This study aims to establish a system for identifying and screening high-risk individuals for type 1 diabetes (T1D) and a standardized management pathway for high-risk individuals. It is a prospective cohort study. We plan to enroll 340 eligible subjects, including 40 healthy controls of the same gender and age, 150 T1D patients, and 150 first-degree relatives of T1D patients. The follow-up visit cycle for T1D patients and their first-degree relatives is 4 years. Blood samples will be collected annually for genetic polymorphism testing, pancreatic islet-related autoantibody measurement, blood glucose, hemoglobin A1c, and pancreatic function assessment. Urine samples will be collected for urine proteomics measurement. Fecal samples will be collected for fecal intestinal microbiota measurement. The value of pancreatic islet autoantibody markers in predicting T1D high-risk individuals will be evaluated, and a multi-gene risk score (PRS) prediction model will be established for subtypes of T1D, including acute and chronic T1D. A comprehensive T1D high-risk individual identification and screening system will be established and promoted for application.

1. For patients with type 1 diabetes, the intervention includes two aspects: Firstly, at the time of subject enrollment, a 12-hour structured course is conducted, covering various aspects such as diabetes diet, exercise, blood sugar monitoring, insulin injection, complication prevention, and psychological adjustment. Secondly, regular outpatient follow-ups are carried out, with a frequency of once every 3 months. The follow-up content includes routine outpatient visit-related items, such as blood sugar, islet function, liver and kidney function, blood lipid, etc., as well as screening for diabetes complications. Follow-ups are conducted regularly based on the time of type 1 diabetes diagnosis.
2. For the first-degree relatives of patients with type 1 diabetes: At the time of subject enrollment, blood samples are taken for genetic polymorphism testing, islet-related autoantibody determination, blood sugar, glycosylated hemoglobin, and islet function assessment; urine samples are collected for urine proteomics determination. Stool samples are collected for stool intestinal flora determination. Subsequently, follow-ups are conducted once a year, with blood sampling and collection of urine and stool samples for the same items as in the baseline follow-up.
3. For healthy control populations, no follow-up arrangements are made. At the time of subject enrollment, blood samples are taken for genetic polymorphism testing, islet-related autoantibody determination, blood sugar, glycosylated hemoglobin, and islet function assessment; urine samples are collected for urine proteomics determination. Stool samples are collected for stool intestinal flora determination.

1. Inclusion and exclusion criteria for patients with type 1 diabetes:

   Inclusion criteria:

   • Meet the WHO's diabetes diagnostic criteria, diagnosed as type 1 diabetes; ② Able and willing to participate in 12 hours of structured education training;

     • Able and willing to undergo regular outpatient follow-up;

       • Volunteer to participate in the study and sign informed consent.

   Exclusion criteria:

   ① Non-type 1 diabetic patients;

   • Severe microvascular complications: proliferative retinopathy; Urinary albumin/urinary creatinine > 300mg/g, or 24-hour urinary protein quantity > 1g/d; Uncontrolled painful diabetic neuropathy and significant diabetic autonomic neuropathy; ③ Patients who had acute cerebrovascular accident, acute coronary syndrome, peripheral artery disease requiring hospitalization or underwent vascular intervention or amputation within 3 months before enrollment; Blood pressure is consistently higher than 180/110mmHg and cannot be controlled within 160/110mmHg within 1 week; Serum creatinine clearance was less than 30ml/min/1.73m2(calculated according to CKDEPI formula), alanine aminotransferase ≥3 times the upper limit of normal, total bilirubin ≥2 times the upper limit of normal for more than 1 week;

(6) Have used drugs that may affect blood sugar for more than 1 week within 12 weeks, such as oral/intravenous glucocorticoids, growth hormones, estrogen/progesterone, high-dose diuretics, antipsychotic drugs, etc.; However, small doses of diuretics (hydrochlorothiazide < 25mg/d, indapamide ≤1.5mg/d) for antihypertensive purposes, and physiological dosages of thyroid hormones used for replacement therapy are not subject to this limit; (7) Systemic infection or serious concomitant disease; Patients with malignant tumors or chronic diarrhea; Other circumstances that cause the subjects to be unable to complete the study: such as serious cognitive dysfunction, mental illness, etc.;

⑨ The subject is uncooperative, unable to follow up, or the investigator judges that it may be difficult to complete the investigator;

⑩ Other conditions deemed unsuitable for inclusion by the investigator. The study physician will determine whether you are suitable for the study based on your actual condition and the inclusion and exclusion criteria in the study protocol.

(2) Inclusion and exclusion criteria for first-degree relatives of patients with type 1 diabetes:

Inclusion criteria:

• First-degree relatives of patients with type 1 diabetes (including parents, children, siblings);

  • Age ≥4 years old; ③ Able and willing to undergo regular outpatient follow-up; ④ Volunteer to participate in the study and sign informed consent.

Exclusion criteria:

• Type 1 diabetes has been diagnosed;

  • Second degree relatives of patients with type 1 diabetes; ③ Patients who could not complete regular outpatient follow-up. (3) Inclusion and exclusion criteria for healthy people:

Inclusion criteria:

• Age ≥40 years old;

  • No history of diabetes; ③ Fasting blood glucose < 6.1mmol/L, 2-hour glucose load blood glucose < 7.8mmol /L, glycosylated hemoglobin < 5.7%; ④ Volunteer to participate in the study and sign informed consent.

Exclusion criteria:

①A definite diagnosis of type 1 diabetes in a first - or second-degree relative.

It is planned to recruit 340 subjects meeting the inclusion criteria, including 40 healthy controls matching gender and age, 150 patients with T1D, and 150 first-degree relatives of T1D patients.