Background In cystic fibrosis, highly variable glucose tolerance is suspected.
However, no study provided within-patient coefficients of variation. The main
objective of this short report was to evaluate within-patient variability of
oral glucose tolerance. Methods In total, 4,643 standardized oral glucose
tolerance tests of 1,128 cystic fibrosis patients (median age at first test:
15.5 [11.5; 21.5] years, 48.8% females) were studied. Patients included were
clinically stable, non-pregnant, and had at least two oral glucose tolerance
tests, with no prior lung transplantation or systemic steroid therapy.
Transition frequency from any one test to the subsequent test was analyzed and
within-patient coefficients of variation were calculated for fasting and two
hour blood glucose values. All statistical analysis was implemented with SAS
9.4. Results A diabetic glucose tolerance was confirmed in 41.2% by the
subsequent test. A regression to normal glucose tolerance at the subsequent
test was observed in 21.7% and to impaired fasting glucose, impaired glucose
tolerance or both in 15.2%, 12.0% or 9.9%. The average within-patient
coefficient of variation for fasting blood glucose was 11.1% and for two hour
blood glucose 25.3%. Conclusion In the cystic fibrosis patients studied, a
highly variable glucose tolerance was observed. Compared to the general
population, variability of two hour blood glucose was 1.5 to 1.8-fold higher
