Type 1 diabetes in sardinia is not linked to nitrate levels in drinking water

Nitrate induces a type 1 diabetic profile in alligator hatchlings

Type 1 diabetes (T1D) is a chronic autoimmune disease that affects 1 in 300 children by age 18. T1D is caused by inflammation-induced loss of insulin-producing pancreatic beta cells, leading to high blood glucose and a host of downstream complications. Although multiple genes are associated with T1D risk, only 5% of genetically susceptible individuals actually develop clinical disease. Moreover, a growing number of T1D cases occur in geographic clusters and among children with low risk genotypes. These observations suggest that environmental factors contribute to T1D etiology. One potential factor, supported primarily by epidemiological studies, is the presence of nitrate and nitrite in drinking water. To test this hypothesis, female hatchling alligators were exposed to environmentally relevant concentrations of nitrate in their tank water (reference, 10mg/L, or 100mg/L NO₃-N) from hatch through 5 weeks or 5 months of age. At each time point, endpoints related to T1D were investigated: plasma levels of glucose, triglycerides, testosterone, estradiol, and thyroxine; pancreas, fat body, and thyroid weights; weight gain or loss; presence of immune cells in the pancreas; and pancreatic beta cell number, assessed by antibody staining of nkx6.1 protein. Internal dosing of nitrate was confirmed by measuring plasma and urine nitrate levels and whole blood methemoglobin. Cluster analysis indicated that high nitrate exposure (most animals exposed to 100mg/L NO3-N and one alligator exposed to 10mg/L NO3-N) induced a profile of endpoints consistent with early T1D that could be detected after 5 weeks and was more strongly present after 5 months. Our study supports epidemiological data correlating elevated nitrate with T1D onset in humans, and highlights nitrate as a possible environmental contributor to the etiology of T1D, possibly through its role as a nitric oxide precursor.

Association of type 1 diabetes and concentrations of drinking water components in Newfoundland and Labrador, Canada

OBJECTIVE

To determine the association between drinking water quality and rates of type 1 diabetes in the Newfoundland and Labrador (NL) population, which has one of the highest incidences of type 1 diabetes reported globally.

RESEARCH DESIGN AND METHODS

The study used a community-based, case-control design. We first calculated incidence rates of type 1 diabetes at the provincial, regional and community levels. The connection between incidence rates and components in public water supplies were then analyzed in three ways: to evaluate differences in water quality between communities with and without incident cases of type 1 diabetes, and to analyze the relationship between water quality and incidence rates of type 1 diabetes at both the community and regional levels.

RESULTS

The provincial incidence of type 1 diabetes was 51.7/100 000 (0-14 year age group) for the period studied. In the community-based analysis, there were significant associations found between higher concentrations of arsenic (β=0.268, P=0.013) and fluoride (β=0.202, P=0.005) in drinking water and higher incidence of type 1 diabetes. In the regional analysis, barium (β=-0.478, P=0.009) and nickel (β=-0.354, P=0.050) concentrations were negatively associated with incidence of type 1 diabetes.

CONCLUSIONS

We confirmed the high incidence of type 1 diabetes in NL. We also found that concentrations of some components in drinking water were associated with higher incidence of type 1 diabetes, but no component was found to have a significant association across the three different levels of analysis performed.

Type 1 diabetes in Sardinia: facts and hypotheses in the context of worldwide epidemiological data

Type 1 diabetes (T1D) results from an autoimmune destruction of insulin-producing beta cells that requires lifelong insulin treatment. While significant advances have been achieved in treatment, prevention of complications and quality of life in diabetic people, the identification of environmental triggers of the disease is far more complex. The island of Sardinia has the second highest incidence of T1D in the world (45/100,000), right after Finland (64.2/100,000). The genetic background as well as the environment of the island's inhabitants makes it an ideal region for investigating environmental, immunological and genetic factors related to the etiopathogenesis of T1D. Several epidemiological studies, conducted over the years, have shown that exposures to important known environmental risk factors have changed over time, including nutritional factors, pollution, chemicals, toxins and infectious diseases in early life. These environmental risk factors might be involved in T1D pathogenesis, as they might initiate autoimmunity or accelerate and precipitate an already ongoing beta cell destruction. In terms of environmental factors, Sardinia is also particular in terms of the incidence of infection with Mycobacterium avium paratuberculosis (MAP) that recent studies have linked to T1D in the Sardinian population. Furthermore, the unique geochemical profile of Sardinia, with its particular density of heavy metals, leads to the assumption that exposure of the Sardinian population to heavy metals could also affect T1D incidence. These factors lead us to hypothesize that T1D incidence in Sardinia may be affected by the exposure to multifactorial agents, such as MAP, common viruses and heavy metals.

