Feasibility of Outpatient Closed Loop Control With the iLet Bionic Pancreas in Cystic Fibrosis Related Diabetes

Inclusion criteria * Age \>/= 10 years and have had a diagnosis of cystic fibrosis related diabetes (CFRD) managed using either an insulin pump or multiple daily injections (MDI). * Mean continuous glucose monitoring (CGM) glucose \>/=125 mg/dl as determined by the participant's personal CGM 30-day download if CGM is used as part of their usual care. If the participant does not use CGM, hemoglobin A1c \>/= 6% within the last 6-months from available medical records will be required. * Minimum insulin requirement of \>/=0.1u/kg/day. To ensure that participants with a wide range of insulin requirements are included, participants whose insulin requirement is \<0.3u/kg/day will be limited to approximately 1/3 of the enrolled \>/=18 year old adult cohort. * Willing to wear iLet infusion sets and one Dexcom CGM sensor and change sets at least every other day in the iLet arm * Assent will be obtained for patients \<18 of age Exclusion criteria * Diabetes from etiologies other than CFRD * Unable to provide informed consent (e.g. impaired cognition or judgment) * Unable to safely comply with study procedures and reporting requirements (e.g. impairment of vision or dexterity that prevents safe operation of the bionic pancreas, impaired memory, unable to speak and read English) * Current participation in another clinical trial that, in the judgment of the principal investigator, will compromise the results of this study or the safety of the participant * Pregnancy (positive urine HCG), breast feeding, plan to become pregnant in the next 3-months, or sexually active without use of contraception o Participants must use acceptable contraception for the two weeks prior to the study, throughout the study and for the two weeks following the study. * History of hypoglycemic seizures (grand-mal) or coma in the last year * Untreated or inadequately treated mental illness (indicators would include symptoms such as psychosis, hallucinations, mania, and any psychiatric hospitalization in the last year), or treatment with anti-psychotic medications that are known to affect glucose regulation. * Unable to avoid hydroxyurea for duration of study (interferes with accuracy of Dexcom G6 CGM) * Unable to avoid taking higher than the maximum dose of acetaminophen from all sources for the duration of the study (interferes with accuracy of Dexcom G6 CGM) * Adult: 1 g every 6 hours, up to 4 g every 24 hours * Pediatric: 75 mg/kg/day in up to 5 doses, not to exceed 4000 mg/day * Have started or stopped a cystic fibrosis transmembrane conductance regulator (CFTR) modulator in the past 4 weeks. * Established history of allergy or severe reaction to adhesive or tape that must be used in the study * History of eating disorder within the last 2 years, such as anorexia, bulimia, or diabulemia or omission of insulin to manipulate weight * Use of oral (e.g. thiazolidinediones, biguanides, sulfonylureas, glitinides, DPP-4 inhibitors, SGLT-2 inhibitors) or non-insulin injectable (GLP-1 agonists, amylin) anti-diabetic medications * History of lung or liver transplant * Anticipated lung transplant (on transplant list) * No acute pulmonary exacerbation or hospitalizations within the past 4 weeks or treatment with IV antibiotics in the past 4 weeks. * Any factors that, in the opinion of the principal investigator would interfere with the safe completion of the study * History of severe liver disease, including cirrhosis or portal hypertension * Presence of a medical condition or use of a medication that, in the judgment of the investigator, could compromise the results of the study or the safety of the participant. Conditions to be considered by the investigator may include the following: * Current alcohol abuse (intake averaging \>3 drinks daily in last 30 days) or other substance abuse (use within the last 6 months of controlled substances other than marijuana without a prescription) * Unwilling or unable to refrain from drinking more than 2 drinks in an hour or more than 4 drinks in a day during the trial * Unwilling or unable or to avoid use of drugs that may dull the sensorium, reduce sensitivity to symptoms of hypoglycemia, or hinder decision making during the period of participation in the study (use of beta blockers will be allowed as long as the dose is stable and the participant does not meet the criteria for hypoglycemia unawareness while taking that stable dose, but use of benzodiazepines or narcotics, even if by prescription, may be excluded according to the judgment of the principal investigator) * Renal failure requiring dialysis * Any known history of coronary artery disease including, but not limited to, history of myocardial infarction, stress test showing ischemia, history of angina, or history of intervention such as coronary artery bypass grafting, percutaneous coronary intervention, or enzymatic lysis of a presumed coronary occlusion) * Congestive heart failure (established history of CHF, lower extremity edema, paroxysmal nocturnal dyspnea, or orthopnea) oHistory of TIA or stroke * Seizure disorder, history of any non-hypoglycemic seizure within the last two years, or ongoing treatment with anticonvulsants * History of intentional, inappropriate administration of insulin leading to severe hypoglycemia requiring treatment