This is a real-world study to explore the safety and the efficacy of washed microbiota transplantation (WMT) for patients with Type 1 Diabetes Mellitus (T1DM).

At least 20 subjects who meet all the inclusion criteria but do not meet any exclusion criteria will be enrolled in this study. Data of demographic characteristics, blood glucose fluctuation and variability, daily insulin dosage and clinical outcomes will be collected. After treatment, they will enter the follow-up period for safety and efficacy evaluation.

Inclusion Criteria:

Subjects must meet all of the following inclusion criteria to enter the study:

1. At the time of informed consent, male or non-pregnant or non-lactating female.
2. The diagnostic criteria for T1DM are confirmed by previous medical record.
3. The subject or his/her legal representative gives informed consent, fully nderstands the purpose of the study, is able to communicate effectively with the investigator, and comprehends and complies with the requirements set forth in the study.

Exclusion Criteria:

Subjects meeting any of the following exclusion criteria must be excluded from the study:

1. Diagnosed as any type of diabetes other than type 1 diabetes mellitus;
2. Subjects with severe life-threatening complications diabetes (such as ketoacidosis, or acute coronary syndrome, etc.);
3. At the time of screening, the subject or his/her legal representative refuses to take effective contraception within 3 months after the last treatment.
4. According to the judgment of the investigator, the subjects are not suitable to participate in this clinical study, or participation in this clinical study cannot guarantee the rights and interests of the subjects.

National patients with T1DM receiving WMT will be enrolled.