Physiological hyperglycemia slows gastric emptying in normal subjects and patients with insulin-dependent diabetes mellitus

Antidiabetic actions of endogenous and exogenous GLP-1 in type 1 diabetic patients with and without residual β-cell function

OBJECTIVE

To investigate the effect of exogenous as well as endogenous glucagon-like peptide 1 (GLP-1) on postprandial glucose excursions and to characterize the secretion of incretin hormones in type 1 diabetic patients with and without residual β-cell function.

RESEARCH DESIGN AND METHODS

Eight type 1 diabetic patients with (T1D+), eight without (T1D-) residual β-cell function, and eight healthy matched control subjects were studied during a mixed meal with concomitant infusion of GLP-1 (1.2 pmol/kg/min), saline, or exendin 9-39 (300 pmol/kg/min). Before the meal, half dose of usual fast-acting insulin was injected. Plasma glucose (PG), glucagon, C-peptide, total GLP-1, intact glucose-dependent insulinotropic polypeptide (GIP), free fatty acids, triglycerides, and gastric emptying rate (GE) by plasma acetaminophen were measured.

RESULTS

Incretin responses did not differ between patients and control subjects. Infusion of GLP-1 decreased peak PG by 45% in both groups of type 1 diabetic patients. In T1D+ patients, postprandial PG decreased below fasting levels and was indistinguishable from control subjects infused with saline. In T1D- patients, postprandial PG remained at fasting levels. GLP-1 infusion reduced GE and glucagon levels in all groups and increased fasting C-peptide in T1D+ patients and control subjects. Blocking endogenous GLP-1 receptor action increased endogenous GLP-1 secretion in all groups and increased postprandial glucose, glucagon, and GE in T1D+ and T1D- patients. The insulinogenic index (the ratio of insulin to glucose) decreased in T1D+ patients during blockade of endogenous GLP-1 receptor action.

CONCLUSIONS

Type 1 diabetic patients have normal incretin responses to meals. In type 1 diabetic patients, exogenous GLP-1 decreases peak postprandial glucose by 45% regardless of residual β-cell function. Endogenous GLP-1 regulates postprandial glucose excursions by modulating glucagon levels, GE, and β-cell responsiveness to glucose. Long-term effects of GLP-1 in type 1 diabetic patients should be investigated in future clinical trials.

Plasticity of vagal brainstem circuits in the control of gastrointestinal function

The afferent vagus transmits sensory information from the gastrointestinal (GI) tract and other viscera to the brainstem via a glutamatergic synapse at the level of the nucleus of the solitary tract (NTS). Second order NTS neurons integrate this sensory information with inputs from other CNS regions that regulate autonomic functions and homeostasis. Glutamatergic and GABAergic neurons are responsible for conveying the integrated response to other nuclei, including the adjacent dorsal motor nucleus of the vagus (DMV). The preganglionic neurons in the DMV are the source of the parasympathetic motor response back to the GI tract. The glutamatergic synapse between the NTS and DMV is unlikely to be tonically active in regulating gastric motility and tone although almost all neurotransmitters tested so far modulate transmission at this synapse. In contrast, the tonic inhibitory GABAergic input from the NTS to the DMV appears to be critical in setting the tone of gastric motility and, under basal conditions, is unaffected by many neurotransmitters or neurohormones. This review is based, in part, on a presentation by Dr Browning at the 2009 ISAN meeting in Sydney, Australia and discusses how neurohormones and macronutrients modulate glutamatergic transmission to NTS neurons and GABAergic transmission to DMV neurons in relation to sensory information that is received from the GI tract. These neurohormones and macronutrients appear to exert efficient "on-demand" control of the motor output from the DMV in response to ever-changing demands required to maintain homeostasis.

Gastroparesis: approach, diagnostic evaluation, and management

Gastroparesis is a chronic motility disorder of the stomach that involves delayed emptying of solids and liquids, without evidence of mechanical obstruction. Although no cause can be determined for the majority of cases, the disease often develops as a complication of abdominal surgeries or because of other underlying disorders, such as diabetes mellitus or scleroderma. The pathophysiology behind delayed gastric emptying is still not well-understood, but encompasses abnormalities at 3 levels--autonomic nervous system, smooth muscle cells, and enteric neurons. Patients will often cite nausea, vomiting, postprandial fullness, and early satiety as their most bothersome symptoms on history and physical examination. Those that present with severe disease may already have developed complications, such as the formation of bezoars or masses of undigested food. In patients suspected of gastroparesis, diagnostic evaluation requires an initial upper endoscopy to rule out mechanical causes, followed by a gastric-emptying scintigraphy for diagnosis. Other diagnostic alternatives would be wireless capsule motility, antroduodenal manometry, and breath testing. Once gastroparesis is diagnosed, dietary modifications, such as the recommendation of more frequent and more liquid-based meals, are encouraged. Promotility medications like erythromycin and antiemetics like prochlorperazine are offered for symptomatic relief. These agents may be frequently changed, as the right combination of effective medications will vary with each individual. In patients who are refractory to pharmacologic treatment, more invasive options, such as intrapyloric botulinum toxin injections, placement of a jejunostomy tube, or implantation of a gastric stimulator, are considered. Future areas of research are based on current findings from clinical studies. New medications, such as hemin therapy, are emerging because of a better understanding of the pathophysiology behind gastroparesis, and present treatment options, such as gastric electric stimulation, are evolving to be more effective. Regenerative medicine and stem cell-based therapies also hold promise for gastroparesis in the near future.

The once-daily human glucagon-like peptide-1 (GLP-1) analog liraglutide improves postprandial glucose levels in type 2 diabetes patients

INTRODUCTION

Fasting and postprandial plasma glucose (FPG, PPG) control are both necessary to achieve glycosylated hemoglobin (HbA(1c)) regulation goals. Liraglutide, based on its glucagon-like peptide 1 (GLP-1)-mediated pharmacology and pharmacokinetics may reduce HbA(1c) through both FPG and PPG levels. The objective of the present study was to investigate the effect of once-daily liraglutide (0.6, 1.2, and 1.8 mg) at steady state on FPG, PPG, postprandial insulin, and gastric emptying.

METHODS

Eighteen subjects with type 2 diabetes, aged 18-70 years, with a body mass index of 18.5-40 kg/m(2) and HbA(1c) of 7.0%-9.5% were included in this single-centre, randomized, placebo-controlled, double-blind, two-period, cross over trial. Patients were randomized into two groups (A or B). Group A received oncedaily liraglutide for 3 weeks, followed by a 3-4-week washout period and 3 weeks of oncedaily placebo. Group B was treated as for Group A, but treatment periods were reversed (ie, placebo followed by liraglutide). A meal test was performed at steady-state liraglutide/placebo doses of 0.6, 1.2, and 1.8 mg/day. Plasma glucose, insulin, and paracetamol (acetaminophen) concentrations (to assess gastric emptying) were measured pre- and postmeal.

RESULTS

PPG levels significantly decreased (P<0.001) after all three liraglutide doses when compared with placebo. This decrease was also apparent when corrected for baseline (incremental excursions), with the exception of average incremental increase calculated as area under the concentration curve (AUC) over the fasting value from time zero to 5 hours (iAUC (0-5 h)/5 hours) after liraglutide 0.6 mg, where there was a trend to decrease (P=0.082). In addition, FPG levels significantly decreased at all three liraglutide dose levels when compared to placebo (P<0.001). Fasting and postprandial insulin levels significantly increased with liraglutide versus placebo at all doses studied (P<0.001). A significant delay in gastric emptying during the first hour postmeal was observed at the two highest liraglutide doses versus placebo.

