[C-13]OCTANOIC ACID BREATH TEST FOR NONINVASIVE ASSESSMENT OF GASTRIC-EMPTYING IN DIABETIC-PATIENTS - VALIDATION AND RELATIONSHIP TO GASTRIC SYMPTOMS AND CARDIOVASCULAR AUTONOMIC FUNCTION

Since there is a need for a widely applicable non-invasive test to ass ess gastric emptying in diabetic patients, we evaluated the sensitivit y, specificity, and reproducibility of the [C-13]octanoic acid breath test as compared with scintigraphy. Moreover, we examined the relation ship between the breath test indices and gastric symptoms, cardiovascu lar autonomic function, and metabolic parameters. Forty healthy contro l subjects and 34 diabetic patients were studied. Three indices of gas tric emptying, assessed by the breath test, were computed: half-emptyi ng time (t(1/2breath)), gastric emptying coefficient (GEC), and lag ph ase. Furthermore, the half-emptying time, measured by scintigraphy (t( 1/2scint)), was calculated and gastric symptoms and cardiovascular aut onomic neuropathy (CAN) were scored. The coefficients of variation of day-to-day reproducibility in 10 healthy subjects were 29.6% for t(1/2 breath), 7.4% for GEC, and 46.5% for lag phase. An abnormal delay for t(1/2scint) (>100 min) or t(1/2breath) (> 200 min) was noted in 12 pat ients. Based on the results for t(1/2scint), the sensitivity of t(1/2b reath) and GEC was 75% and the specificity was 86%. Both t(1/2breath) (r(s) = 0.523; p < 0.05) and GEC (r(2) = -0.594; p < 0.05) were signif icantly associated with the gastric symptom score. A significant relat ionship to the CAN score was demonstrated for t(1/2breath) (r(s) = 0.4 48; p < 0.05), GEC (r(s) = -0.467; p < 0.05), and t(1/2scint), (r(s) = 0.602; p < 0.05). There were no significant associations of the breat h test indices with the blood glucose levels during the test, HbA(1c), age, and duration of diabetes. In patients with abnormal t(1/2scint) (n = 12) not only was t(1/2breath) significantly prolonged and GEC red uced, but also the scores of CAN and gastric symptoms were significant ly increased as compared with those who had a normal t(1/2scint) (n = 22). We conclude that the [C-13]octanoic acid breath test represents a suitable measure of delayed gastric emptying in diabetic patients whi ch is associated with the severity of gastric symptoms and CAN but not affected by the blood glucose level.