Glycemic Characterization and Pancreatic Imaging Correlates in Cystic Fibrosis
Condition: Cystic Fibrosis; Cystic Fibrosis-related Diabetes; Cystic Fibrosis Liver Disease; Pancreatic Steatosis; Hepatic Steatosis
MeSH terms: Cystic Fibrosis; Liver Diseases; Fatty Liver; Fibrosis
Study type: Observational

Summary: 
      The purpose of this study is to investigate the utility of a continuous glucose monitor
      device (CGM) in screening for cystic fibrosis related diabetes. The investigators will also
      study how fat deposition in the pancreas and liver impacts insulin production and response,
      as measured by a frequently sampled oral glucose tolerance test.
    

Detailed description: 
      Cystic Fibrosis Related Diabetes (CFRD) occurs in 20% of adolescents and 30-40% of adults
      with cystic fibrosis. CFRD is associated with reduced lung function, lower body mass index,
      and increased mortality. The CF Foundation recommends yearly Oral Glucose Tolerance Test
      (OGTT) for all CF patients beginning at age 10 years. Unfortunately adherence to screening
      recommendations is poor, with fewer than 50% of the eligible CF patients completing OGTT each
      year. Additionally, the OGTT has been criticized for poor reproducibility and for not
      accurately reflecting real-life glycemic excursions.

      The FreeStyle Libre Pro is a blinded CGM that can record up to 14 days of home-living glucose
      data on one sensor. This quarter-sized device is placed on the upper arm and requires no
      fingerstick calibrations. Multiple studies have demonstrated the utility of CGM in CF
      patients, but no study has determined the utility of CGM in replicating the results of an
      OGTT. The use of CGM in CFRD screening has the potential to reduce screening burden, increase
      screening adherence and provide useful information about home glycemic excursions.

      Pancreatic steatosis is common in CF with complete pancreatic fat replacement occurring in
      some cases. Pancreatic steatosis is also seen in patients with type 2 diabetes and may impact
      insulin secretion or the rate of beta cell decline. MRI is the most sensitive tool for
      detecting pancreatic steatosis. Ferrozzi described four patterns of pancreatic fat
      replacement in CF patients: (1) diffusely hyperintense with variable lobular pattern, (2)
      homogenous hyperintensity without lobular pattern, (3) hyperintense parenchyma with focal
      hypointensity, and (4) no structural or signal intensity changes. No studies have directly
      compared the degree of pancreatic steatosis with OGTT derived measures of insulin secretion
      or glycemic excursions on CGM.

      Hepatic steatosis is also common in CF patients and has an unclear impact on insulin
      sensitivity. Outside of CF, hepatic steatosis is associated with insulin resistance.

      This study has two aims:

      Aim 1: Determine how closely the FreeStyle Libre Pro CGM can replicate the results of an
      in-clinic oral glucose tolerance test.

      Aim 2: Explore whether pancreatic and hepatic steatosis correlated with insulin secretion and
      sensitivity in CF patients.
    

Intervention name(s): Frequently Sampled Oral Glucose Tolerance Test and CGM; MRI Pancreas and Liver
Intervention type(s): Device; Radiation
Intervention description(s): Patients will undergo a 2 hour frequently sampled oral glucose tolerance test while wearing an active FreeStyle Libre Pro sensor. Using as a tool to collect data.; Patients will undergo an MRI of the pancreas and liver
Intervention MeSH terms: Pancrelipase
Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients with cystic fibrosis will be recruited from the LeRoy W. Matthews CF Center at UH
        Cleveland Medical Center.
      
Keywords: continuous glucose monitor; cystic fibrosis; cystic fibrosis related diabetes