CONCLUSION

In addition to lowering FPG levels, liraglutide improves PPG levels (absolute and incremental) possibly by both stimulating postprandial insulin secretion and delaying gastric emptying.

Gastroparesis in pregnancy: case report and literature review

Gastroparesis is a syndrome characterized by delayed gastric emptying in the absence of mechanical obstruction. The most common underlying aetiology is diabetes mellitus; however, many cases are idiopathic. Pregnancy per se is associated with gastrointestinal neuromuscular dysfunction; however, reports of gastroparesis arising during pregnancy are rare. We report a case of severe gastroparesis and proximal small bowel paresis presenting during pregnancy.

Diabetic gastroparesis-backwards and forwards

Diabetic gastroparesis was once thought to be rare, associated with a poor prognosis, and to affect only patients with type 1 diabetes and irreversible autonomic neuropathy. A landmark study conducted by Horowitz et al. and published in JGH in 1986 paved the way for further studies to examine the pathophysiology, natural history and prognosis of diabetic gastroparesis, as well as its optimal management. This review summarizes the developments in knowledge gained over the last ∼25 years that have led to understanding about normal and disordered gastric emptying in diabetes, with a particular emphasis on the inter-relationship between the rate of gastric emptying and the regulation of blood glucose.

Effects of GLP-1 and incretin-based therapies on gastrointestinal motor function

Glucagon-like peptide 1 (GLP-1) is a hormone secreted predominantly by the distal small intestine and colon and released in response to enteral nutrient exposure. GLP-1-based therapies are now used widely in the management of type 2 diabetes and have the potential to be effective antiobesity agents. Although widely known as an incretin hormone, there is a growing body of evidence that GLP-1 also acts as an enterogastrone, with profound effects on the gastrointestinal motor system. Moreover, the effects of GLP-1 on gastrointestinal motility appear to be pivotal to its effect of reducing postprandial glycaemic excursions and may, potentially, represent the dominant mechanism. This review summarizes current knowledge of the enterogastrone properties of GLP-1, focusing on its effects on gut motility at physiological and pharmacological concentrations, and the motor actions of incretin-based therapies. While of potential importance, the inhibitory action of GLP-1 on gastric acid secretion is beyond the scope of this paper.

Gastrointestinal hormonal dysfunction in gastroparesis and functional dyspepsia

BACKGROUND

Numerous hormones secreted by the gut, during both the fasted state and in response to a meal, influence gastrointestinal motor and/or sensory function, and appear to contribute to the pathogenesis of delayed gastric emptying associated with gastroparesis, functional dyspepsia (FD) and feed intolerance in critical illness. Gut hormones are, accordingly, potential targets for the management of these patients.

PURPOSE

This article will discuss the hypersensitivity to enteral fat and endogenous (nutrient-stimulated) and exogenous cholecystokinin (CCK) in patients with FD, and the elevation in both fasting and postprandial CCK levels evident in this group. It will review the use of pharmacological agonists of motilin and ghrelin, which accelerate gastric emptying, in the management of gastroparesis and FD. The frequent finding of markedly delayed gastric emptying in the critically ill will be examined; this is associated with elevated plasma CCK and peptide YY in both the fasted and postprandial states, which may account for the increase in small intestinal nutrient inhibitory feedback on gastric motility in this group. The concepts that the rate of gastric emptying is a major determinant of postprandial glycemic excursions in diabetes, and that modulation of gastric emptying may improve glycemic control, will be addressed; in type 1 and insulin-treated type 2 diabetic patients, co-ordination of insulin administration with nutrient delivery and absorption should be optimized, while type 2 patients who are not on insulin are likely to respond to dietary and/or pharmacological interventions which slow gastric emptying.

Effects of metoclopramide on duodenal motility and flow events, glucose absorption, and incretin hormone release in response to intraduodenal glucose infusion

The contribution of small intestinal motor activity to nutrient absorption is poorly defined. A reduction in duodenal flow events after hyoscine butylbromide, despite no change in pressure waves, was associated with reduced secretion of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and a delay in glucose absorption. The aim of this study was to investigate the effect of metoclopramide on duodenal motility and flow events, incretin hormone secretion, and glucose absorption. Eight healthy volunteers (7 males and 1 female; age 29.8 ± 4.6 yr; body mass index 24.5 ± 0.9 kg/m²) were studied two times in randomized order. A combined manometry and impedance catheter was used to measure pressure waves and flow events in the same region of the duodenum simultaneously. Metoclopramide (10 mg) or control was administered intravenously as a bolus, followed by an intraduodenal glucose infusion for 60 min (3 kcal/min) incorporating the ¹⁴C-labeled glucose analog 3-O-methylglucose (3-OMG). We found that metoclopramide was associated with more duodenal pressure waves and propagated pressure sequences than control (P < 0.05 for both) during intraduodenal glucose infusion. However, the number of duodenal flow events, blood glucose concentration, and plasma 3-[¹⁴C]OMG activity did not differ between the two study days. Metoclopramide was associated with increased plasma concentrations of GLP-1 (P < 0.05) and GIP (P = 0.07) but lower plasma insulin concentrations (P < 0.05). We concluded that metoclopramide was associated with increased frequency of duodenal pressure waves but no change in duodenal flow events and glucose absorption. Furthermore, GLP-1 and GIP release increased with metoclopramide, but insulin release paradoxically decreased.

Diabetic gastroparesis and its impact on glycemia

Diabetes is the most common cause of gastroparesis and it is now recognized that the relationship between gastric emptying and glycemia is complex and intertwined. Postprandial blood glucose levels influence, and are influenced by, the rate of gastric emptying, highlighting the difficulty in determining which is the cause and which is the effect. Novel diagnostic techniques and therapeutic strategies have been developed for the management of diabetic gastroparesis. This article highlights recent advances in knowledge about diabetic gastroparesis, with an emphasis on the inter-relationships between disordered gastric motor function on glycemia and vice versa, as well as therapeutic strategies for optimizing glycemic control using modulation of gastric emptying.

Gastric emptying of hexose sugars: role of osmolality, molecular structure and the CCK₁ receptor

BACKGROUND

It is widely reported that hexose sugars slow gastric emptying (GE) via osmoreceptor stimulation but this remains uncertain. We evaluated the effects of a panel of hexoses of differing molecular structure, assessing the effects of osmolality, intra-individual reproducibility and the role of the CCK(1) receptor, in the regulation of GE by hexoses.

METHODS

Thirty one healthy non-obese male and female subjects were studied in a series of protocols, using a (13) C-acetate breath test to evaluate GE of varying concentrations of glucose, galactose, fructose and tagatose, with water, NaCl and lactulose as controls. GE was further evaluated following the administration of a CCK(1) receptor antagonist. Three subjects underwent repeated studies to evaluate intra-individual reproducibility.

KEY RESULTS

At 250 mOsmol, a hexose-specific effect was apparent: tagatose slowed GE more potently than water, glucose and fructose (P < 0.05). Fructose (P < 0.05) also slowed GE, but with substantial inter-, but not intra-, individual differences. As osmolality increased further the hexose-specific differences were lost. At 500 mOsmol, all hexoses slowed GE compared with water (P < 0.05), whereas lactulose and saline did not. The slowing of GE by hexose sugars appeared to be CCK(1) receptor-dependent.

CONCLUSIONS & INFERENCES

The effects of hexose sugars on GE appear related to their molecular structure rather than osmolality per se, and are, at least in part, CCK(1) receptor-dependent.

Do HbA1C Levels Correlate With Delayed Gastric Emptying in Diabetic Patients?

