Fasting and post prandial pancreatic and enteroendocrine hormone levels in obese and non-obese participants.

Circulating insulin levels are known to be increased in people with higher body mass index (BMI) due to effects of adiposity on insulin resistance, whilst gut hormones have a more complex relationship, with fasting peptideYY (PYY) reported to be inversely related to BMI. This study aimed to further explore fasting and post prandial pancreatic and gut hormone concentrations in plasma samples from obese and non-obese participants. Participants with healthy BMI (n=15), overweight BMI (n=29) and obesity (n=161) had samples taken fasting and 30 min post mixed liquid meal for analysis of glucagon-like peptide-1 (GLP-1), PYY, glucose-dependent insulinotropic polypeptide (GIP), insulin and glucagon. Data visualiation used linear discriminant analysis for dimensionality reduction, to visualise the data and assess scaling of each hormone. Fasting levels of insulin, GIP and PYY were shown to be key classifiers between the 3 groups on ANCOVA analysis, with an observation of increased GIP levels in overweight, but not obese participants. In non-obese subjects, fasting GIP, PYY and insulin correlated with BMI, whereas in subjects with obesity only the pancreatic hormones glucagon and insulin correlated with BMI. Concentrations of total GLP-1 in the fasting state correlated strongly with glucagon levels, highlighting potential assay cross-reactivities. The study, which included a relatively large number of subjects with severe obesity, supported previous evidence of BMI correlating negatively with fasting PYY and positively with fasting insulin. The observation of increased fasting GIP levels in overweight but not obese participants deserves further validation and mechanistic investigation.

Pregnancy glucagon-like peptide 1 predicts insulin but not glucose concentrations.

AIMS: Incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) cause increased insulin secretion in non-pregnant adults, but their role in pregnancy, where there are additional metabolically-active hormones from the placenta, is less clear. The aim of the present study was to assess if fasting and post-load incretin concentrations were predictive of pregnancy insulin and glucose concentrations. METHODS: Pregnant women (n = 394) with one or more risk factors for gestational diabetes were recruited at 28 weeks for a 75 g oral glucose tolerance test (OGTT). Glucose, insulin, GLP-1 and GIP were measured in the fasting state and 120 min after glucose ingestion. RESULTS: Fasting plasma GLP-1 concentrations were associated with plasma insulin (standardised ß' 0.393 (0.289-0.498), p = 1.3 × 10-12; n = 306), but not with glucose concentrations (p = 0.3). The association with insulin was still evident when adjusting for BMI (ß' 0.271 (0.180-0.362), p = 1.1 × 10-8; n = 297). Likewise, at 120 min the OGTT GLP-1 concentrations were associated with plasma insulin concentrations (ß' 0.216 (0.100-0.331), p = 2.7 × 10-4; n = 306) even after adjusting for BMI (ß' 0.178 (0.061-0.294), p = 2.9 × 10-3; n = 296), but not with glucose (p = 0.9). GIP concentrations were not associated with insulin or glucose concentrations at either time point (all p > 0.2). In pregnancy plasma GLP-1, but not GIP, concentrations appear to be predictive of circulating insulin concentrations, independently of associations with BMIs. CONCLUSIONS: These results suggest that the relationship between insulin and incretins is preserved in pregnancy, but that other factors, such as placental hormones or counter-regulatory hormones, may be more important determinants of glycaemia and gestational diabetes aetiology.

LC-MS/MS based detection of circulating proinsulin derived peptides in patients with altered pancreatic beta cell function.

Routine immunoassays for insulin and C-peptide have the potential to cross-react with partially processed proinsulin products, although in healthy patients these are present at such low levels that the interference is insignificant. Elevated concentrations of proinsulin and des-31,32 proinsulin arising from pathological conditions, or injected insulin analogues, however can cause significant assay interferences, complicating interpretation. Clinical diagnosis and management therefore sometimes require methods that can distinguish true insulin and C-peptide from partially processed proinsulin or injected insulin analogues. In this scenario, the high specificity of mass spectrometric analysis offers potential benefit for patient care. A high throughput targeted LC-MS/MS method was developed as a fit for purpose investigation of insulin, insulin analogues, C-peptide and proinsulin processing intermediates in plasma samples from different patient groups. Using calibration standards and bovine insulin as an internal standard, absolute concentrations of insulin and C-peptide were quantified across a nominal human plasma postprandial range and correlated strongly with immunoassay-based measurements. The ability to distinguish between insulin, insulin analogues and proinsulin intermediates in a single extraction is an improvement over existing immunological based techniques, offering the advantage of exact identification of the species being measured. The method promises to aid in the detection of circulating peptides which have previously been overlooked but may interfere with standard insulin and C-peptide immunoassays.

