Levels of circulating semaglutide determine reductions in HbA1c and body weight in people with type 2 diabetes.

Glucagon-like peptide-1 receptor agonists (GLP-1RA) are used for the treatment of type 2 diabetes. Whether clinically important responses and adverse events (AEs) are dependent on the route of administration has not been determined. We demonstrate that nearly identical exposure-response pharmacodynamic relationships are determined by plasma semaglutide levels achieved through oral versus injectable administration for changes in HbA1c, body weight, biomarkers of cardiovascular risk, and AEs such as nausea and vomiting. At typical exposure levels for oral semaglutide, the estimated response is 1.58% (oral) versus -1.62% (subcutaneous) for HbA1c and 3.77% (oral) versus 3.48% (subcutaneous) reduction in body weight relative to baseline after 6 months. Increased body weight is the most important variable associated with reduced semaglutide exposure for both formulations. Hence, interindividual variation in GLP-1R responsivity or route of administration are not major determinants of GLP-1RA effectiveness in the clinic.

Safety and Pharmacokinetics of Single and Multiple Ascending Doses of the Novel Oral Human GLP-1 Analogue, Oral Semaglutide, in Healthy Subjects and Subjects with Type 2 Diabetes.

BACKGROUND: Oral semaglutide is a novel tablet containing the human glucagon-like peptide-1 (GLP­1) analogue semaglutide, co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). The safety and pharmacokinetics of oral semaglutide were investigated in two randomised, double-blind, placebo-controlled trials. METHODS: In a single-dose, first-in-human trial, 135 healthy males received oral semaglutide (2-20 mg semaglutide co-formulated with 150-600 mg SNAC) or placebo with SNAC. In a 10-week, once-daily, multiple-dose trial, 84 healthy males received 20 or 40 mg oral semaglutide (with 300 mg SNAC), placebo, or placebo with SNAC, and 23 males with type 2 diabetes (T2D) received 40 mg oral semaglutide (with 300 mg SNAC), placebo, or placebo with SNAC. RESULTS: Oral semaglutide was safe and well-tolerated in both trials. The majority of adverse events (AEs) were mild, with the most common AEs being gastrointestinal disorders. In the single-dose trial, semaglutide exposure was highest when co-formulated with 300 mg SNAC. In the multiple-dose trial, semaglutide exposure was approximately twofold higher with 40 versus 20 mg oral semaglutide in healthy males, in accordance with dose proportionality, and was similar between healthy males and males with T2D. The half-life of semaglutide was approximately 1 week in all groups. CONCLUSION: The safety profile of oral semaglutide was as expected for the GLP-1 receptor agonist drug class. Oral semaglutide co-formulated with 300 mg SNAC was chosen for further clinical development. The pharmacokinetic results supported that oral semaglutide is suitable for once-daily dosing. CLINICALTRIALS. GOV IDENTIFIERS: NCT01037582, NCT01686945.

On the role of the gut in diabetic hyperglucagonaemia.

