the negative association for both neonatal mortality rate and nursery attendance were observed. No significant correlation was found between DMT1 and incidence rates of chosen diseases.

CONCLUSIONS

Currently, Poland and its part, Upper Silesia, belong to regions with high DMT1 incidence in children. The change from low to high incidence of DMT1 over the past 14 yr corresponded to profound social and economical transformations. Our observations confirm the importance of environmental factors in the aetiopathogenesis of DMT1. The state of hygiene and the state of the health of the society influence its susceptibility to DMT1.

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

AIMS

To explore how socioeconomic factors and population density may contribute to the geographical variation of incidence of Type 1 diabetes in children in south-eastern Sweden.

METHOD

All children diagnosed with Type 1 diabetes in south-eastern Sweden during 1977-2001 were defined geographically to their place of residence and were allocated x and y coordinates in the national grid. The population at risk and socioeconomic data were aggregated in 82,000 200-m squares and geocoded likewise. A socioeconomic index was calculated using a signed chi(2) method. Rural-urban gradients were defined by overlay analysis in a geographic information system.

RESULTS

The incidence during the past 25 years has been rising steadily, particularly in the last 6 years. The incidence was highest in areas with a high proportion of small families, of families with a high family income and better education, and this was found both at the time of diagnosis and at the time of birth. In the rural-urban analysis, the lowest incidence was found in the urban area with > 20,000 inhabitants, where there was also a higher frequency of deprivation.

CONCLUSIONS

Our findings indicate that geographical variations in incidence rates of Type 1 diabetes in children are associated with socioeconomic factors and population density, although other contributing factors remain to be explained.

Changing geographical distribution of diabetes mellitus type 1 incidence in Austrian children 1989--2005

OBJECTIVES

We investigated whether the significant spatial West/East trend of incidence of Diabetes mellitus Type 1 in Austrian children changed between 1989 and 2005. Additionally we tested, whether population density and mean body mass index of newborns is associated with incidence.

STUDY DESIGN AND SETTING

All newly diagnosed cases aged 0-14 years in Austria (n = 2644), prospectively registered from 1989 to 2005 were allocated to 99 districts. Ecological regression and analysis was done by Bayesian hierarchical models including spatially correlated risks.

RESULTS

In Austria, the incidence rose from 9.1/100.000 in 1989--1994 to 14.9/100.000 in 2001--2005. The spatial trend in the period 1989--1995, showing high incidence in the Eastern parts of Austria, disappeared. In the period 2001--2005 a significant inverse negative association of population density with incidence was found. Mean body mass index of newborns in the Austrian population is significantly positively associated with incidence.

CONCLUSION

The observation of higher incidence in rural areas in Austria during recent years may reflect a lower exposure to protective environmental factors, e.g. infections early in life. The observed association with the BMI in newborns indicates that neonatal or prenatal metabolic aspects may modulate the risk for childhood diabetes. We cannot explain the change in the spatial distribution of incidence.

The age at diagnosis of type 1 diabetes continues to decrease in Belgian boys but not in girls: a 15-year survey

BACKGROUND

The age at clinical onset of type 1 diabetes is decreasing. Preliminary Belgian data suggested that this anticipation occurred preferentially in boys. We investigated whether this gender-specific anticipation could be confirmed over a 15-year observation period.

METHODS

In Antwerp, we studied incidence trends between 1989 and 2003 in 746 type 1 diabetic patients under age 40. For 2928 antibody-positive patients diagnosed nationwide during the same period, age at diagnosis was analysed according to gender and calendar year.

RESULTS

In Antwerp, the incidence of type 1 diabetes under age 15 increased significantly with time from 10.9/100 000/year in 1989-1993 to 15.8/100 000/year in 1999-2003 (p = 0.008). The rising incidence in children was largely restricted to boys under age 10 where the incidence more than doubled during the 15-year period (6.8/100 000/year in 1989-1993 vs 17.2/100 000/year in 1999-2003; p < 0.001). Such an increase was not found in girls under age 10 (p = 0.54). This selective trend toward younger age at diagnosis in boys was confirmed in the larger group of Belgian patients where the median age at diagnosis decreased in boys-but not in girls-from 20 years in 1989-1993 to 15 years in 1999-2003 (p < 0.001).