"Post-GDM support would be really good for mothers": A qualitative interview study exploring how to support a healthy diet and physical activity after gestational diabetes.

BACKGROUND: Women with a history of gestational diabetes mellitus (GDM) are at high risk of developing type 2 diabetes mellitus (T2DM). They are therefore recommended to follow a healthy diet and be physically active in order to reduce that risk. However, achieving and maintaining these behaviours in the postpartum period is challenging. This study sought to explore women's views on suggested practical approaches to achieve and maintain a healthy diet and physical activity to reduce T2DM risk. METHODS: Semi-structured interviews with 20 participants in Cambridgeshire, UK were conducted at three to 48 months after GDM. The participants' current diet and physical activity, intentions for any changes, and views on potential interventions to help manage T2DM risk through these behaviours were discussed. Framework analysis was used to analyse the transcripts. The interview schedule, suggested interventions, and thematic framework were based on a recent systematic review. RESULTS: Most of the participants wanted to eat more healthily and be more active. A third of the participants considered that postpartum support for these behaviours would be transformative, a third thought it would be beneficial, and a third did not want additional support. The majority agreed that more information about the impact of diet and physical activity on diabetes risk, support to exercise with others, and advice about eating healthily, exercising with a busy schedule, monitoring progress and sustaining changes would facilitate a healthy diet and physical activity. Four other suggested interventions received mixed responses. It would be acceptable for this support to be delivered throughout pregnancy and postpartum through a range of formats. Clinicians were seen to have important roles in giving or signposting to support. CONCLUSIONS: Many women would appreciate more support to reduce their T2DM risk after GDM and believe that a variety of interventions to integrate changes into their daily lives would help them to sustain healthier lifestyles.

'Oh, I've got an appointment': A qualitative interview study exploring how to support attendance at diabetes screening after gestational diabetes.

AIMS: To explore the views of women with a history of gestational diabetes mellitus (GDM) on suggested practical approaches to support diabetes screening attendance after GDM, which is recommended but poorly attended. METHODS: We conducted semi-structured interviews with 20 participants in Cambridgeshire, UK who had been diagnosed with GDM and were 3-48 months postpartum. Interviews covered whether participants had been screened and why, plans for future screening and their views on potential interventions to facilitate attendance (at the first postpartum test and annual testing). Framework analysis was used to analyse the transcripts. The interview schedule, suggested interventions and thematic framework were based on a recent systematic review. RESULTS: Sixteen participants had undergone screening since pregnancy, explaining that they had an appointment arranged and wanted reassurance that they did not have diabetes. The participants who had not been tested were not aware that it was recommended. Only 13 had planned to attend subsequent tests at the start of the interview. Eight themes to support future attendance were discussed. The majority of the participants agreed that changing the processes for arranging tests, offering choice in test location and combining appointments would facilitate attendance. Child-friendly clinics, more opportunities to understand GDM and the role of postpartum testing, stopping self-testing and increasing their GP's awareness of their pregnancy received inconsistent feedback. The nature of the test used did not appear to influence attendance. CONCLUSIONS: The participants wanted to be screened for diabetes after GDM. We have identified interventions that could be relatively simply incorporated into routine practice to facilitate screening attendance, such as flexibility in the appointment location or time and sending invitations for tests.

Don't seek, don't find: The diagnostic challenge of Wernicke's encephalopathy.

Wernicke's encephalopathy is caused by thiamine deficiency and has a range of presenting features, including gait disturbance, altered cognitive state, nystagmus and other eye movement disorders. In the past, Wernicke's encephalopathy was described almost exclusively in the alcohol-dependent population. However, in current times, Wernicke's encephalopathy is also well recognized in many other patient groups, including patients following bariatric surgery, gastrointestinal surgery, cancer and pancreatitis. Early recognition of Wernicke's encephalopathy is vital, as prompt treatment can restore cognitive or ocular function and can prevent permanent disability. Unfortunately, Wernicke's encephalopathy is often undiagnosed - presumably because it is relatively uncommon and has a variable clinical presentation. Clinical biochemists have a unique role in advising clinicians about potential nutritional or metabolic causes of unexplained neurological symptoms and to prompt consideration of thiamine deficiency as a potential cause in high-risk patient groups. The aim of this review is to summarize the clinical features, diagnosis and treatment of Wernicke's encephalopathy and to highlight some non-traditional causes, such as after bariatric surgery.