Patients with type 2 diabetes are characterised not only by compromised insulin secretion and action, but also by elevated plasma concentrations of the 29-amino acid peptide hormone glucagon, which generally is thought of as a pancreas-derived hormone (produced in and secreted from alpha cells in the islet of Langerhans). In patients with diabetes, circulating glucagon concentrations are elevated in the fasting state and fail to decrease appropriately or even increase in response to ingestion of nutrients. Glucagon is known to be a potent stimulator of hepatic glucose production, and, thus, the elevated glucagon concentrations in diabetes contribute decisively to the predominating trait of patients with diabetes namely hyperglycaemia. Interestingly, studies have shown that while oral intake of glucose results in inappropriately high plasma concentrations of glucagon in patients with diabetes, intravenous (iv) infusion of glucose does not. The mechanisms behind these differential glucagon responses to oral vs. iv glucose administration are currently unexplained. Three hypotheses were tested in the present thesis: 1) Could the inappropriate glucagon response to oral glucose ingestion in patients with diabetes be attributed to the release of glucagonotropic/glucagonostatic peptides secreted from the gut? 2) Could the inappropriate glucagon response to oral glucose ingestion in diabetes be a result of extrapancreatic glucagon secretion (possibly originating from the gut)? And 3) Does the differential glucagon responses between oral and iv glucose administration affect endogenous glucose production (EGP). The overall aim of this PhD thesis was, thus, to investigate the role of the gut in diabetic hyperglucagonaemia and hyperglycaemia. In Study I we examined the effect of the three gut-derived hormones glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) on glucagon secretion in patients with type 2 diabetes. We applied a 50 g-oral glucose tolerance test (OGTT), and five isoglycaemic iv glucose infusions (IIGIs) with either saline, GIP, GLP-1, GLP-2 or a combination of the three hormones. We show that these gut-derived hormones affect glucagon secretion differently and that OGTT-induced secretion of these hormones may play a role in the inappropriate glucagon response to orally ingested glucose in patients with type 2 diabetes with especially GIP acting to increase glucagon secretion. In Study II we examined totally pancreatectomised patients and non-diabetic control subjects during a 75 g-OGTT and an IIGI. We applied sandwich enzyme-linked immunosorbent assay (ELISA) and mass spectrometry-based proteomics for plasma glucagon analysis and show that 29-amino acid glucagon circulates in patients without a pancreas and that glucose stimulation of the gut results in significant hyperglucagonemia in these patients - ultimately confirming the existence of extrapancreatic glucagon secretion in humans. In Study III we examined whether the different responses of insulin and glucagon, respectively, between oral and iv glucose administration translate into differences in EGP and glucose disappearance in patients with type 2 diabetes and non-diabetic control subjects. We applied glucose tracer methodology during a 75 g-OGTT, IIGI and IIGI + iv glucagon (to isolate the effect of glucagon) and show that EGP is less suppressed during OGTT than during IIGI in both patients with type 2 diabetes and non-diabetic control subjects.

Pharmacokinetics and Tolerability of a Single Dose of Semaglutide, a Human Glucagon-Like Peptide-1 Analog, in Subjects With and Without Renal Impairment.

BACKGROUND: The pharmacokinetics and tolerability of semaglutide, a once-weekly human glucagon-like peptide-1 analog in development for the treatment of type 2 diabetes mellitus, were investigated in subjects with/without renal impairment (RI). METHODS: Fifty-six subjects, categorized into renal function groups [normal, mild, moderate, severe, and end-stage renal disease (ESRD)], received a single subcutaneous dose of semaglutide 0.5 mg. Semaglutide plasma concentrations were assessed ≤480 h post-dose; the primary endpoint was the area under the plasma concentration-time curve from time zero to infinity. RESULTS: Semaglutide exposure in subjects with mild/moderate RI and ESRD was similar to that in subjects with normal renal function. In subjects with severe RI, the mean exposure of semaglutide was 22% higher than in subjects with normal renal function, and the 95% confidence interval (1.02-1.47) for the ratio exceeded the pre-specified limits (0.70-1.43). When adjusted for differences in sex, age, and body weight between the groups, all comparisons were within the pre-specified clinically relevant limits. Across RI groups there was no relationship between creatinine clearance (CLCR) and semaglutide exposure, or between CLCR and semaglutide maximum plasma drug concentration (C max). Hemodialysis did not appear to affect the pharmacokinetics of semaglutide. No appreciable changes in safety parameters or vital signs and no serious adverse events were noted. One subject with severe RI reported two major hypoglycemic events. CONCLUSION: When adjusted for differences in sex, age, and body weight, semaglutide exposure was similar between subjects with RI and subjects with normal renal function. Semaglutide (0.5 mg) was well-tolerated. Dose adjustment may not be warranted for subjects with RI. CLINICALTRIALS. GOV IDENTIFIER: NCT00833716.

Absorption, metabolism and excretion of the GLP-1 analogue semaglutide in humans and nonclinical species.