CONCLUSIONS

Over a 15-year observation period, a selective anticipation of clinical onset of type 1 diabetes was found in boys but not in girls. This suggests that an environmental factor may preferentially accelerate the sub-clinical disease process in young boys.

An update on the etiology and epidemiology of diabetes mellitus

Diabetes mellitus is one of the most common endocrine disorders affecting almost 6% of the world's population. The number of diabetic patients will reach 300 million in 2025 (International Diabetes Federation, 2001). More than 97% of these patients will have type II diabetes. The projected increase in the number of diabetic patients will strain the capabilities of healthcare providers the world over. Thus it is of paramount importance to revisit the causes and epidemiology of diabetes mellitus. Diabetes mellitus is caused by both environmental and genetic factors. The environmental factors that may lead to the development of diabetes mellitus include physical inactivity, drugs and toxic agents, obesity, viral infection, and location. While type I diabetes is not a genetically predestined disease, an increased susceptibility can be inherited. Genetic susceptibility plays a crucial role in the etiology and manifestation of type II diabetes, with concordance in monozygotic twins approaching 100%. Genetic factors may have to be modified by environmental factors for diabetes mellitus to become overt. An individual with a susceptible gene may become diabetic if environmental factors modify the expression of these genes. Since there is an increase in the trend at which diabetes prevail, it is evident that environmental factors are playing a more increasing role in the cause of diabetes mellitus. The incidence of type I diabetes ranged from 1.9 to 7.0/100,000/yr in Africa, 0.13 to 10/100,000/yr in Asia, approximately 4.4/100,000/yr in Australasia, 3.4 to 36/100,000/yr in Europe, 2.62 to 20.18/100,000/yr in the Middle East, 7.61 to 25.7/100,000/yr in North America, and 1.27 to 18/100,000/yr in South America. The epidemiology of type II diabetes is equally bleak. The prevalence of type II diabetes ranged from 0.3 to 17.9% in Africa, 1.2 to 14.6% in Asia, 0.7 to 11.6% in Europe, 4.6 to 40% in the Middle East, 6.69 to 28.2% in North America, and 2.01 to 17.4% in South America.

Secular trends, disease maps and ecological analyses of the incidence of childhood onset Type 1 diabetes in Northern Ireland, 1989-2003

AIMS

To investigate secular trends in the incidence of Type 1 diabetes in Northern Ireland over the period 1989-2003. To highlight geographical variations in the incidence of Type 1 diabetes by producing disease maps and to compare incidence rates by relevant area characteristics.

METHODS

New cases of Type 1 diabetes in children aged 0-14 years in Northern Ireland were prospectively registered from 1989 to 2003. Standardized incidence rates were calculated and secular trends investigated. Bayesian methodology was used to produce maps of disease incidence using small geographical areas (582 electoral wards). Ecological analyses were conducted using Poisson regression to investigate incidence rates by area characteristics at a finer geographical subdivision (5022 census output areas).

RESULTS

In Northern Ireland during 1989-2003, there were 1433 new cases, giving a directly standardized incidence rate of 24.7 per 100,000 person-years. This incidence rate increased by a mean of 4.2% per annum. Disease maps highlighted higher incidence rates in the predominately rural north-east of the province and lower incidence rates in the urban areas around Belfast in the east and Derry in the north-west of the province. Ecological analysis identified higher incidence in rural areas (P < 0.001), areas with low migration rates (P = 0.002), affluent areas (P < 0.0001), sparsely populated areas (P = 0.0001) and remote areas (P = 0.005). CONCLUSIONS In Northern Ireland the incidence of Type 1 diabetes is increasing. The observed higher incidence in rural, affluent, sparsely populated and remote areas may reflect a reduced or delayed exposure to infections in these areas.

