The goal of this clinical trial is to observe the safety of IGT-303 in healthy volunteers and participants with Chronic Kidney Disease. The main question it aims to answer is:

Is IGT-303 safe as a single dose or multiple dose regimen when applied under the skin (subcutaneously (SC)) or to a vein (intravenously (IV)).

Researchers will compare IGT-303 against a placebo to see if IGT-303 is safe for use.

Participants will be assigned to either IGT-303 or placebo and assessed for safety and tolerability for the duration of the study.

Inclusion Criteria:

• Participant 18-75 years of age, inclusive, at Screening;
• Able to understand the key components of the study as described in the written informed consent document, and willing and able to provide written informed consent;
• Body mass index (BMI) within the range of 18.5 to 40 kg/m2 at Screening;
• Have a diagnosis of chronic kidney disease stage 2-3b, resulting from Type 2 diabetic nephropathy;
• UACR >30 mg/g, <5000 mg/g at Screening and Day -1;
• If taking antihypertensive and/or antidiabetic medication, doses of medications must be stable for at least 90 days prior to Screening;
• Participants assigned male at birth (AMAB) will be either sterile or agree to use an approved method of contraception from Screening until at least 5 half-lives plus 90 days after the last dose of study drug, or do not engage in sexual relations which carry a risk of pregnancy (does include abstinence), and agree to refrain from sperm donation and in vitro fertilization until 5 half-lives plus 90 days after the last dose of the study drug; Participants assigned female at birth (AFAB) must be of non-childbearing potential or agree to use two highly effective methods of conception from Screening until at least 5 half-lives plus 30 days after the last dose of study drug or do not engage in sexual relations which carry a risk of pregnancy (does include abstinence), and agree to refrain from egg donation and in vitro fertilization until 5 half-lives plus 30 days after the last dose of the study drug
• In the opinion of the Investigator, is able to adhere to the requirements of the study, including required overnight stays in the research site;
• For participants in Cohort 9 only, have a diagnosis of nonproliferative diabetic retinopathy

Exclusion Criteria:

• Known allergy to study medication or its components (non-medicinal ingredients) or a history of a severe allergic reaction to any drug or history of multiple food/drug allergies;
• Use of cigarettes exceeding >5 cigarettes per week at time of Screening; social/casual cigarette use (≤5 per week) is permitted during the study, but participants must be willing to abstain during inpatient confinement;
• Positive urine screen for drugs of abuse including tetrahydrocannabinol or has a positive breathalyzer test, at Screening or at Day -1;
• Any illness or medical history that would impact safety or compliance with study requirements or impact ability to interpret study data
• For participants in Cohort 9 only, presence of diabetic macular edema with anti-vascular endothelial growth factor (VEGF) treatment or vitreous hemorrhage.