This study will be conducted to evaluate the efficacy and safety of GZR101-80 Injection in patients with type 2 diabetes mellitus inadequately controlled on oral antidiabetic drugs or Basal Insulin.

Inclusion Criteria:

1. Subjects sign the Informed Consent Form (ICF) before the study, fully understand the contents, process and possible adverse reactions of the study, and are able to follow the contraindications and restrictions specified in this protocol.
2. At the age of 18-75 (inclusive) at the time of informed consent, male or female.
3. Body mass index (BMI) ≥18.5 and ≤35.0 kg/m2 at screening.
4. According to the diagnostic criteria and classification of diabetes mellitus issued by the World Health Organization (WHO) in 1999, and the supplementary diagnostic criteria recommended by WHO for diagnosis with Hemoglobin A1c (HbA1c) (2011), the time to diagnose T2DM is ≥ 180 days at screening.

Exclusion Criteria:

1. Confirmed or suspected type 1 diabetes mellitus or specific types of diabetes due to other causes (monogenic diabetes, cystic fibrosis, pancreatitis, drug- or chemical-induced diabetes, etc.) prior to screening.
2. Grade 3 hypoglycemia within 3 months before screening.
3. Subjects who have any diseases that may affect HbA1c testing at screening, or subjects who have donated blood, lost more than 400 mL of blood, or received blood transfusion within 3 months prior to screening.
4. Diagnosis of active malignant tumor within 5 years prior to screening (excluding adequately treated or resected non-metastatic basal or squamous cell skin cancer, in situ cancer of cervix, or prostate cancer in situ), or with a high suspicion of potential malignant tumor at screening.