Early Glucose Abnormalities in Cystic Fibrosis Are Preceded by Poor Weight Gain SHIHAB HAMEED, BSC (MED), MBBS1,2

OBJECTIVE — Progressive-cell loss causes catabolism in cystic fibrosis. Existing diagnostic criteria for diabetes were based on microvascular complications rather than on cystic fibrosis– specific outcomes. We aimed to relate glycemic status in cystic fibrosis to weight and lung function changes. RESEARCHDESIGNANDMETHODS — We determined peak blood glucose (BGmax) during oral glucose tolerance tests (OGTTs) with samples every 30 min for 33 consecutive children (aged 10.2–18 years). Twenty-five also agreed to undergo continuous glucose moni-toring (CGM) (Medtronic). Outcome measures were change in weight standard deviation score (wtSDS), percent forced expiratory volume in 1 s (%FEV1), and percent forced vital capacity (%FVC) in the year preceding the OGTT. RESULTS — Declining wtSDS and %FVC were associated with higher BGmax (both P 0.02) and with CGM time7.8 mmol/l (P 0.006 and P 0.02, respectively) but not with BG120 min. A decline in %FEV1 was related to CGM time7.8 mmol/l (P 0.02). Using receiver operating characteristic (ROC) analysis to determine optimal glycemic cutoffs, CGM time above 7.8 mmol/l4.5 % detected declining wtSDS with 89 % sensitivity and 86 % specificity (area unde