A review of cystic fibrosis related diabetes screening in a paediatric centre

Abstract

Background: Cystic fibrosis related diabetes (CFRD) is the most common non-pulmonary comorbidity of CF. Australian CF standards of care recommend annual screening for CFRD with 1.75 g/kg body weight (75 g) oral glucose tolerance test (OGTT) as the “gold standard” for diagnosis. Diagnosis of CFRD is made in a clinically stable patient if OGTT 2-hour plasma glucose ≥11.1 mmol/L, fasting hyperglycemia plasma glucose ≥7.0 mmol/L, and glycated hemoglobin (HbA1c) ≥6.5 mmol/L. The Queensland Children's Hospital (QCH) management of patients with CFRD procedure recommends two abnormal test results are required for a diagnosis of CFRD in the absence of symptoms. We have evaluated our screening practice at the QCH CF clinic, a large tertiary centre currently managing 450 children from birth to 18years. Methods: In 2022 189/470 (40%) children were ≥10 years of age, 24 were pancreatic sufficient and 11 had existing CFRD. 154 children were eligible for OGTT screening, only 59/154 (38%) children had screening completed through an OGTT.We explored the reasons for not meeting the standards of care for screening, including what the barriers were to OGTT, and looked at potential solutions including tests with greater feasibility within a busy clinic. Results: Key barriers included tolerability of OGTT, logistical challenges including family availability, duration of test and lack of OGTT requests. Discussion of the literature identified HbA1c as an alternate first line screening test for CFRD in children with CF. Following a Multidisciplinary Team (MDT) discussion, we introduced HbA1c screening into our annual review investigations, with a HbA1c ≥5.8% triggering referral for OGTT. Screening improved to 137/186 (73%) in the first 12 months following the introduction of annual HbA1c. OGTT's were completed for 7 children meeting the criteria of HbA1c ≥5.8%, with the 2hr glucose level normal for 4/7 and impaired for 2/7. The final child had an elevated 2hr glucose level andwent on to be diagnosed with type 1 diabetes andwas asymptomatic at this time. Conclusions: HbA1c represents a more feasible 1stline approach to screen for CFRD within a busy large tertiary paediatric clinic to identify those requiring an OGTT.