Background/Aims

Gastroparesis is characterized by delayed gastric emptying without obstruction. Diabetes is frequently associated with poor glycemic control and delayed gastric emptying. Gastric emptying scintigraphy (GES) is the standard for measuring gastric emptying. Serum hemoglobin A1C (HbA1C) measures prolonged glycemic control with normal as < 7% glycated. To date, no correlation of serum HbA1C level with gastric emptying, demonstrated by GES, in diabetics has been performed. The aim of the present investigation is to determine if a relationship exists between serum HbA1C levels and gastric emptying, assessed by GES, in diabetics.

Methods

All diabetics, having both GES and serum HbA1C level within 3 months from July 1, 2003 - June 30, 2008 were eligible for study. Demographic data collected included gender, age and ethnicity. Abnormal gastric emptying was defined as T½ > 120 minutes and serum HbA1C as percent glycated.

Results

Nuclear Medicine GES database review revealed 431 examinations performed during the study interval. A total of 181 were not eligible due to the following: 29 duplicates, 22 diabetes not documented and 130 without HbA1C levels, resulting a study group of 250 cases. No significant correlation was observed between gastric emptying time, HbA1C or age. Among patients with HbA1C ≥ 7%, HbA1C was inversely related to age with a coefficient of correlation of r = -0.175 (p = 0.038).

Conclusions

There is no correlation observed between gastric emptying time, using GES, and serum HbA1C levels. In diabetics, serum HbA1C is not as important as daily glycemic control regarding gastric emptying.

Gastrointestinal symptoms in adolescents with type 1 diabetes

OBJECTIVE

To compare the prevalence of gastrointestinal (GI) symptoms in adolescents with and without type 1 diabetes (T1DM) and to relate the symptoms in patients to demographic, socioeconomic, diabetes-specific variables, and food habits.

METHOD

In a population-based, cross-sectional setting, 173 adolescents with T1DM and 160 matched controls completed a questionnaire. Moreover, 13 patients and 1 control were excluded due to having a GI disorder.

RESULTS

Moreover, 75% of patients and 77% of controls reported at least one GI symptom (ns). More girls than boys reported symptoms. Reflux episodes were more prevalent in patients with poorer socioeconomic status. Poor appetite, loss of weight, an uncomfortable feeling of fullness, swallowing difficulties, and nausea were more prevalent in patients smoking daily compared with patients not smoking daily. Vomiting was more prevalent in patients with duration of diabetes >7 yr, and patients with reflux episodes had higher glycated hemoglobin (HbA1c). Belching and early satiety were more prevalent in patients with an irregular meal pattern.

CONCLUSIONS

GI symptoms in adolescents are common, but the prevalence is not increased in those with T1DM. GI symptoms in adolescents with T1DM are associated with female sex, poorer socioeconomic status, daily cigarette smoking, longer duration of diabetes, poorer metabolic control, and an irregular meal pattern.

Effects of exogenous glucagon-like peptide-1 on gastric emptying and glucose absorption in the critically ill: relationship to glycemia

OBJECTIVE

To determine the acute effects of exogenous glucagon-like peptide-1 on gastric emptying, glucose absorption, glycemia, plasma insulin, and glucagon in critically ill patients.

DESIGN

Randomized, double-blind, crossover study.

SETTING

Intensive care unit.

SUBJECTS

Twenty-five mechanically ventilated patients, without known diabetes, studied on consecutive days.

INTERVENTIONS

Intravenous glucagon-like peptide-1 (1.2 pmol/kg/min) or placebo was infused between -30 and 330 mins. At 0 min, 100 mL liquid nutrient (1 kcal/mL) including 100 microg of 13C-octanoic acid and 3 grams of 3-O-methyl-glucose was administered.

MEASUREMENTS AND MAIN RESULTS

Blood glucose, serum 3-O-methyl-glucose (as an index of glucose absorption), insulin and glucagon concentrations, as well as exhaled 13CO2 were measured. The gastric emptying coefficient was calculated to quantify gastric emptying. Data are presented as mean (sd). There was a nonsignificant trend for glucagon-like peptide-1 to slow gastric emptying (gastric emptying coefficient) (glucagon-like peptide-1, 2.45 [0.93] vs. placebo, 2.75 [0.83]; p = .09). In 11 of the 25 patients, gastric emptying was delayed during placebo infusion and glucagon-like peptide-1 had no detectable effect on gastric emptying in this group (1.92 [0.82] vs. 1.90 [0.68]; p = .96). In contrast, in patients who had normal gastric emptying during placebo, glucagon-like peptide-1 slowed gastric emptying substantially (2.86 [0.58] vs. 3.41 [0.37]; p = .006). Glucagon-like peptide-1 markedly reduced the rate of glucose absorption (3-O-methyl-glucose area under the curve(0-330), 37 [35] vs. 76 [51] mmol/L/min; p < .001), decreased preprandial glucagon (at 0 min change in glucagon, -15 [15] vs. -3 [14] pmol/L; p < .001), increased the insulin/glucose ratio throughout the infusion (area under the curve(-30-330), 1374 [814] vs. 1172 [649] mU/mmol/min; p = .041), and attenuated the glycemic response to the meal (glucose area under the curve(0-330), 2071 [353] vs. 2419 [594] mmol/L/min; p = .001).

CONCLUSIONS

Exogenous glucagon-like peptide-1 lowers postprandial glycemia in the critically ill. This may occur, at least in part, by slowing gastric emptying when the latter is normal but not when it is delayed.

Evaluation of gastrointestinal motility in awake rats: a learning exercise for undergraduate biomedical students

Current medical curricula devote scarce time for practical activities on digestive physiology, despite frequent misconceptions about dyspepsia and dysmotility phenomena. Thus, we designed a hands-on activity followed by a small-group discussion on gut motility. Male awake rats were randomly submitted to insulin, control, or hypertonic protocols. Insulin and control rats were gavage fed with 5% glucose solution, whereas hypertonic-fed rats were gavage fed with 50% glucose solution. Insulin treatment was performed 30 min before a meal. All meals (1.5 ml) contained an equal mass of phenol red dye. After 10, 15, or 20 min of meal gavage, rats were euthanized. Each subset consisted of six to eight rats. Dye recovery in the stomach and proximal, middle, and distal small intestine was measured by spectrophotometry, a safe and reliable method that can be performed by minimally trained students. In a separate group of rats, we used the same protocols except that the test meal contained (99m)Tc as a marker. Compared with control, the hypertonic meal delayed gastric emptying and gastrointestinal transit, whereas insulinic hypoglycemia accelerated them. The session helped engage our undergraduate students in observing and analyzing gut motor behavior. In conclusion, the fractional dye retention test can be used as a teaching tool to strengthen the understanding of basic physiopathological features of gastrointestinal motility.

Effects of intravenous fructose on gastric emptying and antropyloroduodenal motility in healthy subjects

Gastric emptying (GE) of glucose is regulated closely, not only as a result of inhibitory feedback arising from the small intestine, but also because of the resulting hyperglycemia. Fructose is used widely in the diabetic diet and is known to empty from the stomach slightly faster than glucose but substantially slower than water. The aims of this study were to determine whether intravenous (iv) fructose affects GE and antropyloroduodenal motility and how any effects compare to those induced by iv glucose. Six healthy males (age: 26.7 +/- 3.8 yr) underwent concurrent measurements of GE of a solid meal (100 g ground beef labeled with 20 MBq (99m)Tc-sulfur colloid) and antropyloroduodenal motility on three separate days in randomized order during iv infusion of either fructose (0.5 g/kg), glucose (0.5 g/kg), or isotonic saline for 20 min. GE (scintigraphy), antropyloroduodenal motility (manometry), and blood glucose (glucometer) were measured for 120 min. There was a rise in blood glucose (P < 0.001) after iv glucose (peak 16.4 +/- 0.6 mmol/l) but not after fructose or saline. Intravenous glucose and fructose both slowed GE substantially (P < 0.005 for both), without any significant difference between them. Between t = 0 and 30 min, the number of antral pressure waves was less after both glucose and fructose (P < 0.002 for both) than saline, and there were more isolated pyloric pressure waves during iv glucose (P = 0.003) compared with fructose and saline (P = NS for both) infusions. In conclusion, iv fructose slows GE and modulates gastric motility in healthy subjects, and the magnitude of slowing of GE is comparable to that induced by iv glucose.

