Plasma Glucagon Levels Research Articles

Effects of xenin-25 on insulin and glucagon secretions in healthy conscious sheep

The aim of present study was to determine effect of an intravenous injection of xenin-25 on insulin and glucagon secretion in healthy conscious sheep. After feeding once at 17:00, the experiment was started from 9:00 on the next day. Xenin-25 was intravenously (i.v.) injected at a dose of 100 to 1000 pmol/kg with and without the simultaneous injection of glucose at a dose of 200 μmol/kg, and blood was withdrawn before and after the injections. A single xenin-25 injection at 100 and 300 pmol/kg significantly increased the plasma insulin concentration, whereas the 1000 pmol/kg dose did not elicit significantly enhanced insulin response. Plasma glucose and glucagon concentrations did not significantly change after a single xenin-25 injection. Xenin-25 injection significantly and dose-dependently augmented the glucose-induced insulin secretion. However, the changes in the plasma glucose and glucagon level after the glucose injection were not altered by xenin injection. A prior intravenous injection of the neurotensin receptor subtype-1 (NTR-1) antagonist SR 48692 at 100 nmol/kg did not modify the glucose-induced change in plasma insulin caused by xenin-25 at 300 pmol/kg, and intravenous injection of the NTR-2 agonist levocabastine at 1000 pmol/kg did not augment the insulin response to the glucose injection. On the other hand, no xenin-25 immunopositive cells were detected in the ovine pancreas. The mRNAs of the three NTR subtypes were highly expressed in the ovine pancreas in comparison with the expression in the abomasum. These results suggest that xenin-25 released from the upper gastrointestinal tract plays a role of an insulinotropic factor in sheep, possibly through NTRs in the pancreatic islets, but not via NTR-2.

Alpha and Beta Cell Dysfunction Improves With Effective Insulin Therapy in Treatment Naive Type 2 Diabetes - a Prospective Observational Study

: Type 2 diabetes mellitus is characterized by insulin resistance and progressive beta cell decline. Elevated glucagon levels and impaired incretin axis also contribute to the poor glycemic status. Early intensive glycemic control, reduces long-term vascular complications and may preserve β-cell function. Clinical studies of effect of early insulin therapy on combined alpha and beta cell function are lacking. Objective: To determine the effect of early insulin therapy on combined alpha and beta cell dysfunction (islet cell dysfunction) in newly diagnosed type 2 diabetes. Methods: 56 newly diagnosed type 2 diabetes patients, attending the endocrinology OPD at a tertiary teaching hospital were enrolled in this treatment related follow up study after institutional ethical committee clearance, conducted between May 2017 to December 2018. Patients with HbA1C > 8.5% to <12.5% (n=56) were included in the study. Metabolic (FPG, PPG, HbA1c), and Hormonal parameters (plasma glucagon levels,fasting and 2 hour mixed meal stimulated C peptide and levels) were assessed both at baseline and after 6 months of insulin treatment. Initiating dose of insulin was 0.5 U/kg/day and the dose was titrated according to FPG and 2 hr PPG in order to maintain glycemic goals as per ADA standards. Results: The study included 56 subjects with mean age of 41.24 ± 5.64 years and a mean BMI of 25.5 kg/m2. At the end of 6 months of the study, a significant reduction in the mean FPG, PPG, HbA1C were observed,[FPG (139±14.47 mg/dl), PPG (179.89 ± 19.42mg/dl),HbA1c (7.54± 0.63%)] as compared to baseline mean FPG, (216.30 ± 42.35 mg/dl),2 hour PPG (338.44 ±62.89 mg/dl), HbA1C (10.39 ± 1.56 %) (p <0.001). Baseline glucagon levels were high (197.68± 49.09 pg/ml), and were significantly reduced at 6 months of insulin therapy (107.06±49.09 pg/ml).(p <0.001). In comparison to the baseline a significant increase in both fasting (0.73±0.27 ng/ml) and stimulated c-peptide (1.54±1.02 ng/ml) (p<0.001) levels was observed at end of the study. Conclusion: Combined alpha and beta cell (Islet) dysfunction prevails in newly diagnosed T2DM. And early insulin therapy significantly improves both these defects. The documentation of this novel beneficial effect on islet cell dysfunction in our study strengthens the concept of early insulin therapy in newly diagnosed Type 2 diabetes patients.

The Difficulty of Post-Operative Surveillance of Calcitonin Negative Medullary Thyroid Cancer

Background: As a differentiated thyroid tumor, medullary thyroid cancer (MTC) typically maintains the secretory function of the c-cells with resultant increase in serum calcitonin level along with frequent elevations in serum chromogranin A (CgA) and carcinoembryonic antigen (CEA). Clinical Presentation: A 71-year-old female with history of multinodular goiter underwent a thyroid nodule biopsy after routine ultrasound surveillance revealed enlargement of two right lower lobe nodules compared with prior imaging. Fine needle aspiration (FNA) of one 3.1 x 1.9 x 2.7 cm right thyroid nodule revealed cellular material composed of spindle-shaped neoplastic cells, some of them with marked cytologic atypia, suspicious for a neuroendocrine tumor, specifically medullary thyroid carcinoma. A PET/CT scan was performed after injection of Gallium-68 dotatate radiotracer and revealed intense focal radiotracer activity in the approximately 2.5 x 2.1 cm right thyroid mid lower pole heterogeneous hypodense mass with tiny calcification inferiorly, consistent with the patient’s known tumor. There was no evidence of cervical octreotate avid metastatic lymphadenopathy and a chest x-ray showed no evidence of active pulmonary disease. The patient subsequently underwent a right partial thyroidectomy with isthmusectomy. Histopathology revealed a 2.8 x 1.9 x 1.9 cm neoplasm composed of spindle and polygonal cells growing in solid nests with neuroendocrine-type nuclei. Immunostains showed the tumor to be positive for AE1-AE3 cytokeratins, chromogranin, synaptophysin and CEA. It was focally positive for TTF-1 and calcitonin. Thyroglobulin and PAX-8 were negative. Using the AJCC 8th edition staging system, the tumor was staged a pT2Nx with margins uninvolved by carcinoma and no extrathyroidal extension or lymphatic invasion. Angioinvasion was present. Additional serum studies included a normal calcitonin value of <2.0 pg/ml (reference range 0-5.1 pg/ml), CEA 2.6 ng/ml (reference range <6.0 ng/ml), and a mildly elevated chromagranin A at 133 ng/ml (reference range 0-95 ng/ml). Plasma metanephrines, normetanephrines, vasoactive peptide, and glucagon levels were all unremarkable. Our patient’s surgical recovery was normal and two months later she remained asymptomatic without evidence of recurrence or metastasis. Discussion: The diagnosis and post-operative surveillance of medullary thyroid cancer is challenging; even more complicated is the rare case of calcitonin-negative MTC. The cause of calcitonin-negative MTC remains unclear. Further studies are needed for the discovery and development of novel biomarkers for post-operative surveillance and evaluation of clinical relapse.

Glucagon Activates mTOR1/2 Signaling via an EPAC/Rap1 Signaling Axis in Hepatocyte Cultures

Activation of the protein kinase mTOR (mechanistic target of rapamycin) in complex 1/2 (mTORC1/2) in the liver is repressed during fasting and rapidly stimulated in response to feeding. The effect of a meal on hepatic mTORC1/2 is largely mediated by an increase in plasma levels of nutrients (i.e. amino acids) and growth factors (i.e. insulin). By contrast, fasting is associated with elevated plasma levels of glucagon, which is conventionally viewed as playing a counter-regulatory role to insulin. However, glucagon and insulin secretion are both rapidly increased by consumption of a protein meal. In fact, amino acid-induced glucagon secretion is many times greater than that seen with fasting. Herein we investigated the impact of insulin and glucagon on mTORC1/2 activation in rat H4IIE and human HepG2 cell cultures. As expected, insulin enhanced phosphorylation of the mTORC1 substrates p70S6K1 and 4E-BP1. Surprisingly, the effect of glucagon on mTORC1 signaling was biphasic, wherein there was an acute increase in phosphorylation of p70S6K1 and 4E-BP1 over the first hour of exposure, followed by latent suppression. Notably, the stimulatory effect of glucagon on mTORC1 was not additive with insulin, suggesting a convergent signaling axis. Glucagon-induced mTORC1 activation was associated with enhanced cAMP levels and required activation of the glucagon receptor, PI3K/Akt, and exchange protein activated by cAMP (EPAC). An EPAC-specific cAMP analog as well as PKA inhibition enhanced activation of mTORC1/2. EPAC acts as the guanine nucleotide exchange factor for the small GTPase Rap1, and in H4IIE cultures, transient expression of Rap1 was sufficient to stimulate activation of mTORC1/2. Finally, we found that glucagon addition to culture medium was sufficient to promote Rap1-GTP loading in H4IIE cells. Overall, the findings support that glucagon elicits biphasic regulation of hepatic mTORC1/2 by an EPAC-dependent increase in Rap1-GTP which is followed by a repression of mTORC1.

The Links of Ghrelin to Incretins, Insulin, Glucagon, and Leptin After Bariatric Surgery.

Type 2 diabetes mellitus (T2DM) is one of the most prominent and socially significant problems. The present study aimed to identify the mechanisms of interaction of critical regulators of carbohydrate metabolism using bioinformatics and experimental methods and to assess their influence on the development of T2DM. We conducted an in silico search for the relationship of hormones and adipokines and performed functional annotation of the receptors for ghrelin and incretins. Hormones and adipokines were assessed in the plasma of obese patients with and without T2DM as well as after laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) surgeries. Incretin- and ghrelin-associated functions and metabolic processes were discovered. Low ghrelin levels were observed in obese patients without T2DM compared with healthy volunteers and the other groups. The highest ghrelin levels were observed in obese patients with T2DM. This defense mechanism against insulin resistance could be realized through the receptors G-protein-coupled receptor (GPCR), growth hormone secretagogue receptor (GHSR), and growth hormone-releasing hormone receptor (GHRHR). These receptors are associated with proliferative, inflammatory, and neurohumoral signaling pathways and regulate responses to nutrient intake. Signaling through the GPCR class unites ghrelin, glucagon, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide (GLP)-1. Ghrelin impairs carbohydrate and lipid metabolism in obese patients. Ghrelin is associated with elevated plasma levels of insulin, glucagon, and leptin. Specific activation of receptors and modulation by posttranslational modifications of ghrelin can control IR’s development in obesity, which is a promising area for research.

Glucagon transiently stimulates mTORC1 by activation of an EPAC/Rap1 signaling axis

Activation of the protein kinase mechanistic target of rapamycin (mTOR) in both complexes 1 and 2 (mTORC1/2) in the liver is repressed during fasting and rapidly stimulated in response to a meal. The effect of feeding on hepatic mTORC1/2 is attributed to an increase in plasma levels of nutrients, such as amino acids, and insulin. By contrast, fasting is associated with elevated plasma levels of glucagon, which is conventionally viewed as having a counter-regulatory role to insulin. More recently an expanded role for glucagon action in post-prandial metabolism has been demonstrated. Herein we investigated the impact of insulin and glucagon on mTORC1/2 activation. In H4IIE and HepG2 cultures, insulin enhanced phosphorylation of the mTORC1 substrates S6K1 and 4E-BP1. Surprisingly, the effect of glucagon on mTORC1 was biphasic, wherein there was an acute increase in phosphorylation of S6K1 and 4E-BP1 over the first hour of exposure, followed by latent suppression. The transient stimulatory effect of glucagon on mTORC1 was not additive with insulin, suggesting convergent signaling. Glucagon enhanced cAMP levels and mTORC1 stimulation required activation of the glucagon receptor, PI3K/Akt, and exchange protein activated by cAMP (EPAC). EPAC acts as the guanine nucleotide exchange factor for the small GTPase Rap1. Rap1 expression enhanced S6K1 phosphorylation and glucagon addition to culture medium promoted Rap1-GTP loading. Signaling through mTORC1 acts to regulate protein synthesis and we found that glucagon promoted an EPAC-dependent increase in protein synthesis. Overall, the findings support that glucagon elicits acute activation of mTORC1/2 by an EPAC-dependent increase in Rap1-GTP.

SHORT-TERM CRIZOTINIB TREATMENT REVERSES GLUT4 GLUCOSE TRANSPORTER DOWNREGULATION IN DIABETIC RAT HEART

Objective: Crizotinib is a multitarget ALK/c-MET/ROS1/RON inhibitor that can potentially inhibit non-intended receptor tyrosine kinases (RTKs) which play a role in cardiac development, function and/or metabolism. Tyrosine kinase inhibitors (TKIs) studies in diabetic patients showed antidiabetic effects of some TKIs and several potential mechanisms were suggested including mechanisms via RTKs. We examined RTKs after short-term crizotinib treatment in diabetic heart. Design and method: To induce diabetes, male Wistar rats were injected with streptozotocin (STZ; 80 mg/kg, i.p.), controls received vehicle (CON). After 3 days, diabetic rats were treated with crizotinib in a dose 25 mg/kg/day p.o. (STZ+CRI) or vehicle p.o. for 7 days (STZ). mRNA expression of selected RTKs were assessed by RT-qPCR method in rat left ventricle samples. Blood glucose, c-peptide and glucagon in plasma samples and expression of cardiac glucose transporters Glut1 and Glut4 were assessed to determine impact on glucose homeostasis. Results: Intriguingly, crizotinib had a hypoglycaemic effect in diabetic animals (plasma glucose in STZ: 19.2 mmol/L vs. STZ+CRI: 14.5 mmol/L., P&lt;0.05). STZ animals had lower c-peptide and unaltered glucagon plasma levels. However, plasma levels of c-peptide and glucagon were not changed after crizotinib treatment suggesting altered glucose utilization in tissues. In STZ rats, we detected downregulation of insulin dependent glucose transporter Glut4 (by 40% as compared to CON, P &lt; 0.05). Interestingly, crizotinib prevented this downregulation. Insulin non-dependent Glut1 glucose transporter remained stable across all groups. Diabetes upregulated cardiac insulin receptor and Igf-1 receptor without significant crizotinib impact. Regarding RTKs, we observed unaltered c-Met, Flt1 and Erbb2 expressions in diabetic hearts without influence of crizotinib. Conclusions: Crizotinib had a hypoglycaemic effect in diabetic animals after short-term treatment. This was independent of insulin and glucagon levels. Crizotinib prevented cardiac insulin-dependent Glut4 decrease. Downregulation of cardiac insulin receptor family RTKs expression remains stable under crizotinib suggesting modulation of alternative pathways responsible for crizotinib action in diabetic rat heart.

Newcastle Disease Virus Induced Pathologies Severely Affect the Exocrine and Endocrine Functions of the Pancreas in Chickens.

Newcastle disease virus (NDV) causes a highly contagious and devastating disease in poultry. ND causes heavy economic losses to the global poultry industry by decreasing the growth rate, decrease in egg production high morbidity and mortality. Although significant advances have been made in the vaccine development, outbreaks are reported in vaccinated birds. In this study, we report the damage caused by NDV infection in the pancreatic tissues of vaccinated and specific-pathogen-free chickens. The histopathological examination of the pancreas showed severe damage in the form of partial depletion of zymogen granules, acinar cell vacuolization, necrosis, apoptosis, congestion in the large and small vessels, sloughing of epithelial cells of the pancreatic duct, and mild perivascular edema. Increased plasma levels of corticosterone and somatostatin were observed in NDV-infected chicken at three- and five- days post infection (DPI). A slight decrease in the plasma concentrations of insulin was noticed at 5 DPI. Significant changes were not observed in the plasma levels of glucagon. Furthermore, NDV infection decreased the activity and mRNA expression of amylase, lipase, and trypsin from the pancreas. Taken together, our findings highlight that NDV induces extensive tissue damage in the pancreas, decreases the activity and expression of pancreatic enzymes, and increases plasma corticosterone and somatostatin. These findings provide new insights that a defective pancreas may be one of the reasons for decreased growth performance after NDV infection in chickens.

Associations of Plasma Glucagon Levels with Estimated Glomerular Filtration Rate, Albuminuria and Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus.

BackgroundType 2 diabetes mellitus (T2DM) is characterized by elevated fasting glucagon and impaired suppression of postprandial glucagon secretion, which may participate in diabetic complications. Therefore, we investigated the associations of plasma glucagon with estimated glomerular filtration rate (eGFR), albuminuria and diabetic kidney disease (DKD) in T2DM patients.MethodsFasting glucagon and postchallenge glucagon (assessed by area under the glucagon curve [AUCgla]) levels were determined during oral glucose tolerance tests. Patients with an eGFR <60 mL/min/1.73 m2 and/or a urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g who presented with diabetic retinopathy were identified as having DKD.ResultsOf the 2,436 recruited patients, fasting glucagon was correlated with eGFR and UACR (r=–0.112 and r=0.157, respectively; P<0.001), and AUCgla was also correlated with eGFR and UACR (r=–0.267 and r=0.234, respectively; P<0.001). Moreover, 31.7% (n=771) presented with DKD; the prevalence of DKD was 27.3%, 27.6%, 32.5%, and 39.2% in the first (Q1), second (Q2), third (Q3), and fourth quartile (Q4) of fasting glucagon, respectively; and the corresponding prevalence for AUCgla was 25.9%, 22.7%, 33.7%, and 44.4%, respectively. Furthermore, after adjusting for other clinical covariates, the adjusted odds ratios (ORs; 95% confidence intervals) for DKD in Q2, Q3, and Q4 versus Q1 of fasting glucagon were 0.946 (0.697 to 1.284), 1.209 (0.895 to 1.634), and 1.521 (1.129 to 2.049), respectively; the corresponding ORs of AUCgla were 0.825 (0.611 to 1.114), 1.323 (0.989 to 1.769), and 2.066 (1.546 to 2.760), respectively. Additionally, when we restricted our analysis in patients with glycosylated hemoglobin <7.0% (n=471), we found fasting glucagon and AUCgla were still independently associated with DKD.ConclusionBoth increased fasting and postchallenge glucagon levels were independently associated with DKD in T2DM patients.

Transdermal delivery of a somatostatin receptor type 2 antagonist using microneedle patch technology for hypoglycemia prevention.

Hypoglycemia is a serious and potentially fatal complication experienced by people with insulin-dependent diabetes. The complication is usually caused by insulin overdose, skipping meals, and/or excessive physical activities. In type 1 diabetes (T1D), on top of impaired pancreatic α-cells, excessive levels of somatostatin from δ-cells further inhibit glucagon secretion to counteract overdosed insulin. Herein, we aimed to develop a microneedle (MN) patch for transdermal delivery of a peptide (PRL-2903) that antagonizes somatostatin receptor type 2 (SSTR2) in α-cells. First, we investigated the efficacy of subcutaneously administered PRL-2903 and identified the optimal dose (i.e., the minimum effective dose) and treatment scheduling (i.e., the best administration time for hypoglycemia prevention) in a T1D rat model. We then designed an MN patch using a hyaluronic acid (HA)-based polymer. The possible effect of the polymer on stabilizing the native structure of PRL-2903 was studied by molecular dynamics (MD) simulations. The results showed that the HA-based polymer could stabilize the PRL-2903 structure by restricting water molecules, promoting intra-molecular H-bonding, and constraining torsional angles of important bonds. In vivo studies with an overdose insulin challenge revealed that the PRL-2903-loaded MN patch effectively increased the plasma glucagon level, restored the counter-regulation of blood glucose concentration, and prevented hypoglycemia. The proposed MN patch is the first demonstration of a transdermal microneedle patch designed to deliver an SSTR2 antagonist for the prevention of hypoglycemia. This counter-regulatory peptide delivery system may be applied alongside with insulin delivery systems to provide a more effective and safer treatment for people with insulin-dependent diabetes.

Impaired Suppression of Glucagon in Obese Subjects Parallels Decline in Insulin Sensitivity and Beta-Cell Function.

To examine the relationship between plasma glucagon levels and insulin sensitivity and insulin secretion in obese subjects. Suppression of plasma glucagon was examined in 275 obese Hispanic Americans with varying glucose tolerance. All subjects received a 2-hour oral glucose tolerance test (OGTT) and a subset (n = 90) had euglycemic hyperinsulinemic clamp. During OGTT, we quantitated suppression of plasma glucagon concentration, Matsuda index of insulin sensitivity, and insulin secretion/insulin resistance (disposition) index. Plasma glucagon suppression was compared between quartiles of insulin sensitivity and beta-cell function. Fasting plasma glucagon levels were similar in obese subjects with normal glucose tolerance (NGT), prediabetes, and type 2 diabetes (T2D), but the fasting glucagon/insulin ratio decreased progressively from NGT to prediabetes to T2D (9.28 ± 0.66 vs 6.84 ± 0.44 vs 5.84 ± 0.43; P < 0.001). Fasting and 2-hour plasma glucagon levels during OGTT progressively increased and correlated positively with severity of insulin resistance (both Matsuda index and euglycemic hyperinsulinemic clamp). The fasting glucagon/insulin ratio declined with worsening insulin sensitivity and beta-cell function, and correlated with whole-body insulin sensitivity (Matsuda index, r = 0.81; P < 0.001) and beta-cell function (r = 0.35; P < 0.001). The glucagon/insulin ratio also correlated and with beta-cell function during OGTT at 60 and 120 minutes (r = -0.47; P < 0.001 and r = -0.32; P < 0.001). Insulin-mediated suppression of glucagon secretion in obese subjects