Semaglutide is a human glucagon-like peptide-1 analogue in clinical development for the treatment of type 2 diabetes. The absorption, metabolism and excretion of a single 0.5mg/450µCi [16.7MBq] subcutaneous dose of [3H]-radiolabelled semaglutide was investigated in healthy human subjects and compared with data from nonclinical studies. Radioactivity in blood, plasma, urine and faeces was determined in humans, rats and monkeys; radioactivity in expired air was determined in humans and rats. Metabolites in plasma, urine and faeces were quantified following profiling and radiodetection. The blood-to-plasma ratio and pharmacokinetics of both radiolabelled semaglutide-related material and of semaglutide (in humans only) were assessed. Intact semaglutide was the primary component circulating in plasma for humans and both nonclinical species, accounting for 69-83% of the total amount of semaglutide-related material, and was metabolised prior to excretion. Recovery of excreted radioactivity was 75.1% in humans, 72.1% in rats and 58.2% in monkeys. Urine and faeces were shown to be important routes of excretion, with urine as the primary route in both humans and animals. Semaglutide was metabolised through proteolytic cleavage of the peptide backbone and sequential beta-oxidation of the fatty acid sidechain, and metabolism was not confined to specific organs. Intact semaglutide in urine accounted for 3.1% of the administered dose in humans and less than 1% in rats; it was not detected in urine in monkeys. The metabolite profiles of semaglutide in humans appear to be similar to the profiles from the nonclinical species investigated.

Upregulated absorption of dietary palmitic acids with changes in intestinal transporters in non-alcoholic steatohepatitis (NASH).

BACKGROUND: Palmitic acid is an important risk factor for the pathogenesis of non-alcoholic steatohepatitis (NASH), but changes in palmitic acid intestinal absorption in NASH are unclear. The aim of this study was to clarify changes in palmitic acid intestinal absorption and their association with the pathogenesis of NASH. METHODS: A total of 106 participants were recruited to the study, of whom 33 were control subjects (control group), 32 were patients with NASH Brunt stage 1-2 [early NASH (e-NASH)], and 41 were patients with NASH Brunt stage 3-4 [advanced NASH (a-NASH)]. 13C-labeled palmitate was administered directly into the duodenum of all participants by gastrointestinal endoscopy. Breath 13CO2 levels were measured to quantify palmitic acid absorption, and serum Apolipoprotein B-48 (ApoB-48) concentrations were measured after a test meal to quantify absorbed chylomicrons. Expressions of fatty acid (FA) transporters were also examined. The associations of breath 13CO2 levels with hepatic steatosis, fibrosis and insulin resistance was evaluated using laboratory data, elastography results and liver histology findings. RESULTS: Overall, 13CO2 excretion was significantly higher in e-NASH patients than in the control subjects and a-NASH patients (P < 0.01). e-NASH patients had higher serum ApoB-48 levels, indicating increased palmitic acid transport via chylomicrons in these patients. Jejunal mRNA and protein expressions of microsomal triglyceride transfer protein and cluster of differentiation 36 were also increased in both NASH patient groups. The 13CO2 excretion of e-NASH patients was significantly correlated with the degree of hepatic steatosis, fibrosis and insulin resistance (P = 0.005, P < 0.001, P = 0.019, respectively). CONCLUSIONS: Significantly upregulated palmitic acid absorption by activation of its transporters was evident in patients with NASH, and clinical progression of NASH was related to palmitic acid absorption. These dietary changes are associated with the onset and progression of NASH.

Clinical Pharmacokinetics of Dulaglutide in Patients with Type 2 Diabetes: Analyses of Data from Clinical Trials.

BACKGROUND AND OBJECTIVE: Dulaglutide is a long-acting glucagon-like peptide-1 receptor agonist administered as once-weekly subcutaneous injections for the treatment of type 2 diabetes (T2D). The clinical pharmacokinetics of dulaglutide were characterized in patients with T2D and healthy subjects. METHODS: The pharmacokinetics of dulaglutide were assessed throughout clinical development, including conventional pharmacokinetic analysis in clinical pharmacology studies and population pharmacokinetic analyses of data from combined phase 2 and phase 3 studies in patients with T2D. The effects of potential covariates on dulaglutide population pharmacokinetics were evaluated using nonlinear mixed-effects models. RESULTS: Dulaglutide gradually reached the maximum concentration in 48 h and had a terminal elimination half-life of 5 days. Steady state was achieved between the second and fourth doses. The accumulation ratio was 1.56 for the 1.5 mg dose. Intra-individual variability estimates for the area under the plasma concentration-time curve and the maximum concentration were both <17% [coefficient of variation (CV)]. There was no difference in pharmacokinetics between injection sites (arm, thigh or abdomen). Dulaglutide pharmacokinetics were well described by a two-compartment model with first-order absorption and elimination. The population clearance was estimated at 0.126 L/h [inter-individual variability (CV) 33.8%]. Age, body weight, sex, race and ethnicity did not influence dulaglutide pharmacokinetics to any clinically relevant degree. CONCLUSION: The pharmacokinetics of dulaglutide support once-weekly administration in patients with T2D. The pharmacokinetic findings suggest that dose adjustment is not necessary on the basis of body weight, sex, age, race or ethnicity or site of injection.

