The aim of CF Research News is to bridge the gap between people with cystic fibrosis (CF) and the researchers investigating CF, providing access to patients, parents, relatives, friends and caregivers to all scientific work published in the Journal of Cystic Fibrosis (JCF). The following article was published in August 2018
What was your research question?
Do blood sugars in patients with cystic fibrosis, measured by continuous glucose monitoring, improve after starting lumacaftor/ivacaftor?
Why is this important?
Previously, a small study found improvements in insulin secretion and diabetes for patients with CF and G551D mutations after starting ivacaftor treatment. The effects of lumacaftor/ivacaftor (Orkambi®) on blood sugars in patients with F508del mutations are unknown. As newer CFTR modulators are developed for different mutations, it is important to perform ongoing assessments of the effects of these medications on blood sugars and CF-related diabetes.
What did you do?
Nine individuals, ages 11-15 years, with homozygous F508del mutations, wore a continuous glucose monitor (CGM) before and after Orkambi® treatment. One had CF-related diabetes, 5 had abnormal glucose tolerance tests, and 3 had normal glucose tolerance tests prior to Orkambi®. CGM data was collected and compared roughly a median of 26 weeks before and 29 weeks after Orkambi® initiation.
What did you find?
There were no significant differences in blood sugars measured by continuous glucose monitoring before vs after Orkambi® treatment in this small group of people. In fact, one individual with normal glucose tolerance before Orkambi® developed diabetes after Orkambi® start.
What does this mean and reasons for caution?
Blood sugar abnormalities in the F508del population may be harder to correct with Orkambi® than in the G551D population treated with ivacaftor. However, in this study, insulin secretion problems, which are the underlying cause of blood sugar abnormalities in diabetes, were not directly measured.
What’s next?
Future studies measuring both insulin secretion and blood sugar changes, before and after the start of newer CFTR modulator drugs, are needed to better understand the impacts of these medications on blood sugars, risk for diabetes, and diabetes progression.
Authors: Angel Li, Tim Vigers, Laura Pyle, Edith Zemanick, Kristen Nadeau, Scott D. Sagel, Christine L. Chan
Original manuscript citation in PubMed: www.ncbi.nlm.nih.gov/pubmed