GLP-1 release in man after lower large bowel resection or intrarectal glucose administration

Effects of Lifestyle Interventions on Health and Life Quality of Colorectal Cancer Survivors: A Systematic Review and Meta-analysis

BACKGROUND

The results of previous studies on the effects of lifestyle interventions on the quality of life (QoL) in colorectal cancer (CRC) survivors remain controversial, and there have been several new publications in this area in recent years.

OBJECTIVES

To assess whether lifestyle interventions can lead to favorable health outcomes and improved QoL in CRC survivors, we performed a meta-analysis.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched to obtain relevant literature published from January 1, 1990, to November 1, 2021. The required data were extracted and summarized to compare the physical activity levels, QoL, mental health assessment, and anthropometric data between lifestyle interventions and routine nursing.

RESULTS

Twelve studies were included. Compared with the control group, lifestyle interventions could significantly increase the physical activity time (weighted mean difference [WMD], 9.84; 95% confidence interval [CI], 1.20-18.48; P = .026), metabolic equivalent task levels (WMD, 10.40; 95% CI, 5.30-15.49; P < .001), and Functional Assessment of Cancer Therapy Scale-Colorectal scores (WMD, 3.12; 95% CI, 0.24-5.99; P = .034). However, lifestyle interventions were not noticeably able to improve the fatigue, depression levels, anxiety levels, waist circumference, or body mass index in CRC survivors.

CONCLUSION

Lifestyle interventions could generate an increase in physical activity time, metabolic equivalent task levels, and QoL in CRC survivors.

IMPLICATIONS FOR PRACTICE

Lifestyle interventions in the future that include physical activity, diet, or comprehensive programs are needed to increase physical activity levels and improve QoL in CRC survivors.

Is Colectomy Associated with the Risk of Type 2 Diabetes in Patients without Colorectal Cancer? A Population-Based Cohort Study

Type 2 diabetes might be influenced by colonic disease; however, the association between colonic resection and type 2 diabetes has rarely been discussed. This population-based cohort study explored the association between colectomy and type 2 diabetes in patients without colorectal cancer. A total of 642 patients who underwent colectomy for noncancerous diseases at any time between 2000 and 2012 in the National Health Insurance Research Database of Taiwan were enrolled. The enrolled patients were matched with 2568 patients without colectomy at a 1:4 ratio using a propensity score that covered age, sex, and comorbidities. The risk of type 2 diabetes was assessed using a Cox proportional hazards model. The mean (standard deviation) follow-up durations in colectomy cases and non-colectomy controls were 4.9 (4.0) and 5.6 (3.6) years, respectively; 65 (10.1%) colectomy cases and 342 (15.5%) non-colectomy controls developed type 2 diabetes. After adjustment, colectomy cases still exhibited a decreased risk of type 2 diabetes (adjusted HR = 0.80, 95% CI: 0.61–1.04). A stratified analysis for colectomy type indicated that patients who underwent right or transverse colectomy had a significantly lower risk of developing type 2 diabetes (adjusted HR = 0.57, 95% CI: 0.34–0.98). In the present study, colectomy tended to be at a reduced risk of type 2 diabetes in patients without colorectal cancer, and right or transverse colectomies were especially associated with a significantly reduced risk of type 2 diabetes.

Interval Walking Improves Glycemic Control and Body Composition After Cancer Treatment: A Randomized Controlled Trial

CONTEXT

Patients with colorectal cancer have increased risk of metabolic diseases including diabetes. Exercise training may counteract metabolic dysregulation, but the impact of exercise training on glycemic control, including postprandial glycemia, has never been explored in patients with colorectal cancer.

OBJECTIVE

To examine the effects of home-based interval walking on aerobic and metabolic fitness and quality of life in patients with colorectal cancer.

DESIGN

Randomized controlled trial.

SETTING

Clinical research center.

PARTICIPANTS

Thirty-nine sedentary (<150 minutes moderate-intensity exercise per week) patients with stage I to III colorectal cancer who had completed primary treatment.

INTERVENTION

Home-based interval walking 150 min/wk or usual care for 12 weeks.

MAIN OUTCOME MEASURES

Changes from baseline to week 12 in maximum oxygen uptake (VO2peak) by cardiopulmonary exercise test, glycemic control by oral glucose tolerance test (OGTT), body composition by dual-energy x-ray absorptiometry scan, blood biochemistry, and quality of life.

RESULTS

Compared with control, interval walking had no effect on VO2peak [mean between-group difference: -0.32 mL O2 · kg-1 · min-1 (-2.09 to 1.45); P = 0.721] but significantly improved postprandial glycemic control with lower glucose OGTT area under the curve [-126 mM · min (-219 to -33); P = 0.009], 2-hour glucose concentration [-1.1 mM (-2.2 to 0.0); P = 0.056], and improved Matsuda index [1.94 (0.34; 3.54); P = 0.01]. Also, interval walking counteracted an increase in fat mass in the control group [-1.47 kg (-2.74 to -0.19); P = 0.025].

