Evaluation of glucose tolerance in cystic fibrosis: comparison of 50-g and 75-g tests.
BACKGROUND
The recommended tests for evaluation of glucose tolerance in cystic fibrosis are the fasting blood glucose (FBG) and the 75-g, fasting, 2-h oral glucose tolerance test (OGTT). We compared a 50 g, non-fasting, 1-h glucose challenge test (GCT) to the standard OGTT.


METHODS
During their regularly scheduled visit to the cystic fibrosis clinic, patients underwent a 50-g, non-fasting 1-h GCT and were asked to complete a standard 75-g, fasting, 2-h OGTT within one week of their clinic visit.


RESULTS
Fifty-seven patients underwent glucose tolerance testing. Of these, 31/57 (54%) completed both tests. Hyperglycemia was detected on both tests in 9/31 (29%) patients, 11/31 (35%) tested positive only on the GCT, while all those with positive OGTTs had positive GCTs (p<0.01).


CONCLUSIONS
In this study, the GCT identified all patients who meet the criteria for abnormal glucose tolerance on an OGTT. There was a large subgroup that was positive for glucose intolerance only on the GCT. These individuals represent a distinct biochemical subgroup of uncertain significance that warrants closer evaluation. Although the GCT can be completed in a non-fasting state and in conjunction with regular blood work or clinic visits, the anticipated greater compliance was not seen.
Lee
Kathleen M N
KM
Cystic Fibrosis Clinic, St. Paul's Hospital 8B providence, 1081 Burrard Street, Vancouver, BC, Canada.
Miller
Robert J H
RJ
Rosenberg
Frances M
FM
Kreisman
Stuart H
SH
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000097:blood* / Q000150:complications; D003920:Diabetes Mellitus / Q000097:blood* / Q000209:etiology; D005215:Fasting / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000209:etiology; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D001786:Blood Glucose