Gastric emptying in diabetes mellitus: relationship to blood-glucose control

Medications that Regulate Gastrointestinal Transit Influence Inpatient Blood Glucose

Objective

A multitude of factors affect a hospitalized individual's blood glucose (BG), making BG difficult to predict and manage. Beyond medications well established to alter BG, such as beta-blockers, there are likely many medications with undiscovered effects on BG variability. Identification of these medications and the strength and timing of these relationships has potential to improve glycemic management and patient safety.

Materials and Methods

EHR data from 103,871 inpatient encounters over 8 years within a large, urban health system was used to extract over 500 medications, laboratory measurements, and clinical predictors of BG. Feature selection was performed using an optimized Lasso model with repeated 5-fold cross-validation on the 80% training set, followed by a linear mixed regression model to evaluate statistical significance. Significant medication predictors were then evaluated for novelty against a comprehensive adverse drug event database.

Results

We found 29 statistically significant features associated with BG; 24 were medications including 10 medications not previously documented to alter BG. The remaining five factors were Black/African American race, history of type 2 diabetes mellitus, prior BG (mean and last) and creatinine.

Discussion

The unexpected medications, including several agents involved in gastrointestinal motility, found to affect BG were supported by available studies. This study may bring to light medications to use with caution in individuals with hyper- or hypoglycemia. Further investigation of these potential candidates is needed to enhance clinical utility of these findings.

Conclusion

This study uniquely identifies medications involved in gastrointestinal transit to be predictors of BG that may not well established and recognized in clinical practice.

Pathogenesis and management of diabetic gastroparesis: An updated clinically oriented review

BACKGROUND AND AIMS

Diabetic gastroparesis (DGp) is a common and preventable complication of uncontrolled diabetes mellitus (D.M.) and significantly affects the Quality of Life of patients. Diagnosis and management present as a clinical challenge due to the disease's complexity and limited effective therapeutic options. This review aims to comprehensively outline the pathogenesis, diagnosis, and management of diabetic gastroparesis, evaluating evolving approaches to guide clinicians and provide future recommendations.

METHODS

A literature review was conducted on scholarly databases of PubMed, Google Scholar, Scopus and Web of Science encompassing published articles, gray literature and relevant clinical guidelines. Data were synthesized and analyzed to provide a comprehensive overview of diabetic gastroparesis, focusing on pathogenesis, diagnosis, and management.

RESULTS

The review intricately explores the pathogenesis contributing to diabetic gastroparesis, emphasizing autonomic neuropathy, oxidative stress, inflammation, hormonal dysregulation, microbiota alterations, and gastrointestinal neuropathy. Primary management strategies are underscored, including lifestyle modifications, symptom relief, and glycemic control. The discussion encompasses pharmacological and surgical options, highlighting the importance of a multidisciplinary approach involving various healthcare professionals for comprehensive patient care.

CONCLUSION

This review offers a thorough understanding of pathogenesis, diagnosis, and management of diabetic gastroparesis, underlining evolving approaches for clinicians. A multidisciplinary approach is crucial to address both the physical and mental health aspects of diabetes and its complications.

Constipation in DM are associated with both poor glycemic control and diabetic complications: Current status and future directions

Constipation is a major complications of diabetes mellitus. With the accelerating prevalence of diabetes worldwide and an aging population, there is considerable research interest regarding the altered function and structure of the gastrointestinal tract in diabetic patients. Despite current advances in hyperglycemic treatment strategies, the specific pathogenesis of diabetic constipation remains unknown. Patients with constipation, may be reluctant to eat regularly, which may worsen glycemic control and thus worsen symptoms associated with underlying diabetic bowel disease. This paper presents a review of the complex relationship between diabetes and constipation, exploring the morphological alterations and biomechanical remodeling associated with intestinal motility dysfunction, as well as alterations in intestinal neurons, cellular signaling pathways, and oxidative stress. Further studies focusing on new targets that may play a role in the pathogenesis of diabetic constipation may, provide new ideas for the development of novel therapies to treat or even prevent diabetic constipation.

Diabetic gastroparesis: clinical features, diagnosis and management

Diabetic gastroparesis carries a heavy burden on people with diabetes and the healthcare system. It remains underdiagnosed and represents challenges to treat. This article reviews the epidemiology, pathophysiology, clinical features, diagnosis and treatment of diabetic gastroparesis. The disorder is characterized by delayed gastric emptying without evidence of mechanical gastric outflow obstruction. It presents with upper gastrointestinal (GI) symptoms such as nausea, vomiting, early satiety, postprandial fullness, upper abdominal discomfort and or bloating. As the prevalence of diabetes has been growing over the last few decades, we would expect an increased incidence of delayed gastric emptying in poorly controlled diabetes and perhaps in line with the increasing use of medications that act on the GI tract such as incretin-based therapy. The disease results from multiple reversible and irreversible mechanisms. Diagnosing diabetic gastroparesis requires careful history, examination and investigations to exclude other disorders that could mimic its clinical presentation. Treatment involves a wide variety of options starting with optimization of glycaemic control, stopping any offending medications and lifestyle modifications followed by the introduction of medical therapeutics such as prokinetics. Then, surgical interventions are considered in refractory cases.

Dietary Interventions for Gastroparesis: A Systematic Review

Gastroparesis (Gp) is a delay in gastric emptying in the absence of a mechanical obstruction and has the capacity to cause symptoms that significantly impact a patient's quality of life. Dietary interventions are the first-line treatment in Gp, but the efficacy of different diets is unclear. This systematic review seeks to determine the effectiveness of dietary interventions on clinical outcomes in Gp. A literature search of MEDLINE Ovid from 1 March 2008 to 1 October 2021 was conducted to identify randomized controlled trials, cohort studies, and cross-sectional studies that reported dietary interventions in Gp. From the initial search, 2789 studies resulted. These were assessed by 2 independent reviewers and selected based on the primary outcomes of interest: changes in symptom-specific patient-reported outcomes and changes in gastric emptying time. A third reviewer resolved any discrepancies. Six adult studies (185 subjects) met the inclusion criteria, whereas no pediatric study did. Five of the included studies were randomized controlled trials and one was an observational study. The systematic review suggested low-fat diets, small-particle diets, diets with isoflavones, and foods considered bland, starchy, sweet, and salty did not exacerbate Gp symptoms. Small-particle diets and diets with isoflavones were found to improve gastric emptying time in patients. Additionally, small-particle diets were shown to reduce anxiety in comparison to large-particle diets. Of the randomized controlled trials, 80% were low risk of bias and 20% were fair risk of bias. The observational study was considered fair quality. The data presented in this review suggest specific dietary interventions could potentially improve Gp symptoms and gastric emptying in adult patients, particularly low-fat and small-particle diets. For pediatric Gp, data are lacking. The limited data available highlights a critical gap in the literature.

