We were unable to enroll eligible subjects for the study.

The purpose of this research study is to find out if the combined therapy lumacaftor-ivacaftor affects glycemia in patient with cystic fibrosis.

This is a single center, open label study. Patients will have 1 visits at the Diabetes Research Center (DRC), or Clinical Research Center (CRC).

The participants will have been previously screened to make sure they are candidates for the study. These patients will be contacted prior to their first visit to discuss enrollment in the study.

At the study visit the participant will come to the CRC or DRC for a research visit. The following will occur at this study visit: informed consent; brief medical history; weight and height; vital signs and blood pressure; blood draw for DNA extraction, A1c and an extra research tube for storage. This will be scheduled at a time that is convenient to the patient.

Inclusion Criteria:

1. Age 18 years old or greater
2. Patients diagnosed with cystic fibrosis (CF), genotype homozygous Phe508del
3. Subject has been started on lumacaftor-ivacaftor for clinical reasons, with no contraindication for starting the drug* * Contraindications for taking drug include abnormal liver enzyme tests, renal dysfunction, pregnancy or nursing mothers

Exclusion Criteria

1. Does not have a HgbA1c within 1 year prior to starting medication.
2. Has not been on the combination therapy for at least 2 months