Adolescents and young adults (AYA) with type 2 diabetes (T2D) have a more severe phenotype than what is seen in youth-onset type 1 diabetes or adult-onset T2D including earlier kidney and cardiovascular disease complications; and prioritizing new treatments, either for standalone use or in combination with other therapies is critical. T2D triggers the release of proinflammatory mediators called cysteinyl leukotrienes leading to damage to the kidneys and blood vessels. This clinical trial will evaluate the effects of montelukast, a cysteinyl leukotriene inhibitor, on kidney and vascular function in AYA with T2D to help direct future diabetes care to limit diabetic kidney and cardiovascular disease complications.

Inclusion Criteria:

• Age 14-24 years
• Tanner stage >2
• Diabetes onset <18 years of age and <10 years duration prior to study start
• HgbA1c <10%
• Blood pressure <130/80 mm Hg prior to randomization
• Stable anti-hypertensive regimen for at least one month prior to randomization
• BMI < 40 kg/m2
• If on SGLT2 inhibitor, ACEi/ARB or GLP-1RA, stable dose for 4 weeks
• Patient or guardian able to provide consent

Exclusion Criteria:

• T1D
• Episode of diabetic ketoacidosis or hyperosmolar hyperglycemia within 60 days
• Uncontrolled hypertension
• eGFR <30 ml/min/1.73m2
• Macroalbuminuria with urine albumin to creatinine ratio >300 mg/g
• Current participation in another research study
• Pregnancy or planning to become pregnant or currently breastfeeding
• Allergy to aspirin
• Severe hepatic impairment (Child-Pugh Class C)
• History of major psychiatric disorder
• Use of inhaled or systemic corticosteroids or long-acting beta agonists
• Iodine or shellfish allergy