Inhibition of GSK-3β restores delayed gastric emptying in obesity-induced diabetic female mice

Diabetic gastroparesis (DG) is a clinical syndrome characterized by delayed gastric emptying (DGE). Loss of nuclear factor erythroid 2-related factor 2 (Nrf2) is associated with reduced neuronal nitric oxide synthase-α (nNOSα)-mediated gastric motility and DGE. Previous studies have shown that nuclear exclusion and inactivation of Nrf2 is partly regulated by glycogen synthase kinase 3β (GSK-3β). In the current study, the molecular signaling of GSK-3β-mediated Nrf2 activation and its mechanistic role on DG were investigated in high-fat diet (HFD)-induced obese/Type 2 diabetes (T2D) female mice. Adult female C57BL/6J mice were fed with HFD or normal diet (ND) with or without GSK-3β inhibitor (SB 216763, 10 mg/kg body wt ip) start from the 14th wk and continued feeding mice for an additional 3-wk time period. Our results show that treatment with GSK-3β inhibitor SB attenuated DGE in obese/T2D mice. Treatment with SB restored impaired gastric 1) Nrf2 and phase II antioxidant enzymes through PI3K/ERK/AKT-mediated pathway, 2) tetrahydrobiopterin (BH₄, cofactor of nNOS) biosynthesis enzyme dihydrofolate reductase, and 3) nNOSα dimerization in obese/T2 diabetic female mice. SB treatment normalized caspase 3 activity and downstream GSK-3β signaling in the gastric tissues of the obese/T2 diabetic female mice. In addition, GSK-3β inhibitor restored impaired nitrergic relaxation in hyperglycemic conditions. Finally, SB treatment reduced GSK3 marker, pTau in adult primary enteric neuronal cells. These findings emphasize the importance of GSK-3β on regulating gastric Nrf2 and nitrergic mediated gastric emptying in obese/diabetic rodents.NEW & NOTEWORTHY Inhibition of glycogen synthase kinase 3β (GSK-3β) with SB 216763 attenuates delayed gastric emptying through gastric nuclear factor erythroid 2-related factor 2 (Nrf2)-phase II enzymes in high-fat diet-fed female mice. SB 216763 restored impaired gastric PI3K/AKT/ β-catenin/caspase 3 expression. Inhibition of GSK-3β normalized gastric dihydrofolate reductase, neuronal nitric oxide synthase-α expression, dimerization and nitrergic relaxation. SB 216763 normalized both serum estrogen and nitrate levels in female obese/Type 2 diabetes mice. SB 216763 reduced downstream signaling of GSK-3β in enteric neuronal cells in vitro.

Role of sex hormones and their receptors on gastric Nrf2 and neuronal nitric oxide synthase function in an experimental hyperglycemia model

BACKGROUND

Gastroparesis, a condition of abnormal gastric emptying, is most commonly observed in diabetic women. To date, the role of ovarian hormones and/or gastric hormone receptors on regulating nitrergic-mediated gastric motility remains inconclusive.

AIM

The purpose of this study is to investigate whether sex hormones/their receptors can attenuate altered Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), neuronal Nitric Oxide Synthase (nNOS) expression and nitrergic relaxation in gastric neuromuscular tissues exposed to in-vitro hyperglycemia (HG).

METHODS

Gastric neuromuscular sections from adult female C57BL/6 J mice were incubated in normoglycemic (NG, 5 mM) or hyperglycemic (30 mM or 50 mM) conditions in the presence or absence of selective estrogen receptor (ER) agonists (ERα /PPT or ERβ: DPN); or non-selective sex hormone receptor antagonists (ER/ICI 182,780, or progesterone receptor (PR)/ RU486) for 48 h. mRNA, protein expression and nitrergic relaxation of circular gastric neuromuscular strips were assessed.

RESULTS

Our findings in HG, compared to NG, demonstrate a significant reduction in ER, Nrf2, and nNOS expression in gastric specimens. In addition, in-vitro treatment with sex hormones and/or their agonists significantly (*p < 0.05) restored Nrf2/nNOSα expression and total nitrite production. Conversely, ER, but not PR, antagonist significantly reduced Nrf2/nNOSα expression and nitrergic relaxation.

CONCLUSIONS

Our data suggest that ER's can regulate nitrergic function by improving Nrf2/nNOS expression in experimental hyperglycemia.

Supplementation of 17β-Estradiol Normalizes Rapid Gastric Emptying by Restoring Impaired Nrf2 and nNOS Function in Obesity-Induced Diabetic Ovariectomized Mice

Gastroparesis (Gp) is a multifactorial condition commonly observed in females and is characterized by delayed or rapid gastric emptying (GE). The role of ovarian hormones on GE in the pathogenesis of obesity induced type 2 diabetes mellitus (T2DM) is completely unknown. The aims of our study are to investigate whether supplementation of 17β-estradiol (E2) or progesterone (P4) restores impaired nuclear factor erythroid 2-related factor 2 (Nrf2, an oxidative stress-responsive transcription factor) and nitric oxide (NO)-mediated gastric motility in ovariectomized (OVX) mice consuming a high-fat diet (HFD, a model of T2DM). Groups of OVX+HFD mice were administered daily subcutaneous doses of either E2 or P4 for 12 weeks. The effects of E2 and P4 on body weight, metabolic homeostasis, solid GE, gastric antrum NO-mediated relaxation, total nitrite levels, neuronal nitric oxide synthase (nNOSα), and its cofactor expression levels were assessed in OVX+HFD mice. HFD exacerbated hyperglycemia and insulinemia while accelerating GE (p < 0.05) in OVX mice. Exogenous E2, but not P4, attenuated rapid gastric emptying and restored gastric nitrergic relaxation, total nitrite levels, nNOSα, and cofactor expression via normalizing Nrf2-Phase II enzymes, inflammatory response, and mitogen-activated protein kinase (MAPK) protein expression in OVX+HFD mice. We conclude that E2 is beneficial in normalizing metabolic homeostasis and gastric emptying in obese, diabetic OVX mice consuming a fat-rich diet.

Delayed Gastric Emptying Associates With Diabetic Complications in Diabetic Patients With Symptoms of Gastroparesis

OBJECTIVES

Diabetic gastroparesis (Gp) occurs more often in type 1 diabetes mellitus (T1DM) than in type 2 diabetes mellitus (T2DM). Other diabetic end-organ complications include peripheral neuropathy, nephropathy, and retinopathy (together termed triopathy). This study determines the prevalence of diabetic complications (retinopathy, nephropathy, and peripheral neuropathy) in diabetic patients with symptoms of Gp, assessing the differences between T1DM and T2DM and delayed and normal gastric emptying (GE).

METHODS

Diabetic patients with symptoms of Gp underwent history and physical examination, GE scintigraphy, electrogastrography with water load, autonomic function testing, and questionnaires assessing symptoms and peripheral neuropathy.

RESULTS

One hundred thirty-three diabetic patients with symptoms of Gp were studied: 59 with T1DM and 74 with T2DM and 103 with delayed GE and 30 without delayed GE. The presence of retinopathy (37% vs 24%; P = 0.13), nephropathy (19% vs 11%; P = 0.22), and peripheral neuropathy (53% vs 39%; P = 0.16) was not significantly higher in T1DM than in T2DM; however, triopathies (all 3 complications together) were seen in 10% of T1DM and 3% of T2DM (P = 0.04). Diabetic patients with delayed GE had increased prevalence of retinopathy (36% vs 10%; P = 0.006) and number of diabetic complications (1.0 vs 0.5; P = 0.009); however, 39% of diabetic patients with delayed GE did not have any diabetic complications.

DISCUSSION

In diabetic patients with symptoms of Gp, delayed GE was associated with the presence of retinopathy and the total number of diabetic complications. Only 10% of patients with T1DM and 3% of those with T2DM had triopathy of complications, and 39% of diabetic patients with Gp did not have any diabetic complications. Thus, the presence of diabetic complications should raise awareness for Gp in either T1DM or T2DM; however, diabetic Gp frequently occurs without other diabetic complications.