Increased gut hormones and insulin sensitivity index following a 3-d intervention with a barley kernel-based product: a randomised cross-over study in healthy middle-aged subjects.

Certain purified indigestible carbohydrates such as inulin have been shown to stimulate gut-derived hormones involved in glycaemic regulation and appetite regulation, and to counteract systemic inflammation through a gut microbiota-mediated mechanism. Less is known about the properties of indigestible carbohydrates intrinsic to food. The aim of this study was to investigate the possibility to affect release of endogenous gut hormones and ameliorate appetite control and glycaemic control by ingestion of a whole-grain cereal food product rich in NSP and resistant starch in healthy humans. In all, twenty middle-aged subjects were provided with a barley kernel-based bread (BB) or a reference white wheat bread during 3 consecutive days, respectively, in a randomised cross-over design study. At a standardised breakfast the following day (day 4), blood was collected for the analysis of blood (b) glucose regulation, gastrointestinal hormones, markers of inflammation and markers of colonic fermentation; 3 d of intervention with BB increased gut hormones in plasma (p) the next morning at fasting (p-glucagon-like peptide-1; 56%) and postprandially (p-glucagon-like peptide-2; 13% and p-peptide YY; 18%). Breath H2 excretion and fasting serum (s) SCFA concentrations were increased (363 and 18%, respectively), and b-glucose (22%) and s-insulin responses (17%) were decreased after BB intervention. Insulin sensitivity index (ISI(composite)) was also improved (25%) after BB. In conclusion, 3 d of intervention with BB increased systemic levels of gut hormones involved in appetite regulation, metabolic control and maintenance of gut barrier function, as well as improved markers of glucose homoeostasis in middle-aged subjects, altogether relevant for the prevention of obesity and the metabolic syndrome.

Circulating levels of apelin, glucagon-like peptide and visfatin in hypercholesterolemic-hyperhomocysteinemic guinea-pigs: their relation with NO metabolism.

The aim of this study was to determine the levels of regulatory peptides apelin, glucagon-like peptide (GLP-1) and visfatin in hypercholesterolemic and hyperhomocysteinemic state and to examine their relation with nitric oxide (NO) metabolism. 32 Male guinea pigs were divided into four groups and each group was fed as follows: (a) commercial chow, (b) cholesterol (chol)-rich diet, (c) methionine (meth)-rich diet, and (d) chol + meth-rich diet. Blood samples were drawn at the end of 10 weeks, and abdominal aorta was dissected for histopathological examination. Serum insulin, GLP-1, apelin, visfatin, and nitrotyrosine concentrations were measured by the manufacturer's kits based on ELISA; asymmetric dimethylarginine (ADMA) and arginine levels were measured by the high performance liquid chromatography. Homocysteine level was measured by the chemiluminescence immunoassay; glucose, total chol and triglyceride levels were measured by the autoanalyzer. The microscopic examination of aorta indicated varying degrees of vascular disturbance in chol- and chol + meth-fed groups. High levels of chol and homocysteine, accompanied with significantly low levels of apelin and GLP-1 were detected in the plasma. Visfatin, ADMA, and nitrotyrosine levels both in chol- and chol + meth-fed groups were significantly higher than those in control animals, whereas arginine and arginine/ADMA ratio were lower. This study indicated that circulating levels of apelin, GLP-1, and visfatin are markedly altered during the development of atherosclerotic changes in close association with chol, homocysteine, NO, and ADMA levels. The measurements of these peptides in serum may help for the diagnosis and follow-up of vascular dysfunction.

