Inclusion Criteria:
* Adults (≥18 years) with type 1 diabetes
* Diabetes duration of ≥5 years
* Persistent urine albumin-to-creatinine ratio (UACR) ≥ 30 mg/g, on the most recent two measurements within the prior 3 years
* Estimated glomerular filtration rate ≥ 30 mL/min/1.73m2
* Stable doses of drugs altering blood pressure (e.g., Angiotensin-converting enzyme inhibitor) required for at least 4 weeks prior to randomization, and requested for the duration of the trial
* Stable doses of lipid-lowering medications required for at least 4 weeks prior to randomization, and requested for the duration of the trial
* Adequate contraceptive method for females of child-bearing potential
Exclusion Criteria:
* HbA1c \>9%, recent diabetic ketoacidosis, hyperosmolar hyperglycemic state or severe illness requiring hospitalization in past 30 days
* Other causes of diabetes mellitus, including type 2 diabetes and maturity-onset diabetes of the young (MODY)
* Chronic kidney disease unrelated to diabetes
* Personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) or thyroid nodule palpated by endocrinologist at screening
* Personal history of pancreatitis
* Current/planned pregnancy or nursing
* Uncontrolled thyroid disease or hypertension (Systolic blood pressure \[SBP\] ≥ 160 mm Hg or diastolic blood pressure \[DBP\] ≥ 100 mm Hg despite treatment)
* Proliferative retinopathy with treatment in the past 6 months
* Uncontrolled or potentially unstable diabetic retinopathy or maculopathy, verified by fundus examination with pupil dilation unless performed using a digital fundus photography camera specified for non-dilated examination
* More than 2 severe hypoglycemic episodes (requiring glucagon and/or assistance from another person) in the past 6 months
* Frequent hypoglycemia during the last two weeks of the study run-in phase (time below range \[\<70 mg/dL\] ≥4%)
* Pramlintide and the use of glycemia treatments not approved for type 1 diabetes by the FDA, e.g., metformin, SGT-2 inhibitor, GLP-1 receptor agonist, closed loop insulin delivery using unapproved algorithms
* Significant systemic conditions or treatment such as cancer or immunomodulators
* Known liver disease other than non-alcoholic fatty liver disease (NAFLD) or aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \>100 IU/L, history of severe gastrointestinal disease (e.g., gastroparesis) or gallstones
* Body mass index \<20 kg/m2
* Inability to cooperate with or clinical contraindication for magnetic resonance imaging including severe claustrophobia, nonremovable devices, implanted metal
* Known or suspected allergy/sensitivity to semaglutide or its excipients
* Pregnant, breast feeding, or the intention of becoming pregnant
* The receipt of any investigational drug within 3 months prior to this trial
* Previously randomized in this trial