Diabetic Gastroparesis and Nondiabetic Gastroparesis

Gastroparesis can be divided into diabetic and nondiabetic, and the 3 main causes of gastroparesis are diabetic, postsurgical, and idiopathic. Delayed gastric emptying is the main manifestation of motility disorders for gastroparesis. Symptoms of gastroparesis are nonspecific and severity can vary. Nausea and vomiting are more common in diabetic gastroparesis whereas abdominal pain and early satiety are more frequent in idiopathic gastroparesis. Medication is still the mainstay of treatment of gastroparesis; however, the development of gastric electric stimulation and gastric peroral endoscopic pyloromyotomy brings more options for the treatment of diabetic and nondiabetic gastroparesis.

CCR2 upregulation in DRG neurons plays a crucial role in gastric hyperalgesia associated with diabetic gastropathy

Background

Diabetic gastropathy is a complex neuromuscular dysfunction of the stomach that commonly occurs in diabetes mellitus. Diabetic patients often present with upper gastrointestinal symptoms, such as epigastric discomfort or pain. The aim of this study was to assess gastric sensation in streptozocin-induced diabetes mellitus (DM) rats and to determine the contribution of C-C motif chemokine receptor 2 (CCR2) signaling to gastric hyperalgesia.

Results

DM rats showed signs of neuropathy (cutaneous mechanical hyperalgesia) from two weeks after streptozocin administration until the end of the experiment. Accelerated solid gastric emptying was observed at two weeks after streptozocin administration compared to the controls. Intense gastric hyperalgesia also developed in DM rats at two weeks after streptozocin administration, which was significantly reduced after intrathecal administration of the CCR2 antagonist INCB3344. Immunochemical analysis indicated that CCR2 expression was substantially upregulated in small and medium-sized dorsal root ganglia neurons of DM rats, although the protein level of monocyte chemoattractant protein-1, the preferred ligand for CCR2, was not significantly different between the control and DM groups.

Conclusions

These data suggest that CCR2 activation in nociceptive dorsal root ganglia neurons plays a role in the pathogenesis of gastric hyperalgesia associated with diabetic gastropathy and that CCR2 antagonist may be a promising treatment for therapeutic intervention.

Feasibility of intraperitoneal placental-derived mesenchymal stem cell injection in stomachs of diabetic mice

BACKGROUND AND AIM

Diabetic gastropathy is associated with loss of interstitial cells of Cajal and autonomic neuropathy. Effective management for diabetic gastropathy is still unavailable. This study was aimed to confirm the pathogenetic changes in diabetic gastropathy and to examine the effect of treatment with placental-derived mesenchymal stem cells (PDMSCs) in stomachs of animal models.

METHODS

Fourteen non-obese diabetic/ShiLtJ mice of 8 weeks were bled until week 30. Diabetes mellitus developed in 10 out of 14 mice, which all survived with insulin. The mice were grouped into three groups: nondiabetic group (n = 4), diabetic sham group (n = 5), and diabetic PDMSC group (n = 5) all of which were treated with intraperitoneal PDMSCs injection at week 30. All mice were killed at week 34, and the stomachs were examined by immunohistochemical stain with c-kit and neuronal nitric oxide synthase antibodies.

RESULTS

The number of c-kit positive cells in stomach decreased significantly in the diabetic sham group compared with that in the nondiabetic group (21.2 ± 6.7 vs 88.0 ± 29.3, P = 0.006) but increased with PDMSC treatment (21.2 ± 6.7 vs 64.0 ± 15.1, P = 0.02). The positive rate of neuronal nitric oxide synthase in neural plexus was also significantly lower in the diabetic sham group than in the nondiabetic group (22.3% ± 18.5% vs 48.0% ± 22.7%, P = 0.003) but increased with PDMSC treatment (22.3% ± 18.5% vs 43.3% ± 20.5%, P = 0.03).

CONCLUSIONS

Interstitial cells of Cajal and neural plexus decreased in stomachs of mice with diabetes mellitus but were significantly repaired with intraperitoneal injection of PDMSC.

Gastric Feeding as an Extension of an Established Enteral Nutrition Protocol

BACKGROUND

Indiscriminate gastric feeding in ICU patients imposes unacceptable risks of aspiration. Believing that a subset of ICU patients can be fed safely via the stomach, we have developed a protocol to identify appropriate patients and guide the bedside clinician in how to safely and effectively feed via the stomach.

METHODS

A literature search was done to identify appropriate medical literature. High grade evidence along with local expert opinions were used to develop a protocol. This protocol has been refined and implemented.

RESULTS

Based on perceived risk of aspiration, patients are assigned enteral access (ie, stomach vs. distal post-pyloric). Enteral formula is selected based on patient characteristics. It is then advanced by a standard protocol with specific precautions while monitoring for symptoms of intolerance. Management of intolerance is dictated by the type and severity of intolerance.

CONCLUSION

We have implemented a gastric feeding into a subset of our ICU patients. Gastric feeding requires certain precautions but appears to be safe. With more experience and better understanding of the pathogenesis gastroparesis, we believe that most ICU patients should be able to safely feed into the stomach. This is logistically easier than post-pyloric feeding and offers physiologic advantages.

Effect of dietary fat and food consistency on gastroparesis symptoms in patients with gastroparesis

BACKGROUND

Nutrition therapy for gastroparesis focuses on reducing meal size, fiber, fat intake, and increasing liquids intake relative to solid foods. Evidence to support these dietary interventions has been anecdotal. The aim of this study was to determine the effect of fat intake and solid/liquid meal consistency on symptoms in gastroparesis.

METHODS

Twelve patients with gastroparesis were studied on four separate days receiving one of four meals each day in a randomized order: high-fat solid, high-fat liquid, low-fat liquid, and low-fat solid meal. At each visit, eight gastrointestinal symptoms were rated from 0 (none) to 4 (very severe) every 15 min, before and for 4 h after meal ingestion.

KEY RESULTS

There was an increase in the total symptom score in the following order: high-fat solid > low-fat solid > high-fat liquid > low-fat liquid. For the high-fat solid meal, symptoms remained elevated throughout the 4 h postprandial period. Severity of nausea more than doubled after the high-fat solid meal, whereas the low-fat liquid meal caused the least increase in nausea.

CONCLUSIONS & INFERENCES

A high-fat solid meal significantly increased overall symptoms among individuals with gastroparesis, whereas a low-fat liquid meal had the least effect. With respect to nausea, low-fat meals were better tolerated than high-fat meals, and liquid meals were better tolerated than solid meals. These data provide support for recommendations that low-fat and increased liquid content meals are best tolerated in patients with symptomatic gastroparesis.

Diabetic gastrointestinal motility disorders and the role of enteric nervous system: current status and future directions

BACKGROUND

Gastrointestinal manifestations of diabetes are common and a source of significant discomfort and disability. Diabetes affects almost every part of gastrointestinal tract from the esophagus to the rectum and causes a variety of symptoms including heartburn, nausea, vomiting, abdominal pain, diarrhea and constipation. Understanding the underlying mechanisms of diabetic gastroenteropathy is important to guide development of therapies for this common problem. Over recent years, the data regarding the pathophysiology of diabetic gastroenteropathy is expanding. In addition to autonomic neuropathy causing gastrointestinal disturbances the role of enteric nervous system is becoming more evident.

PURPOSE

In this review, we summarize the reported alterations in enteric nervous system including enteric neurons, interstitial cells of Cajal and neurotransmission in diabetic animal models and patients. We also review the possible underlying mechanisms of these alterations, with focus on oxidative stress, growth factors and diabetes induced changes in gastrointestinal smooth muscle. Finally, we will discuss recent advances and potential areas for future research related to diabetes and the ENS such as gut microbiota, micro-RNAs and changes in the microvasculature and endothelial dysfunction.

