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J Diabetes Complications. 2019 Sep 11:107449. doi: 10.1016/j.jdiacomp.2019.107449. [Epub ahead of print]

Bacteroidetes and Firmicutes levels in gut microbiota and effects of hosts TLR2/TLR4 gene expression levels in adult type 1 diabetes patients in Istanbul, Turkey.

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Department of Medical Microbiology, Beykent University, School of Medicine, Istanbul, Turkey.
Department of Medical Microbiology, Cerrahpasa School of Medicine, Istanbul University-Cerrahpaşa, Istanbul, Turkey. Electronic address:
Department of Medical Microbiology, Cerrahpasa School of Medicine, Istanbul University-Cerrahpaşa, Istanbul, Turkey.
Department of Endocrinology, Gaziosmanpasa Taksim Training and Research Hospital, Health Sciences University, Istanbul, Turkey.
Vocational School of Health Service, Department of Medical Services and Technics, Istanbul University - Cerrahpasa, Istanbul, Turkey.
Department of Endocrinology, Gaziosmanpasa Hospital, Yeni Yuzyil University, Medical Faculty, Istanbul, Turkey.
Department of Medical Microbiology, School of Medicine, Namık Kemal University, Tekirdağ, Turkey.



The aim of this study was to determine and compare the levels of both Bacteroidetes and Firmicutes in the gut microbiota and TLR2/TLR4 gene expression in the blood of patients with type 1 diabetes mellitus (T1DM) and healthy individuals. These results may serve as a preliminary assessment to guide future research.


Between January and October 2014, stool and blood samples were collected from 53 adult T1DM patients and 53 age- and gender-matched healthy individuals. Bacteroidetes and Firmicutes levels were assessed from stool sample DNA and TLR2 and TLR4 expression levels were analyzed via qPCR using RNA from EDTA blood samples from both patients and healthy controls.


The amounts of Bacteroidetes and Firmicutes were statistically significantly higher and lower, respectively, in the T1DM group than in the healthy control group (p < 0.001 and p < 0.001, respectively). In addition, the Firmicutes/Bacteroidetes ratios in patients with T1DM were significantly lower than in healthy controls. The TLR4 and TLR2 gene expression levels in T1DM patients were significantly upregulated and downregulated, respectively, compared to those in the control group.


Our data are the first to show a relationship between T1DM and gut microbiota in our country. In addition, our results provide information about the connections between T1DM, gut microbiota, and TLR2 and TLR4 expression. We believe that Bacteroidetes and Firmicutes in the gut microbiota may play a role in the autoimmune process of T1DM and that these findings should be further investigated in the future.


Bacteroidetes; Firmicutes; Gut microbiota; Toll-like receptors; Type 1 diabetes

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