Peak OGTT glucose is associated with lower lung function in young children with cystic fibrosis.

BACKGROUND: Screening for Cystic Fibrosis-related diabetes is recommended in patients with CF <10 years old when there are concerns about growth and lung function. The Oral Glucose Tolerance Test (OGTT) is recommended but has not been validated in this cohort. We sought to determine whether the 2-h OGTT, the gold standard diagnostic test for CFRD, detects clinical decline in children with CF <10 years old. METHODS: We analysed blood glucose(BG) levels collected every 30 min during OGTT in 27 children with CF < 10 years old, comparing the 2-hour BG (BG120min), peak BG (BGmax) and Area Under the Curve(AUC) for glucose and the association with lung function and nutritional status. We also compared the OGTT results with results from Continuous Glucose Monitoring (CGM) performed in 11 participants. RESULTS: The BGmax was higher than the BG120min in 25/27 (93%) participants. There was a significant inverse correlation between BGmax and weight z-score (rs = -0.56, p = .002) and between BGmax and FEV1 (rs = -0.54, p = .014) that was not present for BG120min. A significant inverse correlation was also identified between fasting insulin level and elevated glucose on CGM, defined as AUC >7.8 mmol/L (rs = - 0.69, p = .027) or as % time > 7.8 (rs = - 0.76, p = .011). CONCLUSIONS: Children with CF < 10 years of age with higher BGmax on OGTT have lower lung function and weight z- scores that may not be identified using the 2 h OGTT BG120min. CGM also identifies glucose excursions in young children with CF.