Nitrate-nitrite-nitrosamines exposure and the risk of type 1 diabetes: A review of current data

The potential toxic effects of nitrate-nitrite-nitrosamine on pancreatic β cell have remained a controversial issue over the past two decades. In this study, we reviewed epidemiological studies investigated the associations between nitrate-nitrite-nitrosamines exposure, from both diet and drinking water to ascertain whether these compounds may contribute to development of type 1 diabetes. To identify relevant studies, a systematic search strategy of PubMed, Scopus, and Science Direct was conducted using queries including the key words “nitrate”, “nitrite”, “nitrosamine” with “type 1 diabetes” or “insulin dependent diabetes mellitus”. All searches were limited to studies published in English. Ecologic surveys, case-control and cohort studies have indicated conflicting results in relation to nitrate-nitrite exposure from drinking water and the risk of type 1 diabetes. A null, sometimes even negative association has been mainly reported in regions with a mean nitrate levels < 25 mg/L in drinking water, while increased risk of type 1 diabetes was observed in those with a maximum nitrate levels > 40-80 mg/L. Limited data are available regarding the potential diabetogenic effect of nitrite from drinking water, although there is evidence indicating dietary nitrite could be a risk factor for development of type 1 diabetes, an effect however that seems to be significant in a higher range of acceptable limit for nitrate/nitrite. Current data regarding dietary exposure of nitrosamine and development of type 1 diabetes is also inconsistent. Considering to an increasing trend of type 1 diabetes mellitus (T1DM) along with an elevated nitrate-nitrite exposure, additional research is critical to clarify potential harmful effects of nitrate-nitrite-nitrosamine exposure on β-cell autoimmunity and the risk of T1DM.

Zinc and Other Metals Deficiencies and Risk of Type 1 Diabetes: An Ecological Study in the High Risk Sardinia Island

Background

Type 1 diabetes incidence presents a decreasing gradient in Europe from the Nordic countries to the Mediterranean ones. Exception to this gradient is represented by Sardinia, the second largest Mediterranean island whose population shows the highest incidence in Europe, after Finland. The genetic features of this population have created a fertile ground for the epidemic of the disease, however, as well as being strikingly high, the incidence rate has suddenly presented a continuous increase from the ‘50s, not explainable by accumulation of new genetic variants. Several environmental factors have been taken into account, possibly interacting with the genetic/epigenetic scenario, but there are no strong evidences to date.

Methods

The present study investigated the hypothesis that geochemical elements could create permissive environmental conditions for autoimmune diabetes. An ecological analysis was performed to test possible correlations between the values of eight elements in stream sediments and type 1 diabetes incidence rate in Sardinia.

Results

Analyses revealed negative associations between elements, such as Co, Cr, Cu, Mn, Ni, Zn, and type 1 diabetes incidence.

Conclusions

The results suggest a possible protective role of some elements against the onset of the disease.

Type 1 diabetes mellitus and components in drinking water and diet: a population-based, case-control study in Prince Edward Island, Canada

OBJECTIVE

To determine the relationship between the risk of type 1 diabetes (T1D) and daily intake of drinking water and dietary components, including nitrate, nitrite, and nitrosamines, during the year prior to diagnosis.

METHODS

Controls (n = 105) were matched by age at diagnosis and sex to T1D cases (n = 57) newly diagnosed during 2001-2004. Food consumption was assessed using a food frequency questionnaire. Locally available samples of foods were tested for nitrate, nitrite, and nitrosamine concentrations. Water consumption was determined through an additional questionnaire, and water samples were taken from homes and tested for routine chemical components, including nitrate.

RESULTS

After controlling for age, age, sex, and daily energy intake, nitrate intake from food sources showed a non-significant positive trend (odds ratios and 95% confidence intervals for quartiles = 1.00, 1.63 (0.58, 4.63), 1.71 (0.54, 5.40), 3.02 (0.78, 11.74); p for trend = 0.13). Nitrite and nitrosamine intake were not related to T1D risk (p for trend = 0.77 and 0.81, respectively). When food and water components were combined, zinc and calcium intakes were marginally and inversely related to T1D risk (p for trend = 0.07 and 0.06, respectively). After further model adjustment of possible confounders and significant risk factors, an increased intake of caffeine marginally increased the risk of T1D (p = 0.07).

CONCLUSION

Dietary components from both food and water sources may influence the risk of developing T1D in young persons.