Expected values for gastrointestinal and pancreatic hormone concentrations in healthy volunteers in the fasting and postprandial state.

BACKGROUND: Gastrointestinal hormones regulate intestinal transit, control digestion, influence appetite and promote satiety. Altered production or action of gut hormones, including glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and peptide YY (PYY), may contribute to the biological basis of obesity and altered glucose homeostasis. However, challenges in analytical methodology and lack of clarity on expected values for healthy individuals have limited progress in this field. The aim of this study was to describe expected concentrations of gastrointestinal and pancreatic hormones in healthy volunteers following a standardized meal test (SMT) or 75 g oral glucose tolerance test (OGTT). METHODS: A total of 28 healthy volunteers (12 men, 16 women; mean age 31.3 years; mean body mass index 24.9 kg/m2) were recruited to attend a hospital clinic on two occasions. Volunteers had blood sampling in the fasting state and were given, in randomized order, an oral glucose tolerance test (OGTT) and standardized mixed liquid meal test with venepuncture at timed intervals for 4 h after ingestion. Analytical methods for gut and pancreatic hormones were assessed and optimized. Concentrations of gut and pancreatic hormones were measured and used to compile ranges of expected values. RESULTS: Ranges of expected values were created for glucose, insulin, glucagon, GLP-1, GIP, PYY and free fatty acids in response to a standardized mixed liquid meal or OGTT. Intact proinsulin and C-peptide levels were also measured following the OGTT. CONCLUSIONS: These ranges of expected values can now be used to compare gut hormone concentrations between healthy individuals and patient groups.

Peptidomic analysis of endogenous plasma peptides from patients with pancreatic neuroendocrine tumours.

RATIONALE: Diagnosis of pancreatic neuroendocrine tumours requires the study of patient plasma with multiple immunoassays, using multiple aliquots of plasma. The application of mass spectrometry based techniques could reduce the cost and amount of plasma required for diagnosis. METHODS: Plasma samples from two patients with pancreatic neuroendocrine tumours were extracted using an established acetonitrile-based plasma peptide enrichment strategy. The circulating peptidome was characterised using nano and high flow rate liquid chromatography/mass spectrometry (LC/MS) analyses. To assess the diagnostic potential of the analytical approach, a large sample batch (68 plasmas) from control subjects, and aliquots from subjects harbouring two different types of pancreatic neuroendocrine tumour (insulinoma and glucagonoma), were analysed using a 10-min LC/MS peptide screen. RESULTS: The untargeted plasma peptidomics approach identified peptides derived from the glucagon prohormone, chromogranin A, chromogranin B and other peptide hormones and proteins related to control of peptide secretion. The glucagon prohormone derived peptides that were detected were compared against putative peptides that were identified using multiple antibody pairs against glucagon peptides. Comparison of the plasma samples for relative levels of selected peptides showed clear separation between the glucagonoma and the insulinoma and control samples. CONCLUSIONS: The combination of the organic solvent extraction methodology with high flow rate analysis could potentially be used to aid diagnosis and monitor treatment of patients with functioning pancreatic neuroendocrine tumours. However, significant validation will be required before this approach can be clinically applied.

Targeted intestinal delivery of incretin secretagogues-towards new diabetes and obesity therapies.

A new strategy under development for the treatment of type 2 diabetes and obesity is to mimic some of the effects of bariatric surgery by delivering food-related stimuli to the distal gastrointestinal tract where they should enhance the release of gut hormones such as glucagon-like peptide-1 (GLP-1) and peptideYY (PYY). Methods include inhibition of food digestion and absorption in the upper GI tract, or oral delivery of stimuli in capsules or pelleted form to protect them against gastric degradation. A variety of agents have been tested in humans using capsules, microcapsules or pellets, delivering nutrients, bile acids, fatty acids and bitter compounds. This review examines the outcomes of these different approaches and supporting evidence from intestinal perfusion studies.

Natural selection? The evolution of diagnostic criteria for gestational diabetes.

