This study is a multicenter cross-sectional research project, planning to enroll 1000 patients with Type 1 Diabetes Mellitus (T1DM). By reviewing clinical data, physical examinations, questionnaires, continuous glucose monitoring, and subcutaneous fat ultrasound, we aim to understand the current status of treatment and metabolism in Chinese T1DM patients and analyze the potential factors that may affect their blood sugar control and metabolic indicators. A cost-effectiveness analysis will be conducted on Chinese T1DM patients using continuous glucose monitoring systems to identify the groups that benefit most from these systems.

This study is a multicenter cross-sectional research project, planning to enroll 1000 patients with Type 1 Diabetes Mellitus (T1DM). This study will collect multicenter data on T1DM patients, including sociodemographic information, anthropometric measurements, glycemic indices (glycated hemoglobin, fasting blood glucose, postprandial blood glucose), acute and chronic complications, other important metabolic indicators (blood lipids, vitamin D), insulin treatment methods, blood glucose monitoring status, diabetes education, diet and exercise, social and psychological support, and extra-pancreatic autoimmune diseases. The aims are: 1. To understand the current state of treatment and glycemic metabolism in Chinese T1DM patients and to analyze the potential factors that may affect their glycemic indices. 2. To understand the current status of continuous glucose monitoring (CGM) usage in Chinese T1DM patients and to analyze the impact of CGM on blood glucose control, acute and chronic complications, and quality of life in T1DM patients. 3. Through cost-benefit analysis, to identify potential beneficiary groups for CGM, providing objective evidence for the demand of this technology to healthcare professionals and diabetes patients; to provide effective information for the formulation of medical insurance reimbursement policies for continuous glucose monitoring.

Inclusion Criteria:

• Volunteer to participate and be able to sign informed consent
• Patients with type 1 diabetes
• At least one of the following three clinical characteristics must be met: The disease presents initially with diabetic ketoacidosis (DKA) or ketonuria; The presence of islet-related autoantibodies, such as islet cell antibodies, tyrosine phosphatase antibodies, or glutamic acid decarboxylase (GAD) antibodies, is detected positively; Both fasting and postprandial C-peptide levels are ≤0.6 ng/mL.

Exclusion Criteria:

• Other types of diabetes.
• Patients who cannot cooperate with the use of continuous glucose monitoring, clinical data collection, and questionnaire completion.

The study aims to recruit 1,000 patients with Type 1 Diabetes Mellitus (T1DM) from endocrinology departments across various centers between June 2024 and June 2025, both inpatient and outpatient.