Diabetic gastroparesis: functional/morphologic background, diagnosis, and treatment options

The regulation of gastrointestinal motility mainly involves the smooth muscle, neural (extrinsic and intrinsic), and hormonal elements, the glial cells, and the interstitial cells of Cajal. An orchestrated function of all these components is required for the appropriate propulsive movement of the food in the gastrointestinal tract. Gastroparesis, a pathological slowing-down of gastric emptying, is a result of the damage to the tissue elements involved in the regulation of motility. Gastroparesis is one of the well-known complications of long-standing diabetes mellitus. Although it is rarely a life-threatening complication, it has a deteriorating effect on the quality of life, leads to unpredictable oscillation of the blood glucose level, and increases the time required for the absorption of food and medicines. This review describes the clinical characteristics of diabetic gastroparesis and summarizes the organic and functional motility abnormalities caused by this complication. Finally, the currently available and potential future therapeutic approaches are summarized.

Gastrointestinal peptides, gastrointestinal motility, and anorexia of aging in frail elderly persons

BACKGROUND

The mechanisms involved in anorexia in frail elderly people remain unclear. The objective of this study was to establish whether fasting and postprandial levels of gastrointestinal peptides, gastrointestinal motility, and hunger are modified by age and frailty.

METHODS

Three groups of subjects were studied: (a) frail elderly (>70 years) persons, (b) non-frail elderly (>70 years) persons, and (c) healthy adults (aged 25-65 years). After an overnight fast, participants ingested a 400 Kcal liquid meal and appetite, hormonal, and gastrointestinal responses were monitored during early (0-60 min) and late (60-240 min) postprandial periods.

KEY RESULTS

Frail persons showed poor nutritional status, sarcopenia, and almost absence of hunger during fasting and postprandial periods. Older persons presented higher levels of glucose and insulin during fasting, enhanced postprandial CCK release in early postprandial period and postprandial hyperglycemia and hyperinsulinemia, but similar ghrelin levels than younger adults. Ultrasound scan showed that the fasting antral area was higher and antral compliance lower in old persons. The paracetamol absorption test showed enhanced postprandial gastric emptying in the frail. Non-gallbladder contractors showed no CCK peak in younger and non-frail groups, but the same high CCK peak as contractors in the frail.

CONCLUSIONS & INFERENCES

Frailty was associated with anorexia, risk of malnutrition, and sarcopenia. Frail persons showed impaired gastric motility (larger antral area at rest, impaired antral compliance, and enhanced postprandial emptying), impaired gallbladder motility, and fasting and/or postprandial alterations in CCK, glucose, and insulin release. Further studies are needed to determine if these factors may contribute to anorexia of aging in frail persons.

Pharmacokinetics of an Oral Drug (Acetaminophen) Administered at Various Times in Relation to Subcutaneous Injection of Exenatide (Exendin-4) in Healthy Subjects

Exenatide is an incretin mimetic with potential glucoregulatory activity in type 2 diabetes. This randomized, single-blind, placebo-controlled 6-way crossover study assessed exenatide's effect on acetaminophen pharmacokinetics. Of 40 randomized healthy subjects, 39 completed the study. On the placebo day, acetaminophen (1000 mg) was ingested and placebo injected subcutaneously at 0 hours. On exenatide days, acetaminophen was ingested at -1, 0, +1, +2, and +4 hours, relative to the 10 mug exenatide injected subcutaneously at 0 hours. With exenatide injection, mean plasma acetaminophen AUC(0-12 h) values were reduced by 11% to 24% (vs placebo). Peak plasma acetaminophen concentrations were similar for the -1-hour and placebo groups and reduced by 37% to 56% at other times. The most frequent adverse events were generally mild to moderate nausea and vomiting. Exenatide treatment concurrent with or preceding acetaminophen ingestion slowed acetaminophen absorption but had minimal effect on the extent of absorption.

Gender and estradiol as major factors in the expression and dimerization of nNOSα in rats with experimental diabetic gastroparesis

BACKGROUND

The molecular mechanisms of cellular changes responsible for diabetic gastroparesis, primarily seen in middle-aged women, still remain incompletely defined. We hypothesized that a decrease in the expression, dimerization, and post-translational modification of neuronal nitric oxide synthase alpha (nNOSα) is estrogen mediated and responsible for the gender-specific prevalence of this malady.

METHODS

We induced diabetes by injecting male and female rats with streptozotocin. Male diabetic rats without gastroparesis were then injected with estrogen for 3 weeks and evaluated for gastroparesis development. Gastric tissues were analyzed for the elucidation of biochemical events associated with diabetes and gastroparetic dysfunction.

RESULTS

Although male diabetic, gastroparetic (either streptozotocin- or estrogen-induced) rats exhibited similarity in disease pathology to that of females, the molecular mechanisms of development were different. Our results indicate that slow gastric emptying in both male diabetic, gastroparetic rat groups was not associated with the level of expression of nNOSα in gastric tissues. However, nNOSα dimerization, which reflects nNOSα activation, did decline slightly in the antrum of diabetic males with estrogen-induced gastroparesis, suggesting a possible estrogen role. Females with diabetic gastroparesis, in contrast, demonstrated significantly impaired levels and dimerization of nNOSα in the antrum and pylorus. Although the precise mechanism remains unknown, nNOSα dimerization impairment in female antrum is apparently associated with reduced phosphorylation of Ser(1416) in the activation loop of nNOSα.

CONCLUSION

Taken together, these results demonstrate that gender and estrogens may be leading factors, through molecular changes involved in nitric oxide synthesis down-regulation, within the antrum and pylorus of female diabetic, gastroparetic rats.

Effect of diabetes mellitus on pharmacokinetic and pharmacodynamic properties of drugs

The effects of diabetes mellitus on the pharmacokinetics and pharmacodynamics of drugs have been well described in experimental animal models; however, only minimal data exist for humans and the current knowledge regarding the effects of diabetes on these properties remains unclear. Nevertheless, it has been observed that the pharmacokinetics and pharmacodynamics of drugs are changed in subjects with diabetes. It has been reported that diabetes may affect the pharmacokinetics of various drugs by affecting (i) absorption, due to changes in subcutaneous adipose blood flow, muscle blood flow and gastric emptying; (ii) distribution, due to non-enzymatic glycation of albumin; (iii) biotransformation, due to regulation of enzymes/transporters involved in drug biotransformation; and (iv) excretion, due to nephropathy. Previously published data also suggest that diabetes-mediated changes in the pharmacokinetics of a particular drug cannot be translated to others. Although clinical studies exploring the effect of diabetes on pharmacodynamics are still very limited, there is evidence that disease-mediated effects are not limited only to pharmacokinetics but also alter pharmacodynamics. However, for many drugs it remains unclear whether these influences reflect diabetes-mediated changes in pharmacokinetics rather than pharmacodynamics. In addition, even though diabetes-mediated pharmacokinetics and pharmacodynamics might be anticipated, it is important to study the effect on each drug and not generalize from observed data. The available data indicate that there is a significant variability in drug response in diabetic subjects. The discrepancies between individual clinical studies as well as between ex vivo and clinical studies are probably due to (i) the restricted and focused population of subjects in clinical studies; (ii) failure to consider type, severity and duration of the disease; (iii) histopathological characteristics generally being missing; and (iv) other factors such as varying medication use, dietary protein intake, age, sex and obesity. The obesity epidemic in the developed world has also inadvertently influenced the directions of pharmacological research. This review attempts to map new information gained since Gwilt published his paper in Clinical Pharmacokinetics in 1991. Although a large body of research has been conducted and significant progress has been made, we still have to conclude that the available information regarding the effect of diabetes on pharmacokinetics and pharmacodynamics remains unclear and further clinical studies are required before we can understand the clinical significance of the effect. An understanding of diabetes-mediated changes as well as of the source of the variability should lead to the improvement of the medical management and clinical outcomes in patients with this widespread disease.