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 Sardinian way to type 1 diabetes

Sardinia and Finland are the "hottest" areas for type 1 diabetes mellitus (T1DM) worldwide. Its genetic and epidemiological background make Sardinia an ideal region for investigating environmental, immunological, and genetic factors related to the etiopathogenesis of T1DM. Consequently, in 1990, the Insulin-Dependent Diabetes Mellitus Sardinia Project was launched in order to map the geographical distribution of T1DM in the island and to investigate preclinical phases of T1DM in a large cohort of people genetically at risk. The final goal would be to design models of prediction and to formulate safe preventive measures, especially addressed to the general population living in areas at high risk.

Nitrate in community water supplies and risk of childhood type 1 diabetes in Sardinia, Italy

We tested the hypothesis of an association between childhood type 1 diabetes (T1D) risk and nitrate concentration in drinking water in Sardinia, Italy, using Poisson regression analysis. Childhood T1D risk showed an inverse trend with increasing quartile of nitrate level in the total population and among men. A nitrate concentration in drinking water below 10 mg/l is unlikely to account for the spatial variation in childhood T1D incidence.

Geographical mapping of type 1 diabetes in children and adolescents in south east Sweden

STUDY OBJECTIVE

As earlier studies have shown space-time clusters at onset of type 1 diabetes in the south east region of Sweden we investigated if there also has been any geographical clusters of diabetes in this region.

DESIGN

The place of residence (coordinates) at the time of diagnosis were geocoded in a geographical information system (GIS). All children diagnosed with type 1 diabetes up to 16 years of age at diagnosis between 1977-1995 were included. The population at risk was obtained directly from the population registry for the respective years and geographical area levels.

SETTING

South east region of Sweden containing 5 counties, 49 municipalities, and 525 parishes.

MAIN RESULTS

A significant geographical variation in incidence rate were found between the municipalities (p<0.001) but not between the counties. The variation became somewhat weaker when excluding the six largest municipalities (p<0.02). In municipalities with increased risk (>35.1/100 000) the major contribution comes from children in age group 6-10 years of age at diagnosis. There were no obvious differences between the age groups in municipalities with decreased risk (<20.1/100 000). Boys and girls had about the same degree of geographical variation.

CONCLUSIONS

Apart from chance, the most probable explanation for the geographical variation in the risk for children and adolescents to develop type 1 diabetes between the municipalities in the region is that local environmental factors play a part in the process leading to the disease.

Type 1 diabetes among sardinian children is increasing: the Sardinian diabetes register for children aged 0-14 years (1989-1999)

OBJECTIVE

The Sardinian type 1 diabetes register represented the basis to determine the most recent trends and the age distribution of type 1 diabetes incidence among Sardinians <15 years of age during 1989-1999. Part of the data (1989-1998) has been already published by the EURODIAB Group with a lower completeness of ascertainment (87%). The geographical distribution of type 1 diabetes risk was also investigated.

RESEARCH DESIGN AND METHODS

The new cases of type 1 diabetes in children aged 0-14 years in Sardinia were prospectively registered from 1989 to 1999 according to the EURODIAB ACE criteria. The completeness of ascertainment calculated applying the capture-recapture method was 91%. Standardized incidence rates and 95% CI were calculated assuming the Poisson distribution. Trend of type 1 diabetes incidence was analyzed using the Poisson regression model. Maps of the geographical distribution of type 1 diabetes risk for the whole time period and separately for 1989-1994 and 1995-1999 were produced applying a Bayesian method.

RESULTS

A total of 1214 type 1 diabetic patients were registered yielding to an overall age- and sex-standardized incidence rate of 38.8/100000 (95% CI 36.7-41.1). There was a male excess with an overall male-to-female ratio of 1.4 (1.3-1.8). The increase of incidence during the 11 years analyzed was statistically significant (P = 0.002) with a yearly increasing rate of 2.8% (1.0-4.7). No evidence of an effect of age and sex on this trend has been found. The geographical distribution of type 1 diabetes relative risk (RR) showed that the highest risk areas are located in the southern and central-eastern part of the island and the lowest risk in the northeastern part, even if most of these differences were not statistically significant. This geographical distribution seemed to remain mainly the same between 1989-1994 and 1995-1999.

CONCLUSIONS

The homogeneity of diabetes risk and the increase of incidence over the age-groups in the Sardinian population stress the role of an environmental factor uniformly distributed among the genetically high-risk Sardinians.

Zinc and nitrate in the ground water and the incidence of Type 1 diabetes in Finland

AIMS

In Finland, the risk of childhood Type 1 diabetes varies geographically. Therefore we investigated the association between spatial variation of Type 1 diabetes and its putative environmental risk factors, zinc and nitrates.

METHODS

The association was evaluated using Bayesian modelling and the geo-referenced data on diabetes cases and population.