Mechanisms of gastric emptying disturbances in chronic and acute inflammation of the distal gastrointestinal tract

It is unclear why patients with inflammation of the distal bowel complain of symptoms referable to the upper gastrointestinal tract, specifically to gastric emptying (GE) disturbances. Thus we aimed to determine occurrence and putative pathomechanisms of gastric motor disorders in such patients. Thirteen healthy subjects (CON), 13 patients with Crohn's disease (CD), 10 with ulcerative colitis (UC), and 7 with diverticulitis (DIV) underwent a standardized (13)C-octanoic acid gastric emptying breath test. Plasma glucose, CCK, peptide YY, and glucagon-like peptide-1 (GLP-1) were measured periodically and correlated with GE parameters. Results were given in means +/- SD. Compared with CON, GE half time (T) was prolonged by 50% in CD (115 +/- 55 vs. 182 +/- 95 min, P = 0.037). Six CD, 2 DIV, and 2 UC patients had pathological T (>200 min). Postprandial plasma glucose was increased in all patients but was highest in DIV and correlated with T (r = 0.90, P = 0.006). In CD, mean postprandial CCK levels were increased threefold compared with CON (6.5 +/- 6.7 vs. 2.1 +/- 0.6 pmol/l, P = 0.027) and were correlated with T (r = 0.60, P = 0.041). Compared with CON, GLP-1 levels were increased in UC (25.1 +/- 5.2 vs. 33.5 +/- 13.0 pmol/l, P = 0.046) but markedly decreased in DIV (9.6 +/- 5.2 pmol/l, P < 0.0001). We concluded that a subset of patients with CD, UC, or DIV has delayed GE. GE disturbances are most pronounced in CD and might partly be caused by excessive CCK release. In DIV there might be a pathophysiological link between decreased GLP-1 release, postprandial hyperglycemia, and delayed GE. These explorative data encourage further studies in larger patient groups.

The nitric oxide synthase inhibitor, Ng-nitro-L-arginine-methyl-ester, attenuates the delay in gastric emptying induced by hyperglycaemia in healthy humans

The aim of this study was to determine whether the nitric oxide (NO) synthase inhibitor, N(g)-nitro-L-arginine-methyl-ester (L-NAME), reverses the effects of acute hyperglycaemia on gastric emptying and antropyloroduodenal (APD) motility. The study had a four-way randomized crossover (hyperglycaemia vs euglycaemia; L-NAME vs placebo) design in a clinical laboratory setting. Seven healthy volunteers [four males; age 30.3 +/- 3.8 years; body mass index (BMI) 23.6 +/- 1.2 kg m(-2)] were the study subjects. After positioning a transnasal manometry catheter across the pylorus, the blood glucose concentration was maintained at either 15 or 5 mmol L(-1) using a glucose/insulin clamp. An intravenous infusion of L-NAME (180 microg kg(-1 )h(-1)) or placebo (0.9% saline) was commenced (T = -30 min) and continued for 150 min. At T = -2 min, subjects ingested a drink containing 50 g of glucose made up to 300 mL with water. Gastric emptying was measured using 3D ultrasound, and APD motility using manometry. Hyperglycaemia slowed gastric emptying (P < 0.05), and this effect was abolished by L-NAME. L-NAME had no effect on gastric emptying during euglycaemia. Hyperglycaemia suppressed fasting antral motility [motility index: 3.9 +/- 0.8 (hyperglycaemia) vs 6.5 +/- 0.6 (euglycaemia); P < 0.01]; l-NAME suppressed postprandial antral motility [motility index: 3.6 +/- 0.2 (L-NAME) vs 5.1 +/- 0.2 (placebo); P < 0.001]. Postprandial basal pyloric pressure was higher during hyperglycaemia (P < 0.001), and lower after administration of L-NAME (P < 0.001). Slowing of gastric emptying induced by hyperglycaemia is mediated by NO, and may involve the modulation of tonic pyloric activity.

Impaired glucose and nutrient absorption in critical illness: is gastric emptying only a piece of the puzzle?

This commentary highlights the contribution of the article by Chapman and colleagues assessing the relationships between glucose absorption, glycaemia and gastric emptying during critical illness. In addition to several more expected findings, their data suggest that factors other than slow gastric emptying may limit glucose absorption during critical illness. This hypothesis has received little attention so far, although numerous small intestinal abnormalities possibly interfering with absorption are known to occur in intensive care patients. Future work should focus on further validation of tools to assess nutrient absorption in the critically ill, before defining the precise causes and mechanisms that are involved.

Gastroparesis: current concepts and management

Delayed gastric emptying in the absence of mechanical obstruction is referred to as gastroparesis. Symptoms that are often attributed to gastroparesis include postprandial fullness, nausea, and vomiting. Although tests of gastric motor function may aid diagnostic labeling, their contribution to determining the treatment approach is often limited. Although clinical suspicion of gastroparesis warrants the exclusion of mechanical causes and serum electrolyte imbalances, followed by empirical treatment with a gastroprokinetic such as domperidone or metoclopramide, evidence that these drugs are effective for patients with gastroparesis is far from overwhelming. In refractory cases with severe weight loss, invasive therapeutics such as inserting a feeding jejunostomy tube, intrapyloric injection of botulinum toxin, surgical (partial) gastrectomy, and implantable gastric electrical stimulation are occasionally considered.

Diabetes mellitus and gastric emptying: questions and issues in clinical practice

It is long known that both type 1 and type 2 diabetes can be associated with changes in gastric emptying; a number of publications have linked diabetes to delayed gastric emptying of variable severity and often with poor relationship to gastrointestinal symptomatology. In contrast, more recent studies have reported accelerated gastric emptying when adjusted for glucose concentration in patients with diabetes, indicating a reciprocal relationship between gastric emptying and ambient glucose concentrations. This review proposes that gastroparesis or gastroparesis diabeticorum, a severe condition characterized by a significant impairment of gastric emptying accompanied by severe nausea, vomiting, and malnutrition, is often overdiagnosed and not well contrasted with delays in gastric emptying. The article offers a clinically relevant definition of gastroparesis that should help differentiate this rare condition from (often asymptomatic) delays in gastric emptying. The fact that delayed gastric emptying can also be observed in non-diabetic individuals under experimental conditions in which hyperglycaemia is artificially induced suggests that a delay in gastric emptying rate when blood glucose concentrations are high is actually an appropriate physiological response to hyperglycaemia, slowing further increases in blood glucose. The article discusses the strengths and weaknesses of various methodologies for assessing gastric emptying, especially with respect to the diabetes population, and reviews newer diabetes therapies that decelerate the rate of gastric emptying. These therapies may be a beneficial tool in managing postprandial hyperglycaemia because they attenuate rapid surges in glucose concentrations by slowing the delivery of meal-derived glucose.

Delayed radionucleotide gastric emptying studies predict morbidity in diabetics with symptoms of gastroparesis

BACKGROUND & AIMS

The aim of this study was to evaluate the prognostic value of gastric emptying studies on the morbidity associated with diabetic gastroparesis.