"Brittleness" in diabetes: easier spoken than broken

By definition, brittle diabetes (BD) is an unstable condition. Patients with BD suffer chronically from poor metabolic control, characterized by severe instability of glycemic values with frequent and unpredictable hypoglycemic and/or diabetic ketoacidosis episodes that cannot be attributed to failure in management. Quality of life is dramatically compromised because of very frequent acute complications leading to hospital admissions and because of premature chronic complications. It remains difficult to identify all patients with BD as diagnostic criteria are still not well defined. In practice, metabolic instability is manifested most obviously by chaotic glycemic profiles, which show greater and more unpredictable variation than in "stable" patients with diabetes. It is important that patients with BD are not adequately controlled, even by closely supervised, intensive insulin regimens, including continuous subcutaneous and/or intravenous insulin infusion. Their care is often very expensive in terms of time and resources, and their lives are constantly at risk for severe metabolic derangement. Management can also be frustrating and demoralizing for everyone involved, including the patient's family as well as the diabetes care team. Adopting a team approach, involving a broad range of disciplines, is essential in treating patients with BD and helping them to achieve and maintain both normoglycemia and quality of life.

Enterra Therapy: gastric neurostimulator for gastroparesis

Gastroparesis is a chronic disorder of gastric motility characterized by delayed gastric empting in the absence of mechanical obstruction, which can lead to symptoms of nausea, vomiting, bloating, abdominal pain, postprandial fullness and weight loss. Although there are many etiologies, the primary causes are diabetes or are idiopathic. The mainstay of treatment is dietary and drug therapies. However, many patients will continue to suffer intractable symptoms despite these treatments. Gastric neurostimulation with the Enterra Therapy system has been approved for use under the Humanitarian Device Exemption by the US FDA. The device produces pulses of electrical stimulation that are delivered to the stomach continuously. One randomized clinical trial and multiple nonrandomized unblinded clinical trials and case series have documented improvement of symptoms in intractable diabetic and idiopathic gastroparesis. The purpose of this article is to introduce the Enterra Therapy gastric neurostimulator. Gastroparesis and its pathophysiology will be discussed in this clinical context to enhance the understanding of the device and its development. We will analyze the device in detail, its placement and the results of studies evaluating its efficacy.

Metoclopramide in the treatment of diabetic gastroparesis

Gastroparesis is a chronic disorder that affects a significant subset of the population. Diabetes mellitus is a risk factor for the development of gastroparesis. Currently, metoclopramide is the only US FDA-approved medication for the treatment of gastroparesis. However, the FDA recently placed a black-box warning on metoclopramide because of the risk of related side effects, including tardive dyskinesia, the incidence of which has been cited to be as high as 15% in the literature. This review will investigate the mechanisms by which metoclopramide improves the symptoms of gastroparesis and will focus on the evidence of clinical efficacy supporting metoclopramide use in gastroparesis. Finally, we seek to document the true complication risk from metoclopramide, especially tardive dyskinesia, by reviewing the available evidence in the literature. Potential strategies to mitigate the risk of complications from metoclopramide will also be discussed.

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.

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.

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.

Effect of cinnamon on postprandial blood glucose, gastric emptying, and satiety in healthy subjects

BACKGROUND

Previous studies of patients with type 2 diabetes showed that cinnamon lowers fasting serum glucose, triacylglycerol, and LDL- and total cholesterol concentrations.

OBJECTIVE

We aimed to study the effect of cinnamon on the rate of gastric emptying, the postprandial blood glucose response, and satiety in healthy subjects.

DESIGN

The gastric emptying rate (GER) was measured by using standardized real-time ultrasonography. Fourteen healthy subjects were assessed by using a crossover trial. The subjects were examined after an 8-h fast if they had normal fasting blood glucose concentrations. GER was calculated as the percentage change in the antral cross-sectional area 15-90 min after ingestion of 300 g rice pudding (GER1) or 300 g rice pudding and 6 g cinnamon (GER2).

RESULTS

The median value of GER1 was 37%, and that of GER2 was 34.5%. The addition of cinnamon to the rice pudding significantly delayed gastric emptying and lowered the postprandial glucose response (P < 0.05 for both). The reduction in the postprandial blood glucose concentration was much more noticeable and pronounced than was the lowering of the GER. The effect of cinnamon on satiety was not significant.

CONCLUSIONS

The intake of 6 g cinnamon with rice pudding reduces postprandial blood glucose and delays gastric emptying without affecting satiety. Inclusion of cinnamon in the diet lowers the postprandial glucose response, a change that is at least partially explained by a delayed GER.

The spontaneously diabetic Torii rat with gastroenteropathy

The spontaneously diabetic Torii (SDT) rat was recently recognized as a new animal model of non-obese type 2 diabetes. As the severe diabetic ocular complications seen in SDT rats already have been investigated, we examined another common diabetic complication, gastroenteropathy. Male SDT rats developed diabetes at 20 weeks and diarrhea at 28 weeks of age. Gastrointestinal motility was evaluated at 28 weeks by measuring the distance of small intestinal transit by oral administration of the non-absorbed marker, arabic gum. SDT rats exhibited greater intestinal transit distance than control SD rats (54.1+/-2.6% versus 43.0+/-1.2%). Insulin treatment of SDT rats begun at 20 weeks of age produced improved stool and reduced intestinal transit distance (41.4+/-0.3%). Morphologically, the SDT rats exhibited longer villi and heavier weight of intestine compared to control SD rats. These results suggest that the SDT rat may be a useful animal model for studies of diabetic gastroenteropathy.

Diabetes mellitus in older men

Most persons with diabetes mellitus are over the age of 60 years. Males develop diabetes more commonly than females. Older diabetics tend to have both impaired insulin release as well as insulin resistance. In older persons diabetes mellitus is associated with decreased functional status and cognitive dysfunction. In general, older persons with diabetes are inclined to be underdiagnosed and undertreated. Managing diabetes in older persons requires special considerations because of their differences in pathophysiology of diabetes and strong association with functional, cognitive impairments and comorbidities. The use of strict therapeutic diets is not recommended in older persons. Treatment of hypertension and hyperglycemia can improve outcomes in older persons. The interdisciplinary team approach is important for care of older diabetic persons.

Effect of age-related changes in gastric physiology on tolerability of medications for older people

Studies specifically examining the effect of age upon the stomach are limited and frequently uncontrolled for the high prevalence of Helicobacter pylori in this age group. Age-related changes in gastric physiology such as reduced mucosal protection, gastric blood flow and impaired repair mechanisms may all impact upon gastrointestinal adverse effects and how older people tolerate medicines. Understanding how the upper gastrointestinal tract changes with advancing age could allow interventions that lead to more appropriate prescribing for older people, potentially reduce adverse effects, increase compliance with treatment regimens, and may allow older people to take medications that they would not otherwise tolerate. This review emphasises how the stomach changes with age, and how understanding this will aid clinicians when prescribing medications with potential gastrointestinal adverse effects to older people.

Comparison between coefficient of R-R interval variation and gastric emptying in type 2 diabetes mellitus patients

BACKGROUND

Autonomic neuropathy is a common complication of diabetes mellitus (DM).

