Defining and phenotyping gastric abnormalities in long-term type 1 diabetes using body surface gastric mapping

Abstract

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.

Revised spectral metrics for body surface measurements of gastric electrophysiology

“…To this end, group-level differences have recently been established between symptomatic type 1 diabetics and controls for the GA-RI and Principal Gastric Frequency, and the amplitude. 32 Further studies evaluating the revised metrics in patient populations are the subject of ongoing work.…”

“…the onset and duration of this response. 13,16,32 Therefore, if meal response metrics employ only a brief fixed window (e.g. 21 ), meal responses may be underestimated.…”

“…13,31 However, on visual inspection of 4-h postprandial recordings, we have shown substantial variability in the timing of the onset and duration of the meal response. 13,16,32 As a result, metrics based on an amplitude/power ratio, computing the relative postprandial to preprandial averaged amplitude/power using either the entire postprandial period or a fixed window within the postprandial period, are at risk of missing the meal response or underestimating the gastric response due to inclusion of low-amplitude activity within the selected postprandial window. In EGG, for example, meal response metrics have often been formulated based on the first 30-60 min of the postprandial period alone.…”

Gastric sensorimotor function and its clinical measurement

“…Promising data has recently been reported in this regard, indicating the capability of gastric mapping to separate nausea and vomiting patients into subgroups with neuromuscular abnormalities vs normal electrophysiology, the latter being more likely to experience disorders of gut‐brain interaction 14 . In addition, three studies have now indicated symptom correlations based on gastric mapping phenotypes in nausea and vomiting disorders, FD, and diabetes 14,34,35 …”

“…14 In addition, three studies have now indicated symptom correlations based on gastric mapping phenotypes in nausea and vomiting disorders, FD, and diabetes. 14,34,35 An attraction of body surface gastric mapping is that the emerging disease phenotypes, such as neuromuscular dysfunction, appear to represent more direct mechanisms than higher-order variables such as delayed transit. However, body surface gastric mapping has only recently emerged, and its role in diagnostic and therapeutic pathways will become clearer with further data and development.…”