CONCLUSION

A home-based interval-walking program led to substantial improvements in postprandial glycemic control and counteracted fat gain in posttreatment patients with colorectal cancer, possibly providing an effective strategy for prevention of secondary metabolic diseases.

Mechanisms Controlling Glucose-Induced GLP-1 Secretion in Human Small Intestine

Intestinal glucose stimulates secretion of the incretin hormone glucagon-like peptide 1 (GLP-1). The mechanisms underlying this pathway have not been fully investigated in humans. In this study, we showed that a 30-min intraduodenal glucose infusion activated half of all duodenal L cells in humans. This infusion was sufficient to increase plasma GLP-1 levels. With an ex vivo model using human gut tissue specimens, we showed a dose-responsive GLP-1 secretion in the ileum at ≥200 mmol/L glucose. In ex vivo tissue from the duodenum and ileum, but not the colon, 300 mmol/L glucose potently stimulated GLP-1 release. In the ileum, this response was independent of osmotic influences and required delivery of glucose via GLUT2 and mitochondrial metabolism. The requirement of voltage-gated Na⁺ and Ca²⁺ channel activation indicates that membrane depolarization occurs. K_ATP channels do not drive this, as tolbutamide did not trigger release. The sodium-glucose cotransporter 1 (SGLT1) substrate α-MG induced secretion, and the response was blocked by the SGLT1 inhibitor phlorizin or by replacement of extracellular Na⁺ with N-methyl-d-glucamine. This is the first report of the mechanisms underlying glucose-induced GLP-1 secretion from human small intestine. Our findings demonstrate a dominant role of SGLT1 in controlling glucose-stimulated GLP-1 release in human ileal L cells.

Long-term oral administration of cows' milk improves insulin sensitivity in rats fed a high-sucrose diet

We evaluated the effects of long-term daily cows' milk (CM) administration on insulin resistance induced by a high-sucrose diet. F344 rats, aged 3 weeks, were divided into two groups according to diet (dextrin-fed v. sucrose-fed). These groups were further divided into two groups receiving either CM or artificial milk (AM; isoenergetic emulsion of egg white protein, maltose, lard and minerals). Rats were fed a sucrose- or dextrin-based diet for 7 weeks and orally administered CM or AM at 25 ml/kg following an 8 h fast on a daily basis. Insulin sensitivity was evaluated via postprandial changes in serum glucose and insulin, oral glucose tolerance tests, and fasting serum insulin and fructosamine concentrations. The sucrose-fed rats showed an overall decrease in insulin sensitivity, but postprandial insulin levels were lower in the CM-treated subgroup than in the AM-treated subgroup. Peak serum glucose and insulin concentrations were highest in the sucrose-fed rats, but CM administration reduced peak glucose and insulin values in comparison with AM administration. By area under the curve analysis, insulin levels after feeding and glucose loads were significantly lower in the CM-treated groups than in the AM-treated groups. The CM-treated groups also demonstrated lower fasting insulin and fructosamine levels than the AM-treated groups. Improved insulin sensitivity due to CM administration seemed to be associated with reduced duodenal GLUT2 mRNA levels and increased propionate production within the caecum.

Evidence for altered control of glucose disposal after total colectomy

Colonic fermentation of organic matter to short-chain fatty acids has been implicated in the improvement in insulin sensitivity achieved by feeding diets rich in complex carbohydrates. The present study assessed the potential role of the colon in determining postprandial glucose kinetics. Metabolic responses to a complex-carbohydrate test meal were determined in conjunction with a primed continuous infusion of D-[6,6-2H]glucose in a group of ileostomists and sex-matched controls. Glucose disposal (GD) was computed using non-steady-state kinetics on a single compartment model. Insulin sensitivity was derived using cumulative GD as the dependent variable, and time and the integrated insulin concentration as independent variables. The ileostomist group had a significantly higher postprandial plasma insulin concentration (P=0·034) compared with the control group, but no difference in the plasma glucose concentration. Total GD was similar in each group, although the insulin-dependent GD was substantially lower in the ileostomists (0·46 v. 0·13 mg glucose/min per pmol, P=0·015). The ileostomist group also showed a 50 % lower rate of glucose oxidation in the postprandial period (P=0·005), although the rate of non-oxidative GD was not significantly affected. The present study indicates that loss of the colon is associated with several characteristics of the insulin resistance syndrome, and favours a view that the colon has a role in the control of postprandial glucose.

Glucagon-like peptide 1 (GLP-1) and metabolic diseases

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone, mainly secreted after meals, which enhances glucose-induced insulin secretion and induces satiety. It has been reported that GLP-1 levels after a mixed meal and after an oral glucose load are reduced in patients with Type 2 diabetes. The reduction of oral glucose-stimulated active GLP-1 levels in patients with Type 2 diabetes has also been observed during euglycemic iperinsulinemic clamp. The reduction of post-prandial circulating active GLP-1 in Type 2 diabetic subjects, as a consequence of chronic hyperglycemia, could contribute to the reduction of early post-prandial insulin secretion; in fact, the administration of GLP-1 receptor antagonists to healthy volunteers elicits both an impairment of meal-induced insulin secretion and an increase of post-prandial glycemia similar to that observed in Type 2 diabetes. GLP-1 is rapidly inactivated by dipeptidyl peptidase IV (DPP-IV), an enzyme produced by endothelial cells in different districts and that circulates in plasma. It is still not clear whether the reduction of mealor oral-glucose stimulated GLP-1 levels in Type 2 diabetic patients is due to impairment of secretion, increase of degradation, or both. The major limitation of using GLP-1 to treat diabetic patients is the short half-life of the native compound. There are now several compounds in various stages of pre-clinical or clinical development for the treatment of Type 2 diabetes that utilize the GLP-1 signaling pathway; these include GLP-1 receptor agonists with extended half-lives, and inhibitors of DPP-IV that increase circulating levels of endogenous, intact and bioactive GLP-1.

The incretin effect and its potentiation by glucagon-like peptide 1-based therapies: a revolution in diabetes management

The incretin effect is a phenomenon in which enteral glucose administration provokes greater insulin secretion than intravenous administration. The main incretins, glucose-dependent insulinotropic peptide and glucagon-like peptide (GLP)-1 are defective in Type 2 diabetes; whereas glucose-dependent insulinotropic peptide displays diminished effectiveness, GLP-1 secretion is decreased; thus, GLP-1 was a stronger candidate for a new class of anti-diabetic agents designed to potentiate the incretin effect. In the past decade, GLP-1 mimetics, peptidase inhibitors and GLP-1 have been developed. Early randomised trials show that these agents contribute to glucose homeostasis and enhance beta-cell function, without causing hypoglycaemia or weight gain. This review includes an historical perspective, physiology of incretins, and discussions of the pathophysiology in Type 2 diabetes, pharmacology of the main agents and randomised clinical trials published to date.

Enhanced glucose-dependent glucagon-like peptide-1 and insulin secretion in Crohn patients with terminal ileum disease is unrelated to disease activity or ileal resection

BACKGROUND

Enhanced secretion of glucagon-like peptide-1 (GLP-1) has been reported in patients with Crohn disease (CD). However, the correlation between the enteropancreatic axis and the activity of CD remains unclear.

METHODS

Plasma glucose, insulin, GLP-1 levels and insulin sensitivity were determined before and after oral glucose tolerance tests in 13 patients with CD of the terminal ileum, in 13 patients after resection of the terminal ileum and in 7 healthy controls. Basal and stimulated insulin sensitivities were determined using the homeostasis model assessment (HOMA) and the insulin sensitivity index (ISI) methods, respectively.

RESULTS

Basal and stimulated glucose levels were comparable in patients and controls. The peak stimulated GLP-1 secretion was significantly higher in the patient group compared to controls: 12.2 +/- 1.24 pM/L and 8.1 +/- 1.72 pM/L, respectively, P=0.03. This was associated with 52% increased overall insulin secretion in the patients' group as compared to controls (P=0.007) and a higher peak insulin response: 63.5 +/- 9.69 mU/L and 41.5 +/- 6.85 mU/L for patients and controls, respectively, P=0.04. Operated patients had similar GLP-1 levels but higher peak and overall insulin secretions compared with those in non-operated patients (P=0.01). Fasting and stimulated insulin sensitivities were reduced only in patients with ileal resection as compared to controls: P=0.01 and P=0.05, respectively. No correlation was found between the CD activity index and GLP-1 or insulin secretion.

CONCLUSIONS

CD of the terminal ileum is associated with enhanced glucose-dependent GLP-1 secretion, which is unrelated to disease activity or ileal resection.

Dextrose is absorbed by rectum in hypoglycemic rats

The objective of this study was to determine the efficacy of the rectal administration of dextrose in raising the serum glucose in a hypoglycemic rat model. A randomized, prospective, controlled experimental study was performed using 18-h fasted, acutely anesthetized Harlan Sprague-Dawley rats made hypoglycemic by the intravenous infusion of insulin at 3 U/kg/h for 2 h. At 1 h into the infusion, study rats received 1, 2, or 3 g/kg of 50% dextrose solution infused into the rectum using a balloon tipped catheter. Control animals received an equivolume, equi-osmolar (as compared to the 3 g/kg dose) amount of polyethylene glycol (PEG)-400 by rectum. Blood glucose (BG) measurements were made using blood obtained from the portal vein and a femoral artery. Intravenous insulin administered at 3 U/kg/h consistently produced BG levels 60% of baseline at 60 min and 80% of baseline at 120 min. BG levels in portal and arterial circulation increased after rectal dextrose. In general, portal venous values were greater than arterial after rectal dextrose. The greatest increase was seen 30 min after dextrose by rectum in animals receiving 3 g/kg. A 50% dextrose administered by rectum in hypoglycemic rats is absorbed in quantities sufficient to raise BG in the arterial and portal circulation.