Higher incidence of childhood-onset type 1 diabetes mellitus in remote areas: a UK regional small-area analysis

AIMS/HYPOTHESIS

We investigated the association between the incidence of type 1 diabetes mellitus and remoteness (a proxy measure for exposure to infections) using recently developed techniques for statistical analysis of small-area data.

SUBJECTS, MATERIALS AND METHODS

New cases in children aged 0 to 14 years in Northern Ireland were prospectively registered from 1989 to 2003. Ecological analysis was conducted using small geographical units (582 electoral wards) and area characteristics including remoteness, deprivation and child population density. Analysis was conducted using Poisson regression models and Bayesian hierarchical models to allow for spatially correlated risks that were potentially caused by unmeasured explanatory variables.

RESULTS

In Northern Ireland between 1989 and 2003, there were 1,433 new cases of type 1 diabetes, giving a directly standardised incidence rate of 24.7 per 100,000 person-years. Areas in the most remote fifth of all areas had a significantly (p=0.0006) higher incidence of type 1 diabetes mellitus (incidence rate ratio=1.27 [95% CI 1.07, 1.50]) than those in the most accessible fifth of all areas. There was also a higher incidence rate in areas that were less deprived (p<0.0001) and less densely populated (p=0.002). After adjustment for deprivation and additional adjustment for child population density the association between diabetes and remoteness remained significant (p=0.01 and p=0.03, respectively).

CONCLUSIONS/INTERPRETATION

In Northern Ireland, there is evidence that remote areas experience higher rates of type 1 diabetes mellitus. This could reflect a reduced or delayed exposure to infections, particularly early in life, in these areas.

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.

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.

Residual beta-cell function and male/female ratio are higher in incident young adults than in children: the registry of type 1 diabetes of the province of Turin, Italy, 1984-2000

OBJECTIVE

The hypothesis of age-dependent variations in epidemiologic and clinical features at onset of type 1 diabetes has been assessed in the registry of the province of Turin, Italy.

RESEARCH DESIGN AND METHODS

The study base is the population 0-29 years of age of the province of Turin, in the period from 1984 to 2000. Islet cell antibody (ICA), GAD antibody (GADA), antibodies to protein tyrosine phosphatase (IA2), and C-peptide were measured in subgroups of the cohort.

RESULTS

One thousand fifty-six incident cases have been identified (completeness of ascertainment 98.1%). Rates per 100,000 person-years were similar in males and females in the age-group 0-14 years (10.7, 95% CI 9.5-12.0 vs. 9.8, 8.6-11.1). In the age-group 15-29 years, males had higher risk than females (7.7, 6.9-8.6 vs. 5.3, 4.6-6.1; rate ratio, 1.46, 95% CI 1.23-1.74; P = 0.00002). Fasting plasma C-peptide values (n = 575) were twofold lower in the age-group 0-14 years than in the age-group 15-29 years (0.10 vs. 0.23 nmol/l; P < 0.0001). Frequencies of ICA and IA2 positivities (n = 183) decreased with increasing age, whereas frequency of GADA positivity increased. Idiopathic cases were 12.6% and had higher mean values of fasting (0.28 vs. 0.14 nmol/l; P = 0.043) and stimulated C-peptide (0.59 vs. 0.34 nmol/l; P = 0.05). In logistic regression analyses, subjects with fasting C-peptide values in the upper quartile had higher likelihood of being older (odds ratio 1.20 for year, 95% CI 1.11-1.28), ICA negative (0.26, 0.10-0.70), and female (1.29, 0.48-3.42).

CONCLUSIONS

This study shows 1) sex differences in incidence rates in young adults; 2) better preserved beta-cell function in young adults, in idiopathic cases (12%), and in ICA-negative cases; and 3) lower frequencies of ICA and IA2 positivities and higher frequency of GADA positivity in young adults than in children.