METHODS

This was a parallel cohort study of 3 groups. Group A (n = 94) contained diabetic patients (type 1 and type 2) with classic symptoms of gastroparesis (including early satiety, postprandial fullness, bloating, abdominal swelling, nausea, vomiting, and retching) and delay in radionucleotide gastric emptying study. Group B (n = 94) contained diabetic subjects with classic symptoms of gastroparesis but negative scintigraphy. Group C (n = 94) contained diabetic subjects without symptoms of gastroparesis. Data were gathered on the number of days hospitalized and hospitalizations, office visits, emergency department visits, death rate, glycosylated hemoglobin levels, medications, and past medical history.

RESULTS

Group A had significantly more hospital days per 1000 patient days (25.5) than both group B (5.1; P < .01) and group C (2.3; P < .01). Group A also had significantly more hospitalizations, office visits, and emergency department visits than both group B and group C. Deaths and mean glycosylated hemoglobin levels did not differ between the groups. Patients in group A were more likely to have cardiovascular disease (19.2% vs 6.4%, A vs C; P < .05), hypertension (63% vs 43%, A vs C; P = .005), and retinopathy (33% vs 11.7%, A vs C; P < .001).

CONCLUSIONS

A delayed radionucleotide gastric emptying study predicts negative health outcomes in diabetic patients with symptoms of gastroparesis. We identified a correlation between diabetic gastroparesis and cardiovascular disease, hypertension, and retinopathy that may indicate an underlying vascular etiology.

Insulin resistance after cardiopulmonary bypass in the elderly patient

OBJECTIVES

Preoperative carbohydrate administration attenuates insulin resistance. We studied effects of preoperative oral carbohydrate loading in elderly patients undergoing coronary artery bypass grafting.

DESIGN

Eighteen patients were assigned either to get a carbohydrate drink or to be controls. Perioperatively, glucose was administered. A gastric emptying test was performed. Glucose and insulin concentrations were measured. Levels of glucose, insulin and stress hormones were studied pre-, per- and postoperatively.

RESULTS AND DISCUSSION

Preoperative carbohydrate loading did not affect stress hormones. Gastric residual after the carbohydrate drink was 11+/-3% (mean+/-SEM). Glucose concentration was lower before anaesthesia induction in the carbohydrate group, possibly due to increased insulin release. Insulin levels differed at baseline, induction and day six. All patients returned to baseline on day six.

CONCLUSIONS

The study group was insulin resistant on postoperative day one and two. The effects were explainable by the traumatic stress response. No adverse effect was noted from the carbohydrate drink. If glucose is administered intravenously during surgery, there is no obvious advantage of preoperative carbohydrate loading on insulin resistance or stress hormone response.

Diabetic gastroparesis: diagnosis and management

Gastric emptying is frequently abnormal in patients with long-standing type 1 and type 2 diabetes mellitus. Symptoms commonly associated with disordered gastric emptying include nausea, vomiting, bloating and epigastric pain, while patients are also at risk of malnutrition, weight loss, impaired drug absorption, disordered glycaemic control and poor quality of life. Although often attributed to the presence of irreversible autonomic neuropathy, acute hyperglycaemia represents a potentially reversible cause of gastric dysfunction in diabetes. Scintigraphy represents the gold standard for measuring gastric emptying. The management of diabetic gastroparesis is less than optimal, partly because the pathogenesis has not been clearly defined. Treatment approaches include dietary modification and optimization of glycaemia, and the use of prokinetic drugs, while novel therapies such as gastric electrical stimulation are the subject of ongoing investigation.

Pathophysiology and management of gastroparesis

Gastroparesis is characterized by upper gastrointestinal symptoms associated with delayed gastric emptying, without mechanical obstruction. However, symptoms do not correlate well with the magnitude of delay in gastric emptying. Diabetes mellitus and surgery are the most common causes, although more than 30% of cases are idiopathic. Coordination of insulin action with nutrient delivery is important in diabetics, as postprandial blood glucose levels and gastric emptying are interdependent, and gastroparesis probably represents a major cause of poor glycemic control. Scintigraphy is the gold standard for measuring gastric emptying. Current treatment mainly involves the use of prokinetic drugs. Pyloric botulinum toxin injection and gastric electrical stimulation require more evidence from controlled studies before their use can be recommended. Surgical options remain inadequately studied.

Pramlintide in the treatment of diabetes mellitus

Pramlintide, the first member of a new class of drugs for the treatment of insulin-using patients with type 2 or type 1 diabetes mellitus, is an analog of the peptide hormone amylin. Amylin is co-secreted with insulin from pancreatic beta cells and acts centrally to slow gastric emptying, suppress postprandial glucagon secretion, and decrease food intake. These actions complement those of insulin to regulate blood glucose concentrations. Amylin is relatively deficient in patients with type 2 diabetes, depending on the severity of beta-cell secretory failure, and is essentially absent in patients with type 1 diabetes. Through mechanisms similar to those of amylin, pramlintide improves overall glycemic control, reduces postprandial glucose levels, and reduces bodyweight in patients with diabetes using mealtime insulin. Reductions in postprandial glucose and bodyweight are important, since postprandial hyperglycemia is associated with an increased risk of microvascular and macrovascular complications, and increased weight is an independent risk factor for cardiovascular disease. Pramlintide is generally well tolerated, with the most frequent treatment-emergent adverse event being mild to moderate nausea, which decreases over time. Pramlintide treatment is also associated with improvements in markers of oxidative stress and cardiovascular risk and improved patient-reported treatment satisfaction. These factors make pramlintide an attractive option for the treatment of postprandial hyperglycemia in patients with diabetes using mealtime insulin.

Glucose absorption and gastric emptying in critical illness

INTRODUCTION

Delayed gastric emptying occurs frequently in critically ill patients and has the potential to adversely affect both the rate, and extent, of nutrient absorption. However, there is limited information about nutrient absorption in the critically ill, and the relationship between gastric emptying (GE) and absorption has hitherto not been evaluated. The aim of this study was to quantify glucose absorption and the relationships between GE, glucose absorption and glycaemia in critically ill patients.

METHODS

Studies were performed in nineteen mechanically-ventilated critically ill patients and compared to nineteen healthy subjects. Following 4 hours fasting, 100 ml of Ensure, 2 g 3-O-methyl glucose (3-OMG) and 99mTc sulphur colloid were infused into the stomach over 5 minutes. Glucose absorption (plasma 3-OMG), blood glucose levels and GE (scintigraphy) were measured over four hours. Data are mean +/- SEM. A P-value < 0.05 was considered significant.

RESULTS

Absorption of 3-OMG was markedly reduced in patients (AUC240: 26.2 +/- 18.4 vs. 66.6 +/- 16.8; P < 0.001; peak: 0.17 +/- 0.12 vs. 0.37 +/- 0.098 mMol/l; P < 0.001; time to peak; 151 +/- 84 vs. 89 +/- 33 minutes; P = 0.007); and both the baseline (8.0 +/- 2.1 vs. 5.6 +/- 0.23 mMol/l; P < 0.001) and peak (10.0 +/- 2.2 vs. 7.7 +/- 0.2 mMol/l; P < 0.001) blood glucose levels were higher in patients; compared to healthy subjects. In patients; 3-OMG absorption was directly related to GE (AUC240; r = -0.77 to -0.87; P < 0.001; peak concentrations; r = -0.75 to -0.81; P = 0.001; time to peak; r = 0.89-0.94; P < 0.001); but when GE was normal (percent retention240 < 10%; n = 9) absorption was still impaired. GE was inversely related to baseline blood glucose, such that elevated levels were associated with slower GE (ret 60, 180 and 240 minutes: r > 0.51; P < 0.05).

CONCLUSIONS

In critically ill patients; (i) the rate and extent of glucose absorption are markedly reduced; (ii) GE is a major determinant of the rate of absorption, but does not fully account for the extent of impaired absorption; (iii) blood glucose concentration could be one of a number of factors affecting GE.

