The goal of this observational study is to establish a registry, screening, and individualized management platform for patients with monogenic diabetes mellitus(MDM) using internet-based and mobile application software. The main questions it aims to answer are:

• What are the genetic mutations causing MDM in China (genetic landscape)?
• How effective and safe is the individualized, molecular-diagnosis-based management platform for MDM in improving patient outcomes?

Participants will:

• Register in the MDM platform via mobile app or internet-based software
• Undergo genetic screening for MDM diagnosis
• Participate in follow-up visits for individualized management and monitoring of blood glucose control and outcomes

Inclusion Criteria:

1. Diabetes patients who developed before 25 years old; Or they were diagnosed with diabetes before the age of 35, and two or more immediate relatives were diagnosed with diabetes before the age of 45;
2. Body mass index (BMI) at diagnosis < 28 kg/m2;
3. Anti glutamic acid decarboxylase antibody (GAD Ab), anti islet cell antibody (ICA Ab), and anti insulin autoantibody (IAA Ab) were all negative;

Exclusion Criteria:

1. Secondary diabetes patients with other endocrine diseases, such as hyperthyroidism or hypothyroidism, hyperparathyroidism or hypothyroidism, acromegaly, Cushing's syndrome, autoimmune multiple endocrine diseases, etc.;
2. Systemic use of corticosteroids, immunosuppressants, and other drugs within the past 6 months;
3. Patients with malignant tumors.