METHOD

To clarify the relationship between cardiovascular autonomic function and gastric emptying rate, we investigated the gastric emptying and coefficient of R-R interval variation (CV(RR)) of 84 type 2 diabetic patients: 28 cases without peripheral neuropathy and 56 cases with peripheral neuropathy. All patients were subjected to a gastric emptying test according to the marker method (administration of a capsule containing 20 pieces of radiopaque marker during breakfast, followed by abdominal X-ray imaging 3 and 5 h later). Patients had their CV(RR) assessed at rest and during deep breathing.

RESULTS

Gastric emptying scores were significantly correlated with CV(RR) during deep breathing and with the duration of DM, but neither age nor CV(RR) at rest in all patients. Gastric emptying scores and CV(RR) at rest and during deep breathing in patients with peripheral neuropathy were significantly deteriorated than those in patients without peripheral neuropathy. A significant correlation between gastric emptying and CV(RR) during deep breathing could be observed in the patients with peripheral neuropathy, but not in those without it.

CONCLUSIONS

These findings showed that CV(RR) during deep breathing might be a good indicator of diabetic gastropathy and that peripheral neuropathy was closely related with cardiac and gastric autonomic neuropathy in the type 2 diabetic patients.

Reduced insulin and IGF-I signaling, not hyperglycemia, underlies the diabetes-associated depletion of interstitial cells of Cajal in the murine stomach

Damage to interstitial cells of Cajal (ICC), pacemakers, and mediators of neuromuscular neurotransmission in the gastrointestinal tract contributes to the pathogenesis of diabetic gastroenteropathy in both patients and animal models. ICC depletion in diabetes may result from chronic hyperglycemia or lost/ineffective insulin signaling. Because independent control of insulin and glucose concentrations is difficult in chronic in vivo studies, we used long-term organotypic cultures to address this problem. Murine gastric muscles were cultured in normoglycemic or hyperglycemic basal media with or without insulin or IGF-I for 1-3 months, the time required for gastroparesis and ICC damage to develop in diabetic mice. ICC were assessed by c-Kit immunohistochemistry and quantitative analysis of c-kit expression. Electrical pacemaking was studied by intracellular recording of slow waves. ICC survived for at least 34 days in unsupplemented normoglycemic media, but their networks, c-kit expression, and slow waves were profoundly reduced after 68 days. These changes could be entirely prevented by insulin or IGF-I supplementation. ICC networks were completely resistant to hyperglycemia for at least 72 days. Thus, hyperglycemia is unlikely to be responsible for the diabetes-associated depletion of ICC. In contrast, maintenance of ICC requires insulin or IGF-I, which are reduced or ineffective in diabetes.

Postoperative Gastrointestinal Tract Dysfunction

Postoperative gastrointestinal (GI) tract dysfunction (PGID) is common and is associated with increased patient suffering and cost of care. The pathogenesis of PGID is complex and multifactorial. Traditional measures intended to reduce the incidence of PGID, such as the use of prokinetic drugs, nasogastric tube drainage, and the avoidance of early fluid and/or food intake, are apparently not beneficial. The administration of larger volumes of IV fluids to achieve predetermined increases in cardiac output has been shown in randomized trials to improve gut perfusion and reduce the incidence of PGID. A multimodal approach that includes limited surgical incision, regional local anesthesia, early mobilization, and enteral feeding has been associated with a dramatic reduction in postoperative complications, PGID, and length of hospital stay. However, none of these approaches has been validated in adequately powered multicenter prospective randomized controlled trials.

Effect of mosapride on glycemic control and gastric emptying in type 2 diabetes mellitus patients with gastropathy

Delay of gastric emptying is one of the factors responsible for unfavorable glycemic control. We investigated the possible effects of mosapride, a digestive tract prokinetic agent, on glycemic control in diabetic patients complicated with gastropathy. Enrolled were 36 type II diabetic patients presenting with mild digestive tract symptoms. They were given mosapride 15 mg per day for 6 months. Seventeen cases were subjected to gastric emptying test according to marker method (administration of a capsule containing 20 pieces of radiopaque marker during breakfast, followed by abdominal X-ray imaging 3 and 5 h later). In 18 cases, HbA(1C) was improved by more than 0.3% for 6 months, whereby these 18 cases were defined as the improvement group. The remaining 18 cases were defined as the non-improvement group. In the gastric emptying study, basal number of the residual markers before administration of mosapride was determined 3 and 5 h later to show 18.3+/-1.8 and 7.6+/-5.1, respectively, in the improvement group while after administration, they were reduced down to 11.2+/-5.1 and 1.4+/-2.5, respectively. In sharp contrast, the basal counterparts in the non-improvement group were 19.1+/-1.5, and 16.4+/-3.4, respectively, whereas administration failed to reduce the number of the residual markers and they remained to be as high as 19.0+/-1.4 and 11.1+/-6.4, respectively. Gastric motility in the improvement group was much more improved by mosapride administration relative to those in the non-improvement group. Mosapride might elicit improvement in the glycemic control in the patients with diabetic gastropathy.

Perspectives on diabetic retinopathy

PURPOSE

To review the evolution of the understanding of diabetic retinopathy (DR) and methods of treating DR, the present clinically relevant practice for eye disease in patients with diabetes mellitus, and trends in clinical patient care over the next 3 to 5 years.

DESIGN

Tabular review and presentation of clinical trials contributing to the understanding and treatment of DR and the author's philosophy of care for the patient with diabetes.

RESULTS

Diabetic retinopathy is a microvascular complication of diabetes mellitus that is a significant cause of new-onset blindness. The Diabetic Retinopathy Study was the first multicentered, randomized, clinical trial in ophthalmology. This study provided the scientific evidence for treatment of DR with scatter (panretinal) photocoagulation, and led to the funding of other multicentered clinical trials, including the Early Treatment Diabetic Retinopathy Study, which greatly elucidated the natural history of DR and firmly established laser photocoagulation as treatment for proliferative diabetic retinopathy (PDR) and diabetic macular edema. The Diabetes Control and Complications Trial and United Kingdom Prospective Diabetes Study established the value of intensive glycemic control in reducing the risk of onset and progression of DR and other microvascular complications of diabetes.

CONCLUSIONS

Severe vision loss and moderate vision loss from diabetes are essentially preventable with timely detection and treatments, careful long-term follow-up and comprehensive diabetes mellitus care firmly based on clinical evidence. Future treatments, as outgrowths of further understanding of the biochemical basis of the disease, will aim at curing or preventing retinal complications from diabetes.

Development and validation of the Diabetes Bowel Symptom Questionnaire

BACKGROUND

Although gastrointestinal symptoms occur frequently, there is no validated measure of gastrointestinal symptoms in patients with diabetes mellitus.

AIM

To develop the Diabetes Bowel Symptom Questionnaire.

METHODS

A questionnaire derived from previously validated symptom measures was compiled to assess all relevant gastrointestinal and diabetes items. Face and content validity were ascertained by expert review. One hundred and sixty-eight patients with diabetes mellitus completed the instrument, and reliability was evaluated by a test-re-test procedure 1 week later. Concurrent validity was evaluated by an independent physician interview (n = 33). Measures of glycaemic control (glycated haemoglobin and plasma glucose) were compared with self-reported glycaemic control on a five-point Likert scale in diabetic out-patients (n = 166).

RESULTS

The questionnaire had adequate face and content validity. There was good to excellent test-re-test reliability for the gastrointestinal and diabetes items (median kappa: 0.63 and 0.79, respectively); concurrent validity was good to excellent (median kappa: 0.47 and 0.65, respectively), except for the items assessing the severity of gastrointestinal symptoms. Both glycated haemoglobin (P < 0.0001) and plasma glucose (P = 0.005) correlated significantly with self-reported glycaemic control.

