Objective: To define phenotypes of gastric myoelectrical abnormalities and relation to symptoms in people with longstanding T1D, compared to matched healthy controls, using a novel non-invasive body surface gastric mapping (BSGM) device. Research design and methods: BSGM was performed on people with T1D of >10 years duration and matched controls, employing Gastric Alimetry (Alimetry, New Zealand), comprising a high-resolution 64-channel array, validated symptom logging App, and wearable reader. Results: 32 people with T1D were recruited (15 with a high symptom burden), and 32 controls. Those with symptoms showed more unstable gastric myoelectrical activity, (Gastric Alimetry Rhythm Index 0.39 vs 0.51, p=0.017; and lower average spatial covariance 0.48 vs 0.51, p=0.009) compared with controls. Those with T1D and symptoms also had higher prevalence of peripheral neuropathy (67% vs 6%, p=0.001), anxiety/depression diagnoses (27% vs 0%, p=0.001), and mean HbA1c levels (76 vs 56 mmol/mol, p<0.001). BSGM defined distinct phenotypes in participants including those with markedly unstable gastric rhythms (4/32, 12.5%), and abnormally high gastric frequencies (10/32, 31%). Deviation in gastric frequency was positively correlated with symptoms of bloating, upper gut pain, nausea and vomiting, and fullness and early satiation (r>0.35, p<0.05) Conclusion: Gastroduodenal symptoms in people with longstanding T1D correlate with gastric myoelectrical abnormalities on BSGM evaluation, in addition to glycemic control, psychological comorbidities, and peripheral neuropathy. BSGM using the Gastric Alimetry device identified a range of myoelectrical phenotypes, representing both myogenic and neurogenic mechanisms, which represent targets for diagnosis, monitoring and therapy.

Professor Greg O'Grady, holds grants and intellectual property in the field of gastrointestinal electrophysiology and is a co-founder and Director in University spin-out companies: The Insides Company Ltd and Alimetry Ltd. Dr Gharibans holds grants and intellectual property in the field of gastrointestinal electrophysiology and is a co-founder and Director of Alimetry Ltd. Dr Calder, Dr Schamberg, Dr Waite, Dr Daker, and Prof. Andrews are members of Alimetry Ltd. The remaining authors have no conflicts of interest to declare.

This project was supported by the Health Research Council of New Zealand, the NIH (R56 DK126935) and the John Mitchell Crouch Fellowship from the Royal Australasian College of Surgeons.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Auckland Health Research Ethical Committee of the University of Auckland (AHREC: 1130) and the University of Calgary ethics committee of the University of Calgary (ID: REB19-1925) gave ethical approval for this work All patients provided informed written consent.

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All data produced in the present study are available upon reasonable request to the authors