RESULTS

Neither zinc nor nitrate nor the urban/rural status of the area had a significant effect on the variation in incidence of childhood Type 1 diabetes.

CONCLUSIONS

The results showed that although there was no significant difference in incidence between rural and urban areas, there was a tendency to increasing risk of Type 1 diabetes with the increasing concentration of NO3 in drinking water. The fact that no significant effect was found may stem from the aggregated data being too crude to detect it.

Bayesian approach to study the temporal trend and the geographical variation in the risk of type 1 diabetes. The Sardinian Conscript Type 1 Diabetes Registry

BACKGROUND

A previous analysis of the Sardinian Conscript Type 1 Diabetes Registry indicated an abrupt increase in the risk for type 1 diabetes (T1D) among Sardinian male cohorts starting from the 1946 one.

OBJECTIVE

The aim of this study was to update the point prevalence of T1D among Sardinian male army conscripts aged 18 yr from 1992 to 1997 described in the previous survey and to update its secular trend. It also looked at the geographical distribution of prevalence.

SUBJECTS AND METHODS

All male Italian citizens must appear before the Conscript Board for a clinical examination prior to military service. T1D patients are rejected with T1D listed as the reason. We examined, retrospectively, a total of 83807 Sardinian males aged 18, born between 1 January 1974 and 31 December 1979. They virtually represent the whole Sardinian population of that age and sex.

RESULTS

A total of 307 subjects with T1D were identified. T1D point prevalence for the birth cohorts 1974-1979 was 3.66/1000 (95% CI 3.28-4.09). Bayesian analysis of the geographical distribution of prevalence shows the highest rate in the Southern part of the island (Cagliari province) and the lowest in the north-western part (Sassari province). A similar picture was produced by data from the Eurodiab Registry in Sardinia (1989 ongoing). No significant temporal trend of prevalence was seen in the 6 yr examined in the current study; pooling these recent birth cohorts with the previous ones, the increasing trend of prevalence was confirmed.

CONCLUSIONS

Our data confirmed the South to North gradient of T1D and the progressive increase of T1D risk among males in Sardinia.

Nutritional risk predictors of beta cell autoimmunity and type 1 diabetes at a young age

Type 1 diabetes is an immune-mediated disease characterized by a preclinical prodrome during which beta cell autoimmunity proceeds at a variable rate. Large geographic differences and a conspicuous increase in incidence, especially among young children since the 1950s, and the relatively low concordance in identical twins are factors that favor a critical role of environmental factors in the etiology of this disease. Only approximately 5% or fewer subjects with HLA-conferred genetic susceptibility to type 1 diabetes actually develop the clinical disease. Breastfeeding, nicotinamide, zinc, and vitamins C, D, and E have been reported as possibly protecting against type 1 diabetes, whereas N-nitroso compounds, cow milk, increased linear growth, and obesity may increase the risk. Thus far, only the significance of infant feeding, cow milk, and vitamin D have been studied in both case-control and cohort settings. The major shortcoming of most studies done so far is that only single dietary exposures have been assessed at single time points. Putative nutritional and other confounding factors have received little attention as have the limitations of the dietary methods used. There is little firm evidence of the significance of nutritional factors in the etiology of type 1 diabetes. The availability of good markers of preclinical type 1 diabetes and of genetic risk have decreased the sample sizes needed and made longitudinal cohort studies of the assessment of children's diets feasible.

Acidic drinking water and risk of childhood-onset type 1 diabetes

OBJECTIVE

To estimate the associations of acidity and concentration of selected minerals in household tap water with the risk of type 1 diabetes.

RESEARCH DESIGN AND METHODS

We designed a population-based case-control study with 64 cases of type 1 diabetes and 250 randomly selected control subjects. Acidity, color, and mineral content were measured in tap water from each participant's household.

RESULTS

Tap water pH 6.2-6.9 was associated with a fourfold higher risk of type 1 diabetes compared with pH > or =7.7 (OR 3.73, 95% CI 1.52-9.15). This result was similar after exclusion of individuals with the highly protective HLA-DQB1*0602 allele, but adjustment for maternal education, urban/rural residence, sex, and age tended to strengthen the estimated association. Higher tap water concentration of zinc was associated with lower risk of type 1 diabetes after adjustment for pH and other possible confounders, but the overall association was strictly not significant.

CONCLUSIONS

These results suggest the possibility that quality of drinking water influences the risk of type 1 diabetes. The possible mechanisms by which water acidity or mineral content may be involved in the etiology of type 1 diabetes remain unknown, but the mechanisms are most likely indirect and may involve an influence on survival of microorganisms in the water.

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.