The objective is to determine if lowering serum uric acid by means of allopurinol in the course of kidney disease may be effective in preventing or improving albuminuria and renal function in Type 1 Diabetic patients. The study is a double blinded, randomised, placebo-controlled cross-over clinical trial.

Inclusion Criteria:

• Albuminuria (≥30 mg/g)
• Uric Acid ≥ 0,265 mmol/l
• GFR (glomerular filtration rate) > 40 ml/min/1.73m2

Exclusion Criteria:

• History of gout or xanthinuria or other indications for uric acid lowering therapy such as cancer chemotherapy.
• Recurrent renal calculi.
• Current use of azathioprine, 6-mercaptopurine, didanosine, tamoxifen, amoxicillin/ampicillin, or other drugs interacting with allopurinol.
• Known allergy to xanthine-oxidase inhibitors.
• Renal transplant.
• Non-diabetic kidney disease.
• Home, 24h og clinical BP>180 or Diastolic BP >130 mmHg at screening.
• Cancer treatment within two years before screening.
• History of hepatitis B or C.
• History of acquired immune deficiency syndrome or human immunodeficiency virus (HIV) infection.
• History of alcohol or drug abuse.
• Breastfeeding or pregnancy or unwillingness to be on contraception throughout the trial.
• Poor mental function or any other reason to expect patient difficulty in complying with the requirements of the study.
• Serious pre-existing medical problems other than diabetes, e.g. congestive heart failure, pulmonary insufficiency.