<qa>  What is the first time the participant will come to the Diabetes Center?At the first study visit Visit 1, the participant will come to the Diabetes Center after an overnight fast of at least 8 hours. 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, and an extra research tube for storage; administration of 75g Glucola load as per a standard oral glucose tolerance test OGTT protocol; and blood work for glucose and insulin at 30, 60, 90 and 120 minutes after the glucose load. This will be scheduled at a time that is convenient to the patient, with an attempt to coordinate with the patients visit to the CF clinic prior to starting lumacaftor-ivacaftor combination drug. 