Prenatal and early life factors and type 1 diabetes.

BACKGROUND: The prevalence of type 1 diabetes is increasing worldwide, suggesting that unknown environmental factors are becoming increasingly important in its pathogenesis. AIM: The aim of the study was to investigate the possible role of a number of prenatal and perinatal factors in the aetiology of type 1 diabetes. METHODS: Mothers of patients diagnosed with type 1 diabetes (cases) and mothers of children born on the same day and of the same sex as type 1 diabetes patients (controls) were interviewed on a number of prenatal and perinatal factors of interest. RESULTS: Hand washing prior to eating, frequency of bathing and total stress score were found to be positively associated with the development of type 1 diabetes on univariate analyses. Hand-washing prior to eating and frequency of house cleaning were independently associated with an increased risk of type 1 diabetes, whilst getting dirty was associated with a reduced risk in multivariate analyses. There was no association of type 1 diabetes to removing of outdoor shoes indoors or to the age of first attendance to school or pre-school. There were also no significant associations to parental smoking, parental age, birth order, infant feeding, antibiotic use, mode of delivery or birth weight. CONCLUSION: Our data suggest that factors that affect the skin or gut microbiome might be more important than infections or factors affecting the microbiome at other sites.

Why is the Incidence of Type 1 Diabetes Increasing?

Type 1 diabetes is a condition that can lead to serious long-term complications and can have significant psychological and quality of life implications. Its incidence is increasing in all parts of the world, but the reasons for this are incompletely understood. Genetic factors alone cannot explain such a rapid increase in incidence; therefore, environmental factors must be implicated. Lifestyle factors have been classically associated with type 2 diabetes. However, there are data implicating obesity and insulin resistance to type 1 diabetes as well (accelerator hypothesis). Cholesterol has also been shown to be correlated with the incidence of type 1 diabetes; this may be mediated by immunomodulatory effects of cholesterol. There is considerable interest in early life factors, including maternal diet, mode of delivery, infant feeding, childhood diet, microbial exposure (hygiene hypothesis), and use of anti-microbials in early childhood. Distance from the sea has recently been shown to be negatively correlated with the incidence of type 1 diabetes. This may contribute to the increasing incidence of type 1 diabetes since people are increasingly living closer to the sea. Postulated mediating mechanisms include hours of sunshine (and possibly vitamin D levels), mean temperature, dietary habits, and pollution. Ozone, polychlorinated biphenyls, phthalates, trichloroethylene, dioxin, heavy metals, bisphenol, nitrates/nitrites, and mercury are amongst the chemicals which may increase the risk of type 1 diabetes. Another area of research concerns the role of the skin and gut microbiome. The microbiome is affected by many of the factors mentioned above, including the mode of delivery, infant feeding, exposure to microbes, antibiotic use, and dietary habits. Research on the reasons why the incidence of type 1 diabetes is increasing not only sheds light on its pathogenesis but also offers insights into ways we can prevent type 1 diabetes.

Incidence of type 1 diabetes and distance from the sea: A descriptive epidemiological study.

BACKGROUND: Increasingly, environmental factors are being shown to play a role in the etiology of type 1 diabetes (T1D). One geographical feature that exerts a major effect on climate but whose relationship with T1D incidence has not been studied is distance from the sea. This study investigated any possible relationship between distance from the sea and the incidence of T1D. METHODS: Spearman correlation analysis was performed to investigate the relationship between the incidence of T1D (determined using data from the DiaMond Project) and distance from the sea. This was followed by multivariate analyses to adjust for potential cofounders. RESULTS: A significant negative association was found between T1D incidence and shortest distance from sea (r = -0.251, P = 0.01235), mean hours of sunshine (r = -0.325, P = 0.002), and mean temperature (r = -0.224, P = 0.046), and a positive association was found between T1D incidence and latitude (r = 0.434, P = 0.0001). Multivariate analysis (generalized linear model) showed that both distance from the sea and latitude were independently associated with the incidence of T1D. The association of distance from sea and the incidence of T1D remained significant even after adjusting for mean temperature (P = 0.002) and mean hours of sunshine (P = 0.005). CONCLUSIONS: The data show that there is a negative correlation between distance from the sea and the incidence of T1D, which was independent of latitude, mean temperature, and mean hours of sunshine. This suggests that environmental factors associated with climatic conditions may influence the risk of T1D.