Understanding the type 1 diabetes (T1D) etiology, the second most frequent autoimmune disease in childhood will allow the designing of strategies to avoid or delay the T1D onset and to maintain control if developed. Our group has focused on the relationship between perinatal history, diet, and gut microbiota structure in Mexican children with genetic predisposition or developed T1D.
After gene sequencing, we found that newly diagnosed T1D cases had high levels of Bacteroides (p < 0.004), whereas in healthy children the dominant genus was Prevotella. Children with T1D treated for ≥2 years had levels of Bacteroides and Prevotella with a trend to those in healthy children. The differences in microbiota between healthy and newly diagnosed children could be attributed to the autoimmune process. However, subsequent changes in the microbiota could depend on factors such as diet. We evaluated diet and microbiota in children with T1D, during the first year after diagnosis. T1D children decreased intake of energy (p=0.028), protein (p=0.012), and saturated fat (p=0.031) from baseline to 3 months, without posterior changes. Bacteroides proportion increased in the first month and tended to decrease at 9 months (p > 0.05) and was positively correlated with saturated fat (β = 3.70, p=0.009) and total carbohydrates (β = 0.73, p=0.005) intake at 3 months. Carbohydrate consumption was related to decreased Bacteroides abundance over time (β = −14.9, p=0.004), after adjusting for glycosylated hemoglobin.
Seeking to better understand the factors involved prior to T1D diagnosis, we evaluated the effect of enteropathogenic parasites (Cryptosporidium spp., Cyclospora spp., G. lamblia, and Blastocystis spp.) on the bacterial structure of feces from children with autoantibodies for T1D. We detected that Cryptosporidium spp. and Cyclospora spp. affected the bacterial structure at family and genus levels, decreasing the ratio between Firmicutes and Bacteroidetes. Therefore, intestinal parasitic infection could increase the risk of T1D onset.
In conclusion, in Mexican children, the T1D associated dysbiosis is dominated by Bacteroides spp. Besides autoimmunity, diet and parasitism could have a central role in determining the T1D onset, and diet is clearly associated with dysbiosis evolution and disease control.

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