Impaired hyperglycemia-induced delay in gastric emptying in patients with type 1 diabetes deficient for islet amyloid polypeptide

OBJECTIVE

Slowing of gastric emptying by hyperglycemia, a physiological response to minimize postprandial hyperglycemia, may be impaired in patients with type 1 diabetes. The causes and consequences on glucose homeostasis are unknown.

RESEARCH DESIGN AND METHODS

Consequences of euglycemia- and hyperglycemia-induced changes in gastric emptying on postprandial glucose fluxes and excursions were studied in 10 healthy subjects and 15 type 1 diabetic subjects after ingestion of a mixed meal using the double isotope approach ([6,6-(2)H(2)] and [1-(13)C]glucose) and scintigraphic measurements of gastric emptying.

RESULTS

Gastric emptying was greater in type 1 diabetic subjects (90-120 min, P < 0.03), and 50% retention times were comparable in healthy subjects and type 1 diabetic subjects (167 +/- 8 vs. 152 +/- 10, P = 0.32). Hyperglycemia markedly delayed gastric emptying in healthy subjects but did not alter it in type 1 diabetic subjects (50% retention time 222 +/- 18 vs. 167 +/- 8 min, P = 0.003 and 148 +/- 9 vs. 152 +/- 10 min, P = 0.51). Plasma islet amyloid polypeptide (IAPP) increased approximately fourfold in healthy subjects (P < 0.001), whereas it was undetectable in type 1 diabetic subjects. IAPP replacement, using the analog pramlintide, in type 1 diabetic subjects slowed gastric emptying to a comparable extent, as did hyperglycemia in healthy subjects (P < 0.14), and greatly reduced postprandial hyperglycemia (P < 00.1). Meal-derived glucose appearance in plasma (10.7 +/- 0.5 vs. 6.8 +/- 0.7 mumol . kg(-1) . min(-1), P < 0.001) was reduced, and splanchnic glucose sequestration increased (14.0 +/- 3.0 vs. 25.0 +/- 6.0%, P = 0.04).

CONCLUSIONS

In patients with type 1 diabetes the ability to delay gastric emptying in response to hyperglycemia is impaired. This impairment contributes to exaggerated rates of meal-derived glucose appearance and, ultimately, postprandial glucose excursions.

The effect of dipeptidyl peptidase-4 inhibition on gastric volume, satiation and enteroendocrine secretion in type 2 diabetes: a double-blind, placebo-controlled crossover study

OBJECTIVES

The incretin hormone glucagon-like peptide-1 (GLP-1) retards gastric emptying and decreases caloric intake. It is unclear whether increased GLP-1 concentrations achieved by inhibition of the inactivating enzyme dipeptidyl peptidase-4 (DPP-4) alter gastric volumes and satiation in people with type 2 diabetes.

METHODS

In a double-blind, placebo-controlled crossover design, 14 subjects with type 2 diabetes received vildagliptin (50 mg bid) or placebo for 10 days in random order separated by a 2-week washout. On day 7, fasting and postmeal gastric volumes were measured by a (99m)Tc single-photon emission computed tomography (SPECT) method. On day 8, a liquid Ensure meal was consumed at 30 ml/min, and maximum tolerated volume (MTV) and symptoms 30 min later were measured using a visual analogue scale (VAS) to assess effects on satiation. On day 10, subjects ingested water until maximum satiation was achieved. The volume ingested was recorded and symptoms similarly measured using a VAS.

RESULTS

Vildagliptin raised plasma GLP-1 concentrations. However, fasting (248 +/- 21 vs. 247 +/- 19 ml, P = 0.98) and fed (746 +/- 28 vs. 772 +/- 26 ml, P = 0.54) gastric volumes did not differ when subjects received vildagliptin or placebo. Treatment with vildagliptin did not alter the MTV of Ensure (1657 +/- 308 vs. 1389 +/- 197 ml, P = 0.15) or water compared to placebo (1371 +/- 141 vs. 1172 +/- 156 ml, P = 0.23). Vildagliptin was associated with decreased peptide YY (PYY) concentrations 60 min after initiation of the meal (166 +/- 27 vs. 229 +/- 34 pmol/l, P = 0.01).

CONCLUSIONS

Vildagliptin does not alter satiation or gastric volume in people with type 2 diabetes despite elevated GLP-1 concentrations. Compensatory changes in enteroendocrine secretion could account for the lack of gastrointestinal symptoms.

Gastrointestinal symptoms and glycemic control in diabetes mellitus: a longitudinal population study

BACKGROUND

The prevalence of gastrointestinal (GI) symptoms is increased in diabetes, but their natural history is understood poorly and any impact of glycemic control is controversial. We aimed to quantify changes in GI symptom status and glycemic control among a population sample of patients with diabetes.

METHODS

Data on 10 chronic GI symptom complexes were obtained from a validated questionnaire at baseline and after 12 months. Changes in acute and chronic glycemic control were classified as always adequate, variable (deteriorated or improved), or always inadequate; acute glycemic control was assessed by fasting plasma glucose and chronic glycemic control by a validated self-report 5-point graded scale.

RESULTS

Baseline and follow-up data were available in 136 individuals with diabetes (mean age 59 years; 66% males; 95% type 2). The most prevalent GI symptom complexes were abdominal bloating/distension (35%), ulcer-like dyspepsia (35%), and irritable bowel syndrome (27%). Overall, between 7 and 24% reported a change in GI symptoms with the largest change in irritable bowel syndrome (24%), bloating/distension (22%), and ulcer-like dyspepsia (21%). Those who had a change in abdominal bloating (either loss or gain) over 12 months were more likely to have increased their mean fasting plasma glucose (P<0.05). Contrary to expectations, consistently poor self-reported glycemic control was only weakly associated with less persistent abdominal pain (r=-0.2, P=0.03), diarrhea (r=-0.22, P=0.01), and abdominal bloating (r=-0.2, P=0.03). Acute glycemic control was not significantly related to any GI symptoms.

CONCLUSION

We were unable to demonstrate any association between worsening GI symptoms and glycemic control.

Small particle size of a solid meal increases gastric emptying and late postprandial glycaemic response in diabetic subjects with gastroparesis

Our goal was to investigate if food of small particle size increases the gastric emptying rate and lessens the fall in postprandial blood glucose in seven subjects with Type 1 diabetes and gastroparesis. Two solid meals of identical composition but of different particle size, with 5MBq (99m)Tc added to the meals, were ingested in randomized order in seven subjects with Type 1 Diabetes Mellitus and gastroparesis and seven healthy subjects. During 180min blood glucose and insulin concentrations were measured and gastric emptying of the ingested meals was registered by a gamma camera. The lag phase in the stomach was significantly shorter, the radioactivity remaining in the stomach after 120min (T(120)) was significant less and the postprandial blood glucose dip was less and of shorter duration after a small particle (SP) meal, compared to a large particle (LP) meal in diabetic subjects. Gastric emptying did not differ significantly between groups after an SP meal. Food of small particle size increases the gastric emptying rate and reduces the postprandial blood glucose dip in both magnitude and duration in Type 1 diabetic subjects with gastroparesis, which is likely to be of importance in achieving good metabolic control.

Upper abdominal symptoms in patients with Type 1 diabetes: unrelated to impairment in gastric emptying caused by autonomic neuropathy

AIMS

Diabetic gastroparesis is a common condition occurring in some 30-50% of patients with long-term diabetes. Some studies have found a relationship between autonomic neuropathy and diabetic gastroparesis. In addition to autonomic neuropathy, acute changes in plasma glucose concentration can also affect gastric emptying. The objective was to examine the relationship between autonomic nerve function, glucose concentration, gastric emptying, and upper abdominal symptoms in Type 1 diabetic patients.