Semaglutide, a once-weekly human GLP-1 analog, does not reduce the bioavailability of the combined oral contraceptive, ethinylestradiol/levonorgestrel.

The effect of semaglutide, a once-weekly human glucagon-like peptide-1 (GLP-1) analog in development for type 2 diabetes (T2D), on the bioavailability of a combined oral contraceptive was investigated. Postmenopausal women with T2D (n = 43) on diet/exercise ± metformin received ethinylestradiol (0.03 mg)/levonorgestrel (0.15 mg) once daily for 8 days before (semaglutide-free) and during (steady-state 1.0 mg) semaglutide treatment (subcutaneous once weekly; dose escalation: 0.25 mg 4 weeks; 0.5 mg 4 weeks; 1.0 mg 5 weeks). Bioequivalence of oral contraceptives was established if 90%CI for the ratio of pharmacokinetic parameters during semaglutide steady-state and semaglutide-free periods was within prespecified limits (0.80-1.25). The bioequivalence criterion was met for ethinylestradiol area under the curve (AUC0-24 h ) for semaglutide steady-state/semaglutide-free; 1.11 (1.06-1.15). AUC0-24 h was 20% higher for levonorgestrel at semaglutide steady-state vs. semaglutide-free (1.20 [1.15-1.26]). Cmax was within bioequivalence criterion for both contraceptives. Reductions (mean ± SD) in HbA1c (-1.1 ± 0.6%) and weight (-4.3 ± 3.1 kg) were observed. Semaglutide pharmacokinetics were compatible with once-weekly dosing; the semaglutide dose and dose-escalation regimen were well tolerated. Adverse events, mainly gastrointestinal, were mild to moderate in severity. Asymptomatic increases in mean amylase and lipase were observed. Three subjects had elevated alanine aminotransferase levels ≥3x the upper limit of normal during semaglutide/oral contraceptive coadministration, which were reported as adverse events, but resolved during follow-up. Semaglutide did not reduce the bioavailability of ethinylestradiol and levonorgestrel.

[Secretion of incretin hormones in people having risk factors for type 2 diabetes mellitus].

AIM: To study the secretion of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP),and glucagon- like peptide 2 (GLP-2) in response to a carbohydrate load in people with risk factors for type 2 diabetes mellitus (DM2) in relation to the type of carbohydrate metabolic disturbances and age. SUBJECTS AND METHODS: One hundred and twenty-seven patients having DM2 risk factors who had not previously received glucose- lowering therapy underwent an oral glucose tolerance test (OGTT). The plasma levels of glucose, insulin, glucagon, GLP-1, GIP, and GLP-2 were determined at 0, 30, and 120 minutes of the test. RESULTS: According to the findings, the patients were divided into 3 groups: 1) normal glucose tolerance; 2) prediabetic states (impaired glucose tolerance and/or impaired fasting glycemia); 3) new-onset DM2. OGTT showed that the secretion of GLP-1 was lower and that of GIP and GLP-2 was higher in patients with DM2. GLP-1 secretion decreased with patient age. CONCLUSION: During OGTT, there is a statistically significantly difference in the secretion of incretin hormones in persons with varying degrees of carbohydrate metabolic disturbances: the peak GLP-1 secretion is the highest in healthy individuals and lowest in the patients with DM2; on the contrary, the peak GLP2 and GIP secretions are the highest in the patients with DM2. This may suggest that GLP-1 and the two other hormones (GLP-2 and GIP) show opposite effect in the regulatory mechanisms of carbohydrate metabolism. GLP-1 secretion is decreased with age, which may be one of the reasons for the higher prevalence of DM2 among the elderly.

Biomarkers of Alzheimer's disease among Mexican Americans.

BACKGROUND: Mexican Americans are the fastest aging segment of the U.S. population, yet little scientific literature exists regarding the Alzheimer's disease (AD) among this segment of the population. The extant literature suggests that biomarkers of AD will vary according to race/ethnicity though no prior work has explicitly studied this possibility. The aim of this study was to create a serum-based biomarker profile of AD among Mexican American. METHODS: Data were analyzed from 363 Mexican American participants (49 AD and 314 normal controls) enrolled in the Texas Alzheimer's Research & Care Consortium (TARCC). Non-fasting serum samples were analyzed using a luminex-based multi-plex platform. A biomarker profile was generated using random forest analyses. RESULTS: The biomarker profile of AD among Mexican Americans was different from prior work from non-Hispanic populations with regards to the variable importance plots. In fact, many of the top markers were related to metabolic factors (e.g., FABP, GLP-1, CD40, pancreatic polypeptide, insulin-like-growth factor, and insulin). The biomarker profile was a significant classifier of AD status yielding an area under the receiver operating characteristic curve, sensitivity, and specificity of 0.77, 0.92, and 0.64, respectively. Combining biomarkers with clinical variables yielded a better balance of sensitivity and specificity. CONCLUSION: The biomarker profile for AD among Mexican American cases is significantly different from that previously identified among non-Hispanic cases from many large-scale studies. This is the first study to explicitly examine and provide support for blood-based biomarkers of AD among Mexican Americans. Areas for future research are highlighted.

[Characteristics of cytokine and hormone status in patients with diabetes mellitus type 2 during alimentary exposure].

Diabetes mellitus (DM) is a main noninfectious disease, making significant influence on patients quality of life and life time. The medico-social role of diabetes is defined by wide prevalence of a disease in population and high risk of development of incapacitating complications. Therefore, considerable efforts of modern medicine focused on the study of etio-pathogenetic mechanism and the possibility of dietetic correction in this disease. In this review discusses efficacy of dietary therapy in type 2 diabetes, the role of insulin-like growth 1 (IGF-1)/insulin of pathogenesis microvascular complications. The role of inflammation in the development of microvascular complications, in the first place cytokines, act on the insulin signal pathway and affect the intracellular inflammatory kinase cascade was shown. Also, it is shown that adipose tissue inflammation modulates B-cell function and promotes progressive reduction of insulin secretion. When blood glucose levels are elevated, Glucagon-like peptide--1 stimulates insulin secretion, decrease glucagon secretion, improve B-cell function, and slows gastric emptying. It determines the necessity of fulfillment of further researches of cellular and humoral immunity in diabetes mellitus and the development of personal methods in prevention and treatment of this disease.

The peculiar processing of pancreatic hormone glucagon seen in traumatized patients.

BACKGROUND/AIM: The kinetics of the pancreatic hormone glucagon in traumatized patients has not been minutely investigated as well as that of insulin, despite its significant influence on energy metabolism. In the present study, we examined the kinetics of glucagon and glucagon-related peptides assessed by radioimmunoassay, and the molecular forms of these peptides using gel filtration chromatography. In addition, we discuss glucagon processes in the pancreas and intestine in traumatized patients in the early operative days. METHODOLOGY: Twelve traumatized patients who had undergone emergency surgery were enrolled in this study (group S). Ten healthy volunteers were also enrolled as normal control subjects (group C). The serum level of glucagon and glucagon-related peptides were assessed in the early morning fasting state in both groups, on the second postoperative day in group S, using the glucagon nonspecific N-terminal (glucagon-like immunoreactivity [GLI]) and specific C-terminal (immunoreactive glucagon [IRG]) radioimmunoassays. The molecular forms of these peptides were also estimated using the gel filtration chromatography method. RESULTS: Serum IRG in group S was significantly high compared with that of group C (P < .05). Serum GLI was not significantly different between both groups. In all 12 patients in group S, a peculiar glicentin-like peptide (GLLP: MW approximately 8000 Da) other than pancreatic glucagon was seen on gel filtration chromatography, which was not seen in group C. CONCLUSIONS: The kinetics and processing of glucagon in traumatized patients was different from those of healthy subjects. In traumatized patients, the peculiar processing of glucagon was processed in the intestine, which is different from the ordinary glucagon processing either in the pancreas or the intestine, generating a peculiar glicentin-like peptide (GLLP).

Inappropriate glucagon response after oral compared with isoglycemic intravenous glucose administration in patients with type 1 diabetes.

Hyperglucagonemia following oral glucose ingestion in patients with type 1 diabetes (and type 2 diabetes) has been claimed to result from impaired intraislet insulin inhibition of glucagon. We looked at plasma glucagon responses to the oral glucose tolerance test (OGTT) and isoglycemic intravenous glucose infusion (IIGI) in patients with type 1 diabetes. Nine patients without residual beta-cell function [age: 25 +/- 9 yr; body mass index (BMI): 24 +/- 2 kg/m(2); fasting plasma glucose (FPG): 9.5 +/- 2.1 mM; Hb A(1c): 8.4 +/- 1.2% (mean +/- SD)] and eight healthy subjects (age: 28 +/- 5 yr; BMI: 24 +/- 3 kg/m(2); FPG: 5.3 +/- 0.2 mM; Hb A(1c): 5.0 +/- 0.1%) were examined on two separate occasions: 4-h 50-g OGTT and IIGI. Isoglycemia during IIGIs was obtained using 53 +/- 5 g of glucose in patients with type 1 diabetes and 30 +/- 3 g in control subjects (P < 0.001), resulting in gastrointestinal-mediated glucose disposal [100% x (glucose(OGTT) - glucose(IIGI)/glucose(OGTT))] of -6 +/- 9 and 40 +/- 6% (P < 0.01), respectively. Equal glucagon suppression during the two glucose stimuli was observed in healthy subjects, whereas patients with type 1 diabetes exhibited less inhibition in response to OGTT compared with IIGI (AUC: 1,519 +/- 129 vs. 1,240 +/- 86 pM.4 h; P = 0.03). This difference was even more pronounced during the initial 40 min with paradoxical hypersecretion of glucagon during OGTT and suppression during IIGI (AUC: 37 +/- 13 vs. -33 +/- 16 pM.40 min; P = 0.02). These results suggest that the inappropriate glucagon response to glucose in patients with type 1 diabetes occurs as a consequence of the oral administration way, suggesting a role of the gastrointestinal tract, possibly via glucagonotropic signaling from gut hormones (e.g., glucose-dependent insulinotropic polypeptide), in type 1 diabetic hyperglucagonemia.

Functional ontogeny of the proglucagon-derived peptide axis in the premature human neonate.

BACKGROUND: The regulation of intestinal growth and development in human neonates is incompletely understood, which hinders the provision of nutrients enterally. The "hindgut" hormones glucagon-like peptides 1 and 2 have been shown to play an important role in the regulation of nutrient assimilation, intestinal growth, and function. OBJECTIVE: Our goal was to investigate the production of glucagon-like peptides 1 and 2 in premature human infants and examine the effects of prematurity and feeding on hormone release. PATIENTS AND METHODS: With informed consent, premature infants who were admitted to a tertiary neonatal intensive care nursery (gestational age: 28-32 weeks) were monitored with weekly determinations of postprandial glucagon-like peptide 1 and 2 levels. Comparison studies with groups of normal infants and adults were performed. Hormone levels were obtained by using specific radioimmunoassay for glucagon-like peptide 1 (1-36) and glucagon-like peptide 2 (1-33), modified for small sample volumes; accurate monitoring of enteral intake was performed at all of the sampling time points. RESULTS: Forty-five infants with a mean gestational age of 29.6 +/- 1.9 weeks were studied; fasting levels of both glucagon-like peptides 1 and 2 were elevated. There was no correlation between gestational age and glucagon-like peptide 2 output. However, both glucagon-like peptide 1 and 2 levels were correlated with the caloric value of feeds. CONCLUSIONS: The premature human neonate has significantly higher fasting levels of glucagon-like peptides 1 and 2 compared with adults; feeding increases these levels further. These findings suggest that the proglucagon-derived peptides may have a role in normal intestinal development and nutrient handling.

Effect of fatty acid chain length on suppression of ghrelin and stimulation of PYY, GLP-2 and PP secretion in healthy men.

We have evaluated the effects of fatty acid chain length on ghrelin, peptide YY (PYY), glucagon-like peptide-2 (GLP-2) and pancreatic polypeptide (PP) secretion and hypothesized that intraduodenal administration of dodecanoic ("C12"), but not decanoic ("C10"), acid would decrease plasma ghrelin and increase PYY, GLP-2 and PP concentrations. Plasma hormone concentrations were measured in seven healthy men during 90-min intraduodenal infusions of: (i) C12, (ii) C10 or (iii) control (rate: 2 ml/min, 0.375 kcal/min for C12/C10) and after a buffet-meal consumed following the infusion. C12 markedly suppressed plasma ghrelin and increased both PYY and GLP-2 (all P < 0.05) compared with control and C10, while C10 had no effect. Both C10 and C12 increased PP concentrations slightly (P < 0.05). We conclude that the effects of intraduodenal fatty acids on ghrelin, PYY and GLP-2 secretion are dependent on their chain length.

Plasma concentrations of glucagon-like peptide-2 in adult patients with treated and untreated coeliac disease.

BACKGROUND: Coeliac disease is a common chronic inflammatory enteropathy characterized by villous atrophy and crypt hyperplasia in the small intestine. The mechanism of the intestinal damage in coeliac disease remains unclear. Glucagon-like peptide (GLP)-2 is an enterotrophic peptide that causes crypt hyperplasia and intestinal cell proliferation. We postulate that GLP-2 may be involved in the mucosal changes found in coeliac disease. OBJECTIVES: To study plasma concentrations of GLP-2 in untreated patients with coeliac disease and determine the response to a gluten-free diet (GFD). METHODS: A 440 kcal gluten-free test meal was given to seven controls and 12 coeliac patients at three time intervals: (1) before commencing a GFD; (2) 3 months after a GFD; and (3) 9 months after a GFD. Serial blood sampling was performed over a 2-h period. Each sample was analysed using radioimmunoassay for GLP-2, GLP-1, N-terminal glucagon (N-glucagon) and C-terminal glucagon (C-glucagon). RESULTS: Untreated coeliac patients had significantly higher basal and peak GLP-2 and N-glucagon plasma concentrations compared with controls. After 3 months on a GFD, there was a significant decrease in basal GLP-2 plasma concentrations. There was no significant difference between GLP-1 or C-glucagon in untreated coeliac patients compared with controls. CONCLUSION: This is the first reported study of GLP-2 in coeliac disease. After a GFD there is recovery of the intestine and a reduction in the GLP-2 trophic response. Our findings support the theory that GLP-2 may be part of the mucosal healing and maintenance mechanisms in coeliac disease.

Glucagon-like peptide-2 acutely increases proximal small intestinal blood flow in TPN-fed neonatal piglets.

Glucagon-like peptide-2 (GLP-2) is a gut hormone that is secreted in response to enteral feeding and stimulates small intestinal mucosal growth. We have previously shown that GLP-2 infusion acutely increases portal venous blood flow in TPN-fed piglets. The aim of this study was to localize the vasoactive effect of GLP-2 within the gastrointestinal tissues and other visceral organs in TPN-fed piglets. Tissue blood flow rates were quantified using fluorescent microsphere deposition in anesthetized TPN-fed piglets given intravenous infusion of GLP-2 at either 500 pmol x kg(-1) x h(-1) (low GLP-2, n = 7 pigs) or 2,000 pmol x kg(-1) x h(-1) (high GLP-2, n = 8 pigs) for 2 h. Compared with baseline, the low and the high GLP-2 treatment significantly increased the blood flow rate in the duodenum (+77%) and jejunum (+40% and 80%), respectively, but blood flow to the distal small intestine and colon (-15%) was unchanged or slightly decreased. Baseline mucosal blood flow was five-fold higher than serosal blood flow; however, high GLP-2 treatment increased serosal (+140%) to a larger degree than mucosal blood flow (+73%). The high GLP-2 dose increased pancreatic flow (+34%) but decreased blood flow in the kidneys (-14%) and stomach (-12%), whereas the spleen and brain were unaffected. These findings suggest that the acute GLP-2-mediated stimulation of portal blood flow in TPN-fed piglets occurs principally via increased blood flow through the superior mesenteric artery to the proximal small intestine, a tissue region where the GLP-2R mRNA abundance and trophic GLP-2 effects are greatest.