CONCLUSION

The Diabetes Bowel Symptom Questionnaire appears to be a useful measure of gastrointestinal symptoms and glycaemic control in diabetes mellitus, and should have applicability in epidemiological and clinical studies.

Role of variability in explaining ethanol pharmacokinetics: research and forensic applications

Variability in the rate and extent of absorption, distribution and elimination of ethanol has important ramifications in clinical and legal medicine. The speed of absorption of ethanol from the gut depends on time of day, drinking pattern, dosage form, concentration of ethanol in the beverage, and particularly the fed or fasting state of the individual. During the absorption phase, a concentration gradient exists between the stomach, portal vein and the peripheral venous circulation. First-pass metabolism and bioavailability are difficult to assess because of dose-, time- and flow-dependent kinetics. Ethanol is transported by the bloodstream to all parts of the body. The rate of equilibration is governed by the ratio of blood flow to tissue mass. Arterial and venous concentrations differ as a function of time after drinking. Ethanol has low solubility in lipids and does not bind to plasma proteins, so volume of distribution is closely related to the amount of water in the body, contributing to sex- and age-related differences in disposition. The bulk of ethanol ingested (95-98%) is metabolised and the remainder is excreted in breath, urine and sweat. The rate-limiting step in oxidation is conversion of ethanol into acetaldehyde by cytosolic alcohol dehydrogenase (ADH), which has a low Michaelis-Menten constant (Km) of 0.05-0.1 g/L. Moreover, this enzyme displays polymorphism, which accounts for racial and ethnic variations in pharmacokinetics. When a moderate dose is ingested, zero-order elimination operates for a large part of the blood-concentration time course, since ADH quickly becomes saturated. Another ethanol-metabolising enzyme, cytochrome P450 2E1, has a higher Km (0.5-0.8 g/L) and is also inducible, so that the clearance of ethanol is increased in heavy drinkers. Study design influences variability in blood ethanol pharmacokinetics. Oral or intravenous administration, or fed or fasted state, might require different pharmacokinetic models. Recent work supports the need for multicompartment models to describe the disposition of ethanol instead of the traditional one-compartment model with zero-order elimination. Moreover, appropriate statistical analysis is needed to isolate between- and within-subject components of variation. Samples at low blood ethanol concentrations improve the estimation of parameters and reduce variability. Variability in ethanol pharmacokinetics stems from a combination of both genetic and environmental factors, and also from the nonlinear nature of ethanol disposition, experimental design, subject selection strategy and dose dependency. More work is needed to document variability in ethanol pharmacokinetics in real-world situations.

Intravenous glucose infusion decreases intracisternal thyrotropin-releasing hormone induced vagal stimulation of gastric acid secretion in anesthetized rats

Gastroparesis is a common complication of diabetes attributed to autonomic neuropathy. This study investigated whether acute hyperglycemia influences central thyrotropin-releasing hormone (TRH), a well-established brain medullary vagal stimulus, induced gastric acid secretion in overnight fasted, urethane-anesthetized rats. Intravenous infusion of D-glucose (20%, 30% and 40%) dose dependently reduced intracisternal TRH-induced gastric acid secretion (71+/-28 micromol/90 min) by 39%, 90% and 100% respectively. Pretreatment with cholecystokinin(A) (CCK(A)) receptor antagonist devazepide (1 mg/kg) did not influence the inhibitory effect of intravenous glucose (30%). These results indicate that hyperglycemia may have a central effect to antagonize medullary TRH stimulation of vagal outflow to the stomach.

Long-term outcome after gastrectomy for intractable diabetic gastroparesis

AIMS

To examine the long-term outlook for patients with intractable vomiting from diabetic gastroparesis who underwent major gastric surgery.

METHODS

Of 18 patients with problems from vomiting referred to the King's Diabetes Centre during the years 1994-2000, seven were considered to suffer irreversible symptoms not alleviated by protracted periods of medical treatment. They were all Type 1 Caucasian diabetic women, mean age 32 years (range 28-37 years) with multiple symptoms of severe autonomic neuropathy. They underwent major gastric surgery comprising 70% gastric resection including pylorus and antrum, with a 60-cm Roux-en-Y loop of jejunum to prevent reflux gastritis.

RESULTS

The vomiting was relieved in six of the seven patients almost immediately after surgery and during review up to more than 6 years post-operatively. There have been no serious relapses, resulting in considerable improvement in quality of life. Unfortunately, three of the patients developed renal failure, two of them needing renal support treatments 2 and 3 years after successful gastrectomy. One patient died suddenly 5 months after successful surgery and one 3 months after starting dialysis.

CONCLUSIONS

Major gastric surgery can, after careful patient selection, effectively relieve distressing vomiting from severe gastroparesis and give a greatly improved quality of life to a small group of seriously disadvantaged patients where risk of subsequent renal failure is high and where life expectancy is poor.

Aging and intestinal motility: a review of factors that affect intestinal motility in the aged

Normal aging is associated with significant changes in the function of most organs and tissues. In this regard, the gastrointestinal tract is no exception. The purpose of this review is to detail the important age-related changes in motor function of the various parts of the gastrointestinal tract and to highlight some of the important motility changes that may occur, either in relation to common age-related disorders, or as a result of certain drugs commonly prescribed in the aged. A major confounding factor in the interpretation of motor phenomena throughout the gastrointestinal tract in this age group is the frequent coexistence of neurological, endocrinological and other disease states, which may be independently associated with dysmotility. Overall, current data are insufficient to implicate normal aging as a cause of dysmotility in the elderly. Normal aging is associated with various changes in gastrointestinal motility, but the clinical significance of such changes remains unclear. More important is the impact of various age-related diseases on gastrointestinal motility in the elderly: for example, long-standing diabetes mellitus may reduce gastric emptying in up to 50% of patients; depression significantly prolongs whole-gut transit time; hypothyroidism may prolong oro-caecal transit time; and chronic renal failure is associated with impaired gastric emptying. In addition, various, frequently used drugs in the elderly cause disordered gastrointestinal motility. These drugs include anticholinergics, especially antidepressants with an anticholinergic effect, opioid analgesics and calcium antagonists.

Hyperglycemia impairs antro-pyloric coordination and delays gastric emptying in conscious rats

Delayed gastric emptying has been shown in diabetes. Although it has been proposed that hyperglycemia, and not only autonomic neuropathy, contributes to the pathogenesis of delayed gastric emptying, the inhibitory mechanism of hyperglycemia on gastric emptying remains unclear. We studied the effects of hyperglycemia per se on gastric emptying and postprandial gastric motility in conscious rats. Liquid and solid gastric emptying were compared between saline-infused rats and D-glucose-infused rats. Two strain gauge transducers were implanted on the antrum and pylorus and the postprandial antro-pyloric coordination was compared between euglycemia and hyperglycemia. D-glucose infusion for 30 min increased blood glucose level from 5.4 +/- 0.5 to 13.0 +/- 1.3 mM and significantly delayed gastric emptying. Forty minutes after the feeding, contractions with low frequency (<3 cycles min(-1)) and high amplitude (>15 g) of the antrum were observed. This period reflects the emptying process of the gastric content and the coordination between the antrum and pylorus was frequently observed. D-glucose infusion significantly reduced feeding-induced antral contractions and abolished the number of episodes of antro-pyloric coordination. Sham feeding-induced gastric contractions were also significantly reduced by hyperglycemia. Postprandial antro-pyloric coordination was not observed in vagotomized rats, suggesting a mediation of vagus nerve. It is concluded that hyperglycemia impairs antral contractions and antro-pyloric coordination in rats. The inhibitory effect of hyperglycemia on gastric emptying is mediated, at least in part, via impaired vagal activity.

