Trahair, L.G.Nauck, M.A.Wu, T.Stevens, J.E.Buttfield, M.D.Hatzinikolas, S.Pham, H.Meier, J.J.Rayner, C.K.Horowitz, M.L.Jones, K.2025-07-222025-07-222022Internal Medicine Journal, 2022; 52(S2):54-551444-09031445-5994https://hdl.handle.net/2440/146218Background: Breath tests utilising 13C-labelled substrates have been applied widely for the assessment of gastric emptying. A limitation of conventional breath test modelling is that the results should be regarded as notional, rather than precise. Wagner- Nelson analysis is a pharmacokinetic model that can be utilised to generate a gastric emptying curve from the % ¹³CO₂ measured in breath samples. Aims: To compare Wagner-Nelson analysis with (i) scintigraphy and (ii) conventional breath test modelling to quantify gastric emptying in type 2 diabetes. Methods: Thirteen subjects with type 2 diabetes (age 68.1±1.5 years, body mass index 31.0±0.9kg/m², glycated haemoglobin (HbA1c) 6.3±0.2%) consumed a mashed potato meal comprising 65g powdered potato, 20g glucose, 250ml water, an egg yolk labelled with 100μL 13Coctanoic acid and 20MBq 99mTc-calcium phytate. Scintigraphic data were acquired and breath samples collected for 4 hours after the meal. Gastric emptying curves were derived based on each technique; the 50% emptying time and intragastric retention at 60min were also calculated. Results: With Wagner-Nelson analysis, a Kel=0.60 (the elimination constant) best approximated the scintigraphic gastric emptying curve. There was a relationship between the T50 calculated with scintigraphy and that by both Wagner-Nelson Kel=0.60 (r²=0.45, P<0.05) and conventional analysis (r²=0.44, P<0.05). There was no significant difference in the 50% gastric emptying time measured by scintigraphy (68.5±4.8 min) and Wagner-Nelson Kel=0.60 (71.3±4.5 min), however, the gastric emptying time calculated by conventional analysis was much greater at 164.7±6.0 min (P<0.001). Conclusion: In type 2 diabetes, gastric emptying of a mashed potato meal measured using a ¹³C-octanoic acid breath test analysed with Wagner-Nelson Kel=0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not.en© 2022 Royal Australasian College of Physicians. Copyright of individual abstracts remains with the authors.General & Internal Medicine; Life Sciences & Biomedicine; Medicine, General & Internal; Science & TechnologyJournal article10.1111/imj.157632024-05-06641148Wu, T. [0000-0003-1656-9210]Pham, H. [0000-0002-7055-3108]Rayner, C.K. [0000-0002-5527-256X]Horowitz, M.L. [0000-0002-0942-0306]Jones, K. [0000-0002-1155-5816]