Spontaneous or Deliberate: Effects of Acute Variations in Glycemia on Gastric Emptying in Type 1 Diabetes.

Abstract

During the last 30 years, there has been a paradigm shift in knowledge relating to gastric emptying in diabetes, reflecting the application of novel investigative techniques. Scintigraphy, which utilizes radiolabeled solid and/or liquid meals and a γ-camera, remains the gold standard for quantifying gastric emptying (1,2). More recently, stable isotope breath tests, involving measurement of 13CO2 in breath samples after ingestion of a 13C-labeled meal, have been validated against scintigraphy with inherent advantages of simplicity, point-of-care sampling, and avoidance of radiation exposure (1). Key insights in diabetes include the recognition that solids and liquids empty from the stomach differentially and that interindividual variation—already substantial in health (1–4 kcal/min) (2)—is increased in diabetes because emptying is delayed in ∼30–40% of complicated, suboptimally controlled patients attending tertiary centers (2–4), while often modestly accelerated in well-controlled patients with type 1 or type 2 diabetes (2). Upper gastrointestinal symptoms, such as nausea and fullness, occur frequently and impact quality of life adversely, but their relationship to gastric emptying is weak (1–3). Rather than simply being a manifestation of autonomic neuropathy, the pathogenesis of gastroparesis is heterogeneous, involving loss of interstitial cells of Cajal (“pacemaker” cells), an immune infiltrate, and muscle atrophy in addition to changes in intrinsic and extrinsic (vagal) innervation (1). There is a relatively weak relationship between gastroparesis and autonomic dysfunction, as assessed by standardized cardiovascular reflexes (3). Finally, and perhaps most importantly, gastric emptying influences postprandial glycemic excursions, the dominant determinant of HbA1c when the latter is less than ∼64 mmol/mol (8.0%) (5), and emptying can be modulated by dietary or pharmacological approaches (e.g., short-acting glucagon-like peptide 1 receptor agonists or pramlintide) for therapeutic gain (2). Accordingly, gastric emptying is central to the pathogenesis and personalized management of diabetes (6). …