Postprandial plasma glucose response and gastrointestinal symptom severity in patients with diabetic gastroparesis

Gastrointestinal hormones and regulation of gastric emptying

PURPOSE OF REVIEW

In this review, we evaluate recent findings related to the association between gastrointestinal hormones and regulation of gastric emptying.

RECENT FINDINGS

Motilin and ghrelin, which act during fasting, promote gastric motility, whereas most of the hormones secreted after a meal inhibit gastric motility. Serotonin has different progastric or antigastric motility effects depending on the receptor subtype. Serotonin receptor agonists have been used clinically to treat dyspepsia symptoms but other hormone receptor agonists or antagonists are still under development. Glucagon-like peptide 1 agonists, which have gastric motility and appetite-suppressing effects are used as a treatment for obesity and diabetes.

SUMMARY

Gastrointestinal hormones play an important role in the regulation of gastric motility. Various drugs have been developed to treat delayed gastric emptying by targeting gastrointestinal hormones or their receptors but few have been commercialized.

Chronic mesenteric ischaemia: the importance of the individual mesenteric artery

BACKGROUND

Chronic mesenteric ischaemia (CMI) is a vastly underdiagnosed condition that typically leads to postprandial abdominal pain and weight loss. The aim of the study was to explore the involvement of various mesenteric vessels in total splanchnic blood flow (SBF) and hepatic vein oxygenation.

METHODS

Single-blinded comparative trial of 476 patients clinically suspected of CMI. Routine investigation included measurement of hepatic vein oxygen saturation, indirect measurement of the total splanchnic blood flow (SBF), using Fick's principle and the tracer [^99m Tc]Mebrofenin, before and after a meal, and digital subtraction angiography.

RESULTS

A total of 176 of the 476 patients (36%) had at least one angiographically significant stenosis (lumen reduction ≥70%). In patients with a significant one-vessel disease, the percentage having CMI according to SBF was 10% for a celiac trunk stenosis (n = 60), 50% for a superior mesenteric stenosis (n = 24) and 6% for an inferior mesenteric artery stenosis (n = 34). In patients with a significant two-vessel disease, the percentage with CMI according to SBF response was 92%, 18% and 79%, for no significant stenosis of the celiac trunk (n = 13), superior mesenteric artery (n = 17) and inferior mesenteric artery (n = 19), respectively.

CONCLUSION

Patients with significant one- or two-vessel stenosis involving the superior mesenteric artery have a higher likelihood of CMI according to flow criteria and a greater postprandial decrease in hepatic vein saturation on average than patients with no involvement of the superior mesenteric artery.

Gastrointestinal pain

Gastrointestinal (GI) pain - a form of visceral pain - is common in some disorders, such as irritable bowel syndrome, Crohn's disease and pancreatitis. However, identifying the cause of GI pain frequently represents a diagnostic challenge as the clinical presentation is often blurred by concomitant autonomic and somatic symptoms. In addition, GI pain can be nociceptive, neuropathic and associated with cancer, but in many cases multiple aetiologies coexist in an individual patient. Mechanisms of GI pain are complex and include both peripheral and central sensitization and the involvement of the autonomic nervous system, which has a role in generating the symptoms that frequently accompany pain. Treatment of GI pain depends on the precise type of pain and the primary disorder in the patient but can include, for example, pharmacological therapy, cognitive behavioural therapies, invasive surgical procedures, endoscopic procedures and lifestyle alterations. Owing to the major differences between organ involvement, disease mechanisms and individual factors, treatment always needs to be personalized and some data suggest that phenotyping and subsequent individual management of GI pain might be options in the future.

Pathophysiology and management of diabetic gastroenteropathy

Polyneuropathy is a common complication to diabetes. Neuropathies within the enteric nervous system are associated with gastroenteropathy and marked symptoms that severely reduce quality of life. Symptoms are pleomorphic but include nausea, vomiting, dysphagia, dyspepsia, pain, bloating, diarrhoea, constipation and faecal incontinence. The aims of this review are fourfold. First, to provide a summary of the pathophysiology underlying diabetic gastroenteropathy. Secondly to give an overview of the diagnostic methods. Thirdly, to provide clinicians with a focussed overview of current and future methods for pharmacological and nonpharmacological treatment modalities. Pharmacological management is categorised according to symptoms arising from the upper or lower gut as well as sensory dysfunctions. Dietary management is central to improvement of symptoms and is discussed in detail, and neuromodulatory treatment modalities and other emerging management strategies for diabetic gastroenteropathy are discussed. Finally, we propose a diagnostic/investigation algorithm that can be used to support multidisciplinary management.

Current and Emerging Medical Therapies for Gastroparesis

OPINION STATEMENT

Gastroparesis likely involves various pathophysiological disorders and is increasingly prevalent as complications of surgeries, medications, and chronic diabetes. Key to diagnosis is evidence of delayed gastric emptying, generally based on standardized scintigraphy, and ruling out distal obstruction or other dysmotilities. Initial medical management includes reviewing potentially exacerbating medications and ruling out other reversible causes, achieving tighter glucose control in diabetics, and implementing dietary and lifestyle changes. While current available medications are limited, symptomatic control is aimed at improving gastric emptying, alleviating nausea and vomiting, and treating associated abdominal pain. Other potential therapies are aimed at reducing acid production, improving gastric accommodation or pyloric dysfunction, and treating bacterial overgrowth. Future studies should be aimed toward identification of subpopulations of gastroparetics who are better responders to the various medications based on differences in underlying pathophysiology and adopting standardized study end point measures that may allow for comparisons across trials. This chapter will review current treatment options, upcoming promising medications, and some of the hurdles in advancing the field forward.