Is oral therapy with Repaglinide equivalent to insulin therapy with three daily injections with respect to blood glucose control, weight and pulmonary function over 2 years in patients with cystic fibrosis and secondary diabetes mellitus? That is the question examined in the phase III trial.

Diabetes mellitus may be present in patients with cystic fibrosis (mucoviscidosis) starting in the second decade of life. The prevalence increases rapidly with increasing age. As life-expectancy increases in CF, CF-related diabetes will be diagnosed more frequently in the future. Negative consequences of secondary diabetes in cystic fibrosis include:

• Catabolic metabolism
• Weight loss
• More frequent / more severe infections
• Deterioration of pulmonary function
• Reduced life-expectancy
• Diabetic micro vascular complications (retinopathy, nephropathy, neuropathy)

Up to date, no data are available to answer the question, whether secondary diabetes in CF should always be treated by insulin therapy. Several centres report the successful management of CF-related diabetes using oral anti-diabetic drugs at least for some years. Oral therapies would be less invasive for a patient group which is highly traumatised by a very demanding therapy (multiple drugs including antibiotics, pancreas enzymes, bronchodilators, mucolysis, in addition to physiotherapy, regular inpatient iv-antibiotic therapy etc, finally lung transplants in a subgroup of patients).

Inclusion Criteria:

Inclusion Criteria for the Screening:

• Diagnosed cystic fibrosis
• Age 10 years and older

Inclusion Criteria for the therapeutic part of the study:

• Newly diagnosed Diabetes mellitus in the screening

Exclusion Criteria:

Exclusion Criteria for Screening:

• Diabetic keto-acidosis (blood glucose > 350 mg/dl and arterial pH < 7.25)
• Already treated Diabetes mellitus by oral antidiabetic medication or insulin

Exclusion Criteria for the therapeutic part of the study:

• Systemic steroid therapy during the last 3 months
• Transplantation (status post TX or on the waiting list for TX)
• Beginning pulmonary insufficiency, FEV1 < 35% at pulmonary function test in stable condition
• Pregnancy
• Already diagnosed and treated diabetes mellitus
• Patients with diabetic keto-acidosis (blood glucose > 350 mg/dl and arterial pH < 7.25) with or without diabetic coma
• Severe liver insufficiency (chronic hepatitis B, AST or ALT twice the upper limit of normal, Quick's value < 70% which is a contraindication to use Repaglinide)
• Treatment with an indispensable important drug which contraindicates Repaglinide
• PEG/ gastric tube/ total parenteral alimentation for more than 4 weeks during the study
• CF-patients with type 1 diabetes
• Not patient's consent to randomisation and therapeutic trial
• Participation on other medical trial