Study design: Adult patients with type 1 diabetes will be recruited for an extensive study of sleep habits and assessment of sleep breathing disorders. When patients will present with severe sleep apnea syndrome (apnea-hypopnea index above 30 events/hour) and insufficient glycemic control (HbA1c > 7.5%), they will be randomized in continuous positive airway pressure treatment or sham-continuous positive airway pressure treatment group for three months.