Toward office-based measurement of gastric emptying in symptomatic diabetics using [C-13]octanoic acid breath test

OBJECTIVE: Current methods for measuring gastric emptying by breath test re quire sampling over several hours and are too inaccurate for clinical use. The aim of this study was to develop an office-based method for measuring g astric emptying of solids in patients with diabetes using a [C-13]octanoic acid breath test. METHODS: In 22 symptomatic diabetic patients (17 insulin-dependent diabetes , 5 non-insulin-dependent diabetes) and 6 controls, we simultaneously measu red gastric emptying of an egg meal (420 kcal) by scintigraphy and [C-13]oc tanoic acid breath test. Conventional (nonlinear) methods for scintigraphic and [C-13]octanoic acid breath test emptying and generalized linear regres sion method to predict scintigraphic half-life (t(1/2)) using four breath s amples obtained during the first 3 h. RESULTS: Despite 8 h of breath sampling, the t(1/2) estimate using the conv entional method was markedly different from the scintigraphic value (Delta t(1/2): median, 113 min; range, 19-282 min). The generalized linear model ( using samples at baseline, 30, and 120 or 150 min) yielded predicted scinti graphic t(LAG) and t(1/2) that were more accurate than the conventional met hod; mean standard deviations of differences were 16 and 27 min, respective ly. Breath test correctly assessed normal or prolonged emptying in 21 of 22 patients. CONCLUSIONS: The [C-13]octanoic acid breath test can be simplified to measu re gastric t(LAG) and t(1/2) and can be expected to correctly identify norm al t(1/2) in symptomatic diabetics. Further refinement of the model will ne ed to include studies of patients with markedly delayed t(1/2). (Am J Gastr oenterol 2000;95:2751-2761. (C) 2000 by Am. Coll. of Gastroenterology).