Effect of Montelukast on Kidney and Vascular Function in Type 1 Diabetes

This study is testing whether a drug called montelukast (commonly used for asthma and allergies) can protect the kidneys and blood vessels in people with type 1 diabetes who already show early signs of kidney damage. **You may be eligible if...** - You are between 18 and 80 years old with type 1 diabetes for at least 5 years - You have early signs of kidney disease (protein in your urine) - Your kidney function is mildly to moderately reduced - You are already on a blood pressure medication (ACE inhibitor or ARB) at a stable dose - Your blood pressure is under 140/90 **You may NOT be eligible if...** - Your kidney function is severely reduced - You exercise vigorously more than twice a week - Your BMI is 40 or above - Your blood pressure or insulin regimen has changed recently Talk to your doctor to see if this trial is right for you.