Blood pressure drug may help preserve insulin in cystic fibrosis

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Age 14 years and older 2. Genetically-confirmed diagnosis of cystic fibrosis 3. Clinical diagnosis of pancreatic insufficiency, defined as requiring pancreatic enzyme replacement therapy (PERT) 4. Diagnosis of AGT or CFRD within 3-months of study enrollment 1. AGT is defined as having either a OGTT 2-hour glucose \>140 mg/dL and \<200 mg/dL or OGTT 1-hour glucose \>200 mg/dL 2. CFRD is defined as having a fasting glucose \>126 mg/dL and/or OGTT 2-hour glucose \>200 mg/dL 5. Willing to attempt to maximize verapamil to the goal study dosage of 360 mg PO daily 6. If taking elexacaftor/tezacaftor/ivacaftor (ETI), willing to adjust dosing Exclusion Criteria: 1. Severe lung disease indicated by forced expiratory volume in 1 second (FEV1) \<50% predicted on most recent spirometry testing 2. Body mass index (BMI) \<18 kg/m2 3. Weight \<50 kg 4. Current or planned pregnancy within the next 6 months 5. Treatment with IV antibiotics for a CF exacerbation within 1 month 6. Systemic supraphysiologic glucocorticoid use within 1 month 7. Initiation or discontinuation of a CFTR modulator within 3 months (i.e. recent change in CFTR modulator formulation/usage) 8. Current use of insulin, a GLP-1 receptor agonist, or oral anti-diabetic agent 9. Most recent HbA1c \>7% 10. Not taking a CFTR modulator due to genotype-ineligibility 11. Current use of vanzacaftor/tezacaftor/deutivcaftor 12. Known hypersensitivity to verapamil 13. Blood pressure (BP) \<90/60 (adults) or \<5th centile for age and gender (youth) in 2 out of 3 measurements 14. Heart rate (HR) \<60 bpm (adults) or \<2nd centile for age and gender (youth) in 2 out of 3 measurements 15. History of previously diagnosed vasovagal syncopal episodes related to hypotension 16. History of significant cardiac disease (e.g. severe ventricular dysfunction, hypertrophic cardiomyopathy) 17. History of certain arrhythmias (e.g. AV block, accessory pathway such as Wolff-Parkinson-White or Lown-Ganong-Levine syndromes) 18. Abnormal liver function tests defined as AST or ALT \>1.5 upper limit of normal \[ULN\] at the time of screening, or end stage cirrhosis 19. End stage renal disease on dialysis 20. History of Duchenne's muscular dystrophy 21. Need for the use of any pertinent medications (beta blockers, carbamazepine, phenobarbital, phenytoin, HMG-CoA reductase inhibitors, lithium, theophylline, clonidine). 22. Allergy to any of the components of the MMTT standardized meal