The primary objective is to assess the impact of three months of treatment with an active vitamin D analogue on a risk marker for excess overall mortality and cardiovascular morbidity/mortality in Type 1 diabetic patients with diabetic kidney disease. The hypothesis is that active vitamin D analogue treatment reduces the risk of cardiovascular morbidity and mortality in patients with type 1 diabetic kidney disease.

Inclusion Criteria:

• 18-75 years of age
• Type 1 diabetes mellitus
• Diabetic nephropathy (defined by persistent albuminuria, > 300 mg/24 hr or 200µg/min in 2 of 3 consecutive samples, presence of diabetic retinopathy and absence of clinical or laboratory evidence of other kidney or renal tract disease
• Chronic kidney disease stage 3 and 4
• S-Parathyroid hormone (s-PTH)> 35pg/ml
• Stabile RAAS-blocking and diuretic treatment

Exclusion Criteria:

• Other kidney disease than diabetic nephropathy
• Myocardial infarction within the last three months prior to visit 1
• Coronary artery revascularization within the last three months prior to visit 1
• Transitional cerebral ischemia (TCI) or apoplexia within the last three months prior to visit 1
• Cardiac Failure (NYHA Class III or IV)
• Kidney Failure (GFR <15ml/min), dialysis, kidney transplantation)
• Liver disease with serum alanine aminotransferase (ALT>3 x the normal value
• Alcohol/drug abuse
• Hypercalcemia (serum ionized calcium >1.35 mmol /L)
• Medication with phosphate and/or vitamin D-containing medications, which can not be paused during the study
• Clinical signs of vitamin D toxicity
• Pregnant or nursing women
• Fertile women not using chemical or mechanical (IUD) contraceptive methods
• Current disulfiram treatment
• Allergy to the study drug
• Patient unable to understand the informed consent
• Any other condition or therapy which, in the opinion of the investigator, makes the patient not suited for participation.