Why is the Incidence of Type 1 Diabetes Increasing?

Abstract

: 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). Population cholesterol has also been shown to be correlated with the incidence of type 1 diabetes; this may be mediated by the 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 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 into 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.

Young‐onset diabetes patients in Thailand: Data from Thai Type 1 Diabetes and Diabetes diagnosed Age before 30 years Registry, Care and Network (T1DDAR CN)

“…However, in Finland, a country with a high incidence of type 1 diabetes, the incidence of type 1 diabetes increased during 1953-2006, but since 2006, that trend has been decreasing 15 . Several factors; for example, obesity (accelerator hypothesis), gut microbiome, exposure to several chemicals and early life factors, including maternal diet, mode of delivery, infant feeding, childhood diet and microbial exposure (hygiene hypothesis), might contribute to the increasing incidence of type 1 diabetes in certain populations 16 . The present study found that type 1 diabetes (62.6%) and type 2 diabetes (30.7%) accounted for the majority of cases with young-onset diabetes.…”

Maternal and Childhood Diet and Human Type 1 Diabetes Risk

“…On the other hand, sulphur-containing amino acids are associated with increased adiposity [30], whilst branched-chain and aromatic amino acids predict insulin resistance in young adults [31]. Both obesity and insulin resistance have been linked to type 1 diabetes [12]. Likewise, there may be differences in the biological effects of various monounsaturated fatty acids [32].…”

“…Dietary factors have been proposed as one potential mechanism [9]. Dietary factors have profound effects on the gut microbiome [10,11], which is thought to play an important role in the pathogenesis of type 1 diabetes [12]. Dietary factors in childhood can also induce islet cell autoimmunity [13,14], possibly mediated by microbiome changes [15,16].…”

Multi-Faceted Influence of Obesity on Type 1 Diabetes in Children – From Disease Pathogenesis to Complications

“…The pathogenesis of T1D is very complex and depends on numerous heterogeneous aspects ( 19 ). Commonly mentioned are genetic, environmental, immune and recently added are microbiome factors ( Table 1 ).…”