The sweet truth: understanding an unusually high incidence of cystic fibrosis-related diabetes in our East London paediatric cohort

Abstract

Objectives Cystic Fibrosis-Related Diabetes (CFD) affects up to 20% of children?>12 years and 50% of adults with Cystic Fibrosis (CF), and confers a sixfold increase in mortality. Despite this, its pathogenesis is not fully understood and screening is debated. We sought to understand the significantly high rate of CFD in our paediatric cohort. Methods We undertook a retrospective audit of the medical records of all children with CF managed by our centre in July 2023. We reviewed demographics, method of CFD diagnosis, CFD risk factors and modulator use. We compared those with CFD to our total CF cohort, and to the 2022 UK CF Registry Report (UKCFRR). Results Among our 83 children with CF, n = 24 had CFD (29%). Of our 10-15 year-olds with CF, 44% were on CFD treatment, more than five times higher than the UK average of 7.9%. Our CF cohort had a higher proportion of females (54% vs 47.5%) and people of Asian ethnicity (16.9% vs. 3.1%) compared to the UKCFRR. 89% had pancreatic insufficiency (PI), higher than the reported incidence of 85%. The majority (93%) of our 10-15 year-olds with CFD were diagnosed by Continuous Glucose Monitoring (CGM). In the UKCFRR, however, only 25.8% of 10-15 year-olds underwent CGM, whilst 46.9% had an Oral Glucose Tolerance Test (OGTT). In our CFD group, less childrenwere on modulator therapy compared to our total CF cohort (54% vs 67.5%). Only n = 1 (9%) of those not on modulators in our CFD group would become eligible in future, compared to 39% of those in our CF cohort. Conclusion Our high incidence of CFD may be explained by higher rates of known risk factors in our cohort (female sex, PI). The CF genotype profile of our cohort, which modulator eligibility may represent, along with ethnicity, could also contribute. The diagnostic criteria and use of CGM as a screening tool may also play a role. This study highlights the need for further research into the factors that lead to CFD, and the optimum screening method.