METHODS

Gastric emptying of solids and liquids was measured with scintigraphy in 27 patients with longstanding Type 1 diabetes with upper abdominal symptoms. Autonomic nerve function was examined by standardized cardiovascular tests, and plasma glucose concentrations were measured during scintigraphy. Severity of abdominal symptoms and quality of life were explored by validated questionnaires.

RESULTS

Seven patients (26%) had delayed gastric emptying of solids and three (11%) of liquids. Mean gastric half-emptying time of solids was 128 +/- 116 min and of liquids 42 +/- 30 min. Of the 26 patients undergoing tests, 16 (62%) had autonomic nerve dysfunction. Autonomic neuropathy score (1.6 +/- 1.7) correlated positively with the gastric emptying rate of solids (P = 0.006), a rate unrelated to symptom scores or plasma glucose concentrations during scintigraphy. Quality of life in patients with abdominal symptoms was lower than in the normal Finnish population.

CONCLUSIONS

Impaired gastric emptying of solids in patients with Type 1 diabetes is related to autonomic neuropathy, but not to actual glycaemic control. The upper abdominal symptoms observed in these patients cannot be explained, however, by impaired gastric emptying.

Effect of itopride on gastric emptying in longstanding diabetes mellitus

Delayed gastric emptying (GE) occurs in 30-50% of patients with longstanding type 1 or 2 diabetes, and represents a major cause of morbidity. Current therapeutic options are limited. We aimed at evaluating the effects of itopride on GE in patients with longstanding diabetes. Twenty-five patients (20 type 1, 5 type 2; 10 males, 15 females; mean age 45.2 +/- 2.7 years; body mass index 27.5 +/- 0.9 kg m(-2); duration of diabetes 20.2 +/- 2.4 years) were enrolled in a double-blind, placebo-controlled, randomized, crossover trial. Subjects received both itopride (200 mg) and placebo t.i.d. for 7 days, with a washout of 7-14 days. GE (scintigraphy), blood glucose (glucometer) and upper gastrointestinal (GI) symptoms (questionnaire) were measured following each treatment period. The test meal comprised 100 g ground beef (99mTc-sulphur colloid) and 150 mL of 10% dextrose [67Ga-ethylenediaminetetraacetic acid (EDTA)]. There was a slight trend for itopride to accelerate both solid (P = 0.09) and liquid (P = 0.09) GE. With itopride treatment, the emptying of both solids and liquids tended to be more accelerated, as the emptying with placebo was slower (solids: r = 0.39, P = 0.057; liquids: r = 0.44, P < 0.03). Twelve (48%) patients had delayed solid and/or liquid GE on placebo and in this group, itopride modestly accelerated liquid (P < 0.05), but not solid (P = 0.39), emptying. Itopride had no effect on mean blood glucose during the GE measurement (placebo: 9.8 +/- 0.6 mmol L(-1) vs itopride: 9.6 +/-0.6 mmol L(-1)), or GI symptoms (placebo: 1.4 +/- 0.4 vs itopride: 1.8 +/- 0.5). Itopride, in a dose of 200 mg t.i.d. for 7 days, tends to accelerate GE of liquids and solids in longstanding diabetes. The magnitude of this effect appears to be modest and possibly dependent on the rate of GE without itopride.

Prevalence and determinants of delayed gastric emptying in hospitalised Type 2 diabetic patients

AIM: To determine the prevalence of delayed gastric emptying (GE) in older patients with Type 2 diabetes mellitus.

METHODS: One hundred and forty seven patients with Type 2 diabetes, of whom 140 had been hospitalised, mean age 62.3 ± 8.0 years, HbA1c 9.1% ± 1.9%, treated with either oral hypoglycemic drugs or insulin were studied. GE of a solid meal (scintigraphy), autonomic nerve function, upper gastrointestinal symptoms, acute and chronic glycemic control were evaluated. Gastric emptying results were compared to a control range of hospitalised patients who did not have diabetes.

RESULTS: Gastric emptying was delayed (T50 > 85 min) in 17.7% patients. Mean gastric emptying was slower in females (T50 72.1 ± 72.1 min vs 56.9 ± 68.1 min, P = 0.02) and in those reporting nausea (112.3 ± 67.3 vs 62.7 ± 70.0 min, P < 0.01) and early satiety (114.0 ± 135.2 vs 61.1 ± 62.6 min, P = 0.02). There was no correlation between GE with age, body weight, duration of diabetes, neuropathy, current glycemia or the total score for upper gastrointestinal symptoms.

CONCLUSION: Prolonged GE occurs in about 20% of hospitalised elderly patients with Type 2 diabetes when compared to hospitalised patients who do not have diabetes. Female gender, nausea and early satiety are associated with higher probability of delayed GE.

Consensus recommendations for gastric emptying scintigraphy: a joint report of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine

This consensus statement from the members of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine recommends a standardized method for measuring gastric emptying (GE) by scintigraphy. A low-fat, egg-white meal with imaging at 0, 1, 2, and 4 h after meal ingestion, as described by a published multicenter protocol, provides standardized information about normal and delayed GE. Adoption of this standardized protocol will resolve the lack of uniformity of testing, add reliability and credibility to the results, and improve the clinical utility of the GE test.

Therapy Insight: gastrointestinal complications of diabetes--pathophysiology and management

Patients with diabetes often have gastrointestinal symptoms, but the extent and severity of this problem and the specificity of the symptoms are not nearly as well defined as frequently assumed. Any part of the gastrointestinal tract can be affected, and the presenting symptoms depend on the composite of dysfunctional elements. Gastroesophageal reflux, Candida esophagitis, gastroparesis, diarrhea and constipation are among the many common gastrointestinal complications of diabetes. No specific risk factor for the development of these complications has been identified and their etiology is most likely to be multifactorial, involving both reversible and irreversible processes. Treatment should be directed at tighter glycemic and symptom control, which can bring about clinical improvement for many patients. For other patients, however, effective clinical management is problematic because no therapies are available to prevent or correct the underlying disease mechanisms. Studies now suggest that reduced levels of key trophic factors cause transdifferentiation of pacemaker interstitial cells of Cajal into a smooth-muscle-like phenotype. If this really is the case, therapies directed at restoring the normal milieu of trophic signals could correct the dysfunction of the interstitial cells of Cajal and resolve many gastrointestinal complications. Advances in stem cell technology also hold promise to provide a cure for diabetes and to correct abnormalities in gastrointestinal pathology.

Two-channel gastric pacing with a novel implantable gastric pacemaker accelerates glucagon-induced delayed gastric emptying in dogs

BACKGROUND

The aim of the current study was to investigate the efficacy of 2-channel gastric electrical stimulation (GES) with a custom-made implantable pacemaker on delayed gastric emptying and gastric dysrhythmia induced by glucagon in dogs.

METHODS

Six dogs were studied in 4 randomized session (saline, glucagon, glucagon with single-channel or 2-channel GES). GES was applied via the first pair of electrodes for single-channel GES or the first and third pairs of electrodes for 2-channel GES. Gastric emptying was assessed for 90 minutes and gastric slow waves were recorded at the same time.

RESULTS

Both single-channel and 2-channel GES improved gastric dysrhythmia (P < .05 vs glucagon session). Two-channel GES but not single-channel GES improved glucagon-induced delayed gastric emptying at 30 minutes, 45 minutes, 60 minutes, 75 minutes, and 90 minutes.

CONCLUSION

Two-channel GES with a novel implantable pacemaker is more efficient and effective than single-channel GES in improving delayed gastric emptying induced by glucagon. This implantable multipoint pacemaker may provide a new option for treatment of gastric motility disorders.

Glucose homeostasis and the gastrointestinal tract: insights into the treatment of diabetes

The gastrointestinal tract is increasingly viewed as a critical organ in glucose metabolism because of its role in delivering glucose to the circulation and in secreting multiple glucoregulatory hormones that, in concert with insulin and glucagon, regulate glucose homeostasis. Under normal conditions, a complex interplay of these hormones acts to maintain plasma glucose within a narrow range despite large variations in the availability of glucose, particularly during transition from the fasting to fed state. In the fed state, the rate at which nutrients are passed from the stomach to the duodenum, termed gastric emptying rate, is a key determinant of postprandial glucose flux. In patients with diabetes, the regulation of glucose metabolism is disrupted resulting in fasting and postprandial hyperglycaemia. Elucidation of the role of the gastrointestinal tract, gut-derived glucoregulatory peptides and gastric emptying rate offers a new perspective on glucose homeostasis and the respective importance of these factors in the diabetes state. This review will highlight the importance of the gastrointestinal tract in playing a key role in glucose homeostasis, particularly in the postprandial period, and the role of established or new therapies that either leverage or modify gastrointestinal function to improve glycaemic state.

Effect of apple cider vinegar on delayed gastric emptying in patients with type 1 diabetes mellitus: a pilot study

Background

Previous studies on healthy people show that vinegar delays gastric emptying and lowers postprandial blood glucose and insulin levels. The aim of this study was to investigate the effect of apple cider vinegar on delayed gastric emptying rate on diabetes mellitus patients.

Methods

Ten patients with type 1 diabetes and diabetic gastroparesis, including one patient who had undergone vagotomy, were included and completed the investigator blinded crossover trial. The gastric emptying rate (GER) was measured using standardized real-time ultrasonography. The GER was calculated as the percentage change in the antral cross-sectional area 15 and 90 minutes after ingestion of 300 g rice pudding and 200 ml water (GER1), or 300 g rice pudding and 200 ml water with 30 ml apple cider vinegar (GER2). The subjects drank 200 ml water daily before breakfast one week before the measurement of GER1. The same subjects drank 200 ml water with 30 ml vinegar daily before breakfast for two weeks before the measurement of GER2.

Results

The median values of GER1 and GER2 were 27% and 17%, respectively. The effect of vinegar on the rate of gastric emptying was statistically significant (p < 0.05).

Conclusion

This study shows that vinegar affects insulin-dependent diabetes mellitus patients with diabetic gastroparesis by reducing the gastric emptying rate even further, and this might be a disadvantage regarding to their glycaemic control.

Trial registration number

ISRCTN33841495.

Gastroparesis in type 2 diabetes mellitus: prevalence, etiology, diagnosis, and treatment

The worldwide epidemic of type 2 diabetes mellitus (T2DM) is a substantial economic and social burden. Although gastroparesis associated with type 1 diabetes mellitus (T1DM) has been recognized for years, only recently have studies shown that patients with T2DM also have high rates of gastroparesis. Individuals with T2DM constitute 90% to 95% of the diabetic population. Unique characteristics that distinguish this population are obesity, insulin resistance, and associated comorbidities. These features highlight the importance of investigating gastric emptying in individuals with T2DM and upper gastrointestinal symptoms. The purpose of this review is to examine the literature pertaining to diabetes and the effect of diabetes on gastric neuromuscular function, with a focus on T2DM. An understanding of gastric motility in T2DM is important to diagnose gastroparesis, to treat upper gastrointestinal symptoms, and to restore normal gastric motility, which may lead, in turn, to improved glucose control.

Effects of agar and pectin on gastric emptying and post-prandial glycaemic profiles in healthy human volunteers

1. Dietary fibre, such as pectin, delays gastric emptying and may enhance post-prandial glucose tolerance. Agar, which is high in fibre content, is widely used in the traditional Japanese diet. Although long-term diet therapy with agar decreases fasting plasma glucose levels in diabetes, knowledge is lacking about the acute effects of agar on gastric emptying and the post-prandial glycaemic profiles. The present study was designed to investigate the acute effects of agar. 2. Ten healthy male volunteers were studied on three occasions with three different test meals (450 kcal/500 mL): (i) a fibre-free meal; (ii) a meal with 2.0 g agar; or (iii) a meal with 5.2 g pectin. On each occasion, participants underwent a [(13)C]-acetate breath test along with serial blood sampling. To quantify gastric emptying, the half [(13)CO(2)] excretion time (t((1/2)b)) and the time for maximal [(13)CO(2)] excretion rate (t(lag)) were determined. The post-prandial glycaemic response was expressed as an incremental change from the fasting value at each sampling time. Data were analysed using repeated-measures analysis of variance (anova), followed by a post hoc paired Student's t-test with Bonferroni adjustment. 3. The time-course for respiratory [(13)CO(2)] excretion differed significantly among the three test meals (P = 0.0004, anova). Compared with the control meal, [(13)CO(2)] excretion was significantly lower following consumption of the agar meal (between 40 and 105 min post-prandially; P < 0.025, Student's t-test) and the pectin meal (between 40 and 180 min post-prandially; P < 0.025, Student's t-test). Among the three meals, significant differences were found in t((1/2)b) (P = 0.002, anova) and t(lag) (P = 0.011, anova). Compared with the control meal, the agar and pectin meals exhibited a significantly prolonged t((1/2)b) (P = 0.007 and P < 0.0001, respectively, Student's t-test) and t(lag) (P = 0.006 and P = 0.002, respectively, Student's t-test). Neither the agar nor pectin meal affected the post-prandial glucose profile. 4. In healthy adults, agar and pectin delay gastric emptying but have no impact on the post-prandial glucose response.

Gastric emptying, diabetes, and aging

Gastric emptying is mildly slowed in healthy aging, although generally remains within the normal range for young people. The significance of this is unclear, but may potentially influence the absorption of certain drugs, especially when a rapid effect is desired. Type 2 diabetes is common in the elderly, but there is little data regarding its natural history, prognosis, and management. This article focuses on the interactions between gastric emptying and diabetes, how each is influenced by the process of aging, and the implications for patient management.

The relationship between blood glucose control and intolerance to enteral feeding during critical illness

OBJECTIVE

To assess the relationship between blood glucose concentrations (BSL) and intolerance to gastric feeding in critically ill patients.

DESIGN

Prospective, case-controlled study.

PATIENTS AND PARTICIPANTS

Two-hourly BSL and insulin requirements over the first 10 days after admission were assessed in 95 consecutive feed-intolerant (NG aspirate > 250 ml during feed) critically ill patients and 50 age-matched, feed-tolerant patients who received feeds for at least 3 days. Patients with diabetes mellitus were excluded. A standard insulin protocol was used to maintain BSL at 5.0-7.9 mmol.

MEASUREMENTS AND RESULTS

The peak BSLs were significantly higher before and during enteral feeding in feed-intolerant patients. The mean and trough BSLs were, however, similar between the two groups on admission, 24 h prior to feeding and for the first 4 days of feeding. The variations in BSLs over 24 h before and during enteral feeding were significantly greater in feed-intolerant patients. A BSL greater than 10 mmol/l was more prevalent in patients with feed intolerance during enteral feeding. The time taken to develop feed intolerance was inversely related to the admission BSL (r= -0.40). The amount of insulin administered before and during enteral feeding was similar between the two groups.

CONCLUSIONS

Feed intolerance in critically ill patients is associated with a greater degree of glycaemic variation, with a greater number of patients with transient hyperglycaemia. These data suggest more intensive insulin therapy may be required to minimize feed intolerance, an issue that warrants further study.