Gestational diabetes is a common pregnancy disorder which is generally managed with diet, exercise, metformin or insulin treatment and which usually resolves after delivery of the infant. Identifying and treating gestational diabetes improves maternal and fetal outcomes and allows for health promotion to reduce the mother's risk of type 2 diabetes in later life. However, there remains considerable controversy about the optimal method of identification and diagnosis of women with gestational diabetes. The NICE-2015 diagnostic criteria (75 g oral glucose tolerance test (OGTT) 0 h ≥5.6 mmol/L; 2 h ≥7.8 mmol/L) are based upon cost-effectiveness estimates using observational data, while the WHO-2013 criteria (75 g OGTT 0 h ≥5.1 mmol/L; 1 h ≥10.0 mmol/L; 2 h ≥8.5 mmol/L) identify women and infants at risk of adverse outcomes according to prospective data. There is also considerable controversy about testing for gestational diabetes using universal or risk factor-based screening, and when and how testing should be performed. The aim of this review is to provide a summary of the clinical biochemistry aspects to these debates and to highlight the importance of appropriate identification of gestational diabetes and subsequent type 2 diabetes in this population.

The effect of bariatric surgery on gastrointestinal and pancreatic peptide hormones.

Bariatric surgery for obesity has proved to be an extremely effective method of promoting long-term weight reduction with additional beneficial metabolic effects, such as improved glucose tolerance and remission of type 2 diabetes. A range of bariatric procedures are in common use, including gastric banding, sleeve gastrectomy and the Roux-en-Y gastric bypass. Although the mechanisms underlying the efficacy of bariatric surgery are unclear, gastrointestinal and pancreatic peptides are thought to play an important role. The aim of this review is to summarise the effects of different bariatric surgery procedures upon gastrointestinal and pancreatic peptides, including ghrelin, gastrin, cholecystokinin (CCK), glucose-dependent insulinotropic hormone (GIP), glucagon-like peptide 1 (GLP-1), peptide YY (PYY), oxyntomodulin, insulin, glucagon and somatostatin.

The effect of encapsulated glutamine on gut peptide secretion in human volunteers.

CONTEXT: Weight loss and improved blood glucose control after bariatric surgery have been attributed in part to increased ileal nutrient delivery with enhanced release of glucagon-like peptide 1 (GLP-1). Non-surgical strategies to manage obesity are required. The aim of the current study was to assess whether encapsulated glutamine, targeted to the ileum, could increase GLP-1 secretion, improve glucose tolerance or reduce meal size. METHODS: A single-center, randomised, double blind, placebo-controlled, cross-over study was performed in 24 healthy volunteers and 8 patients with type 2 diabetes. Fasting participants received a single dose of encapsulated ileal-release glutamine (3.6 or 6.0 g) or placebo per visit with blood sampling at baseline and for 4h thereafter. Glucose tolerance and meal size were studied using a 75 g oral glucose tolerance test and ad libitum meal respectively. RESULTS: In healthy volunteers, ingestion of 6.0 g glutamine was associated with increased GLP-1 concentrations after 90 min compared with placebo (mean 10.6 pg/ml vs 6.9 pg/ml, p=0.004), increased insulin concentrations after 90 min (mean 70.9 vs 48.5, p=0.048), and increased meal size at 120 min (mean 542 g eaten vs 481 g, p=0.008). Ingestion of 6.0 g glutamine was not associated with significant differences in GLP-1, glucose or insulin concentrations after a glucose tolerance test in healthy or type 2 diabetic participants. CONCLUSIONS: Single oral dosing of encapsulated glutamine did not provoke consistent increases in GLP-1 and insulin secretion and was not associated with beneficial metabolic effects in healthy volunteers or patients with type 2 diabetes.

Biochemical consequences of bariatric surgery for extreme clinical obesity.

Obesity, defined as a body mass index over 30 kg/m(2) for adults, poses a major healthcare challenge with important economic, personal and social consequences. Although public health measures, lifestyle change and pharmacological therapies have an important role in the management of obesity, patients with established morbid obesity (body mass index over 40 kg/m(2)) may also require bariatric surgery. Bariatric or metabolic surgery is associated with effective and enduring weight loss but is also known to improve glucose homeostasis, blood pressure and dyslipidaemia. Patients who have bariatric surgery need lifelong clinical follow-up to identify and prevent nutritional deficiencies and other complications. Clinical biochemistry laboratories have an important role in the nutritional assessment of obese patients and in the identification of complications following bariatric surgery. The aim of this article is to review the different bariatric procedures available and to summarize their complications, especially nutrient deficiencies and those of particular relevance to clinical biochemistry laboratories.

Can encapsulated glutamine increase GLP-1 secretion, improve glucose tolerance, and reduce meal size in healthy volunteers? A randomised, placebo-controlled, cross-over trial.