Gastrointestinal transit in an animal model of human diabetes type 2: relationship to gut neuroendocrine peptide contents

Gastrointestinal transit (GIT) was determined in obese diabetic mice (ob/ob, Umeå/Bom). Blood glucose level, and insulin concentration in the serum and pancreas extracts as well as neuroendocrine peptide contents were measured in several segments of the gut. GIT was significantly slower in the obese diabetic mice, but was not correlated with the blood glucose level, serum insulin, or pancreatic insulin content. GIT was correlated with duodenal secretin content and colonic vasoactive intestinal peptide (VIP) content, but not with the content of other neuroendocrine peptides in different segments investigated. The antral gastrin content in obese diabetic mice was significantly higher than in controls. The concentration of secretin in obese diabetic mice was higher than in controls. Whereas the contents of peptide YY (PYY) and somatostatin were higher in obese diabetic mice, the contents of substance P and VIP were lower. The increased content of duodenal secretin and decreased content of colonic VIP may be among the factors that cause slow GIT in obese diabetic mice. The changes in the colonic contents of PYY, VIP and somatostatin may cause low intestinal secretion and, together with slow GIT, give rise to constipation, which is a common symptom in diabetes.

Substrate oxidation and control of food intake in men after a fat-substitute meal compared with meals supplemented with an isoenergetic load of carbohydrate, long-chain triacylglycerols, or medium-chain triacylglycerols

BACKGROUND

It has been suggested that hunger may be delayed and food intake reduced under metabolic conditions that spare carbohydrate oxidation.

OBJECTIVE

Our objective was to examine the role of glucose metabolism in the control of food intake in men by using medium-chain triacylglycerols (MCTs) to spare carbohydrate oxidation.

DESIGN

In 10 male volunteers, isolated and deprived of any time cues, we studied the effects of 4 lunches on hunger ratings, the duration of satiety, the amount of food ingested at dinner, energy expenditure, substrate oxidation, and plasma variables until the time of the dinner request. One lunch was a basic 2310-kJ meal containing 40 kJ fat substitute (Sub lunch). The 3 other lunches consisted of the same basic meal supplemented with either 1200 kJ long-chain triacylglycerols (LCT lunch), 1200 kJ MCTs (MCT lunch), or 900 kJ carbohydrate plus 300 kJ LCTs (Cho lunch).

RESULTS

Energy expenditure was not significantly different after the different lunches, but carbohydrate oxidation was lower after the MCT and LCT lunches than after the Cho lunch. Fat oxidation was greater after the MCT and LCT lunches. The time of the dinner request was significantly delayed after the Cho lunch. Food intake at dinner was significantly lower after the MCT lunch than after the Sub and Cho lunches, but the dinner meal request was not delayed.

CONCLUSION

Carbohydrate may have a greater role in the duration of satiety than does fat, but MCTs may play an active role in other aspects of the control of food intake, especially in satiation at the next meal.

Gastrointestinal transit in nonobese diabetic mouse: an animal model of human diabetes type 1

Gastrointestinal transit (GI) in the nonobese diabetic (NOD) mouse, an animal model of human diabetes type 1, was examined in animals with short- (duration 1-5 days) and long-term (duration 28-35 days) diabetes. Blood glucose level, serum insulin concentration, and gut neuroendocrine peptide content were also measured. GI was significantly rapid in NOD mice with long-term diabetes (LTD), but was not correlated with blood glucose level, serum insulin concentration, or pancreatic insulin content. GI was correlated with duodenal secretin content, but not with the content of other neuroendocrine peptides in the different segments investigated. Whereas antral vasoactive intestinal peptide (VIP) content in NOD mice with LTD was significantly higher, colonic VIP was lower in NOD mice with short-term diabetes (STD). In the duodenum, whereas the concentration of secretin in NOD mice with both STD and LTD was lower, the gastrin content was higher. Duodenal somatostatin content in NOD mice with LTD was lower. In colon, the content of galanin in NOD mice with LTD was higher than in controls. The decreased content of secretin may be among the factors that cause rapid GI in NOD mice with LTD. Changes in the antral content of VIP, duodenal somatostatin, and colonic galanin in NOD mice with LTD may cause low intestinal secretion and, together with rapid GI, give rise to diarrhoea, which is a common symptom in diabetes.

Type 2 diabetes impairs splanchnic uptake of glucose but does not alter intestinal glucose absorption during enteral glucose feeding: additional evidence for a defect in hepatic glucokinase activity

We have previously reported that splanchnic glucose uptake, hepatic glycogen synthesis, and hepatic glucokinase activity are decreased in people with type 2 diabetes during intravenous glucose infusion. To determine whether these defects are also present during more physiological enteral glucose administration, we studied 11 diabetic and 14 nondiabetic volunteers using a combined organ catheterization-tracer infusion technique. Glucose was infused into the duodenum at a rate of 22 micromol. kg(-1). min(-1) while supplemental glucose was given intravenously to clamp glucose at approximately 10 mmol/l in both groups. Endogenous hormone secretion was inhibited with somatostatin, and insulin was infused to maintain plasma concentrations at approximately 300 pmol/l (i.e., twofold higher than our previous experiments). Total body glucose disappearance, splanchnic, and leg glucose extractions were markedly lower (P < 0.01) in the diabetic subjects than in the nondiabetic subjects. UDP-glucose flux, a measure of glycogen synthesis, was approximately 35% lower (P < 0.02) in the diabetic subjects than in the nondiabetic subjects. This was entirely accounted for by a decrease (P < 0.01) in the contribution of extracellular glucose because the contribution of the indirect pathway to hepatic glycogen synthesis was similar between groups. Neither endogenous and splanchnic glucose productions nor rates of appearance of the intraduodenally infused glucose in the portal vein differed between groups. In summary, both muscle and splanchnic glucose uptake are impaired in type 2 diabetes during enteral glucose administration. The defect in splanchnic glucose uptake appears to be due to decreased uptake of extracellular glucose, implying decreased glucokinase activity. Thus, abnormal hepatic and muscle (but not gut) glucose metabolism are likely to contribute to postprandial hyperglycemia in people with type 2 diabetes.

Psychological distress is linked to gastrointestinal symptoms in diabetes mellitus

OBJECTIVE

Gastrointestinal (GI) symptoms are common in patients with long-standing diabetes mellitus, but the pathogenesis is controversial. We aimed to determine if GI symptoms are linked to psychological distress in diabetes.

METHODS

A consecutive sample of outpatients with diabetes mellitus (n = 209) and a random sample of community diabetics (n = 892) completed a validated questionnaire measuring GI symptoms, the Hospital Anxiety and Depression (HAD) Scale for anxiety and depression, and the Eysenck short neuroticism scale.

RESULTS

Overall, 42% reported one or more GI symptoms: bloating, abdominal pain, loose stools, and urgency were most common. The mean HAD and neuroticism scores were significantly higher for most GI symptoms (11 of 14, all p < 0.05), and a dose-response relationship was observed. GI symptoms were, in general, approximately twice as frequent in cases with anxiety or depression (HAD > or = 11). Anxiety, depression, and neuroticism were each independently associated with the number of GI symptoms, adjusting for age, gender, duration and type of diabetes, and self-reported glycemic control.

CONCLUSIONS

Increased levels of state anxiety and depression and neuroticism are associated with upper and lower GI symptoms in diabetes mellitus. It is uncertain whether psychological distress is causally linked to symptoms, or whether GI symptoms per se increase levels of anxiety and depression.