BACKGROUND: Obesity is a global concern and can be effectively treated with bariatric surgery, which is expensive and invasive. Weight loss after surgery has been attributed to increased nutrient delivery to the lower small intestine with release of satiety-promoting gut hormones such as glucagon-like peptide 1 (GLP-1). We aimed to assess whether glutamine, a potent secretagogue of GLP-1 in vivo, increases GLP-1 release, improves glucose tolerance, or reduces meal size in volunteers. METHODS: A single-centre, randomised, double blind, placebo-controlled, cross-over study was performed in Cambridge, UK, studying the effects of a single dose of encapsulated ileal-release glutamine (6 g) and placebo (microcrystalline cellulose) in healthy adult volunteers. Volunteers were recruited for each endpoint and received each regimen in random order (performed by electronic random number generation). The primary outcome was within-person GLP-1 in venous blood (concentrations and area under the curve). Secondary outcomes were glucose tolerance (measured with an oral glucose tolerance test given after 90 min) and meal size (ad-libitum meal given at 120 min). Inclusion of 8-10 participants for each endpoint would achieve 90% power with α at 0·05. Significance testing was done with the paired t test. Participants gave written informed consent and the study was approved by the local research ethics committee. This trial is registered with the ISRCTN register, number ISRCTN10757078. FINDINGS: 11 men and 13 women were recruited (aged 22-58 years, body-mass index 18·5-31·8 kg/m(2)). Ten patients were assigned to assessment of GLP-1, eight to assessment of glucose tolerance, and ten for meal size. Some volunteers participated in more than one part of the study. Ingestion of 6 g glutamine was associated with increased GLP-1 concentrations after 90 min compared with placebo (mean 3·2 pmol/L [SD 0·86] vs 2·1 [0·65], p=0·004), increased insulin concentrations after 90 min (70·9 [37·9] vs 51·5 [23·1], p=0·048), and increased meal size at 120 min (542 g eaten [188] vs 481 [193], p=0·008). No safety concerns were identified after the ingestion of glutamine. INTERPRETATION: This trial shows that a single oral dose of encapsulated glutamine can promote increased secretion of GLP-1 and is associated with increased insulin release. However, the effect size was small and unlikely to be clinically useful. Glutamine was associated with increased meal size, an undesirable effect, perhaps because the orexigenic effects of insulin release predominated over the anorexigenic effects of GLP-1 release after administration of glutamine. FUNDING: European Union's Seventh Framework Programme, Wellcome Trust Translational Medicine & Therapeutics Programme, National Institute for Health Research.

The relationship between the insulin-like growth factor-1 axis, weight loss, an inflammation-based score and survival in patients with inoperable non-small cell lung cancer.

BACKGROUND & AIMS: The involvement of a systemic inflammatory response, as evidenced by the Glasgow Prognostic Score (GPS), is associated with weight loss and poor outcome in patients with non-small cell lung cancer. There is good evidence that nutritional and functional decline in patients with advanced malignant disease is associated with catabolic changes in metabolism. However, defects in anabolism may also contribute towards nutritional decline in patients with cancer. The aim of the present study was to examine the relationship between IGF-1 and IGFBP-3, performance status, mGPS and survival in patients with inoperable NSCLC. METHODS: 56 patients with inoperable NSCLC were studied. The plasma concentrations of IGF-1, IGFBP-3 and leptin were measured using ELISA and RIA. RESULTS: The patients were predominantly male (61%), over 60 years old (80%), with advanced (stage III or IV) disease (98%), with a BMI> or =20 (84%), an ECOG-ps of 0 or 1 (79%), a haemoglobin (59%) and white cell count (79%) in the reference range. On follow-up 43 patients died of their cancer. On univariate analysis, BMI (p<0.05), Stage (p<0.05), ECOG-ps (p<0.05), haemoglobin (p<0.05), white cell count (p<0.05) and mGPS (p<0.05) were associated with cancer specific survival. There was no association between age, sex, treatment, IGF-1, IGFBP-3, IGF-1:IGFBP-3 ratio, or leptin and cancer specific survival. With an increasing mGPS concentrations of haemoglobin (p<0.005) and IGFBP-3 (p<0.05) decreased. mGPS was not associated with either IGF-1(p>0.20), or leptin (p>0.20). CONCLUSIONS: In summary, the results of this study suggest that anabolism (IGF-1 axis) does not play a significant role in the relationship between nutritional and functional decline, systemic inflammation and poor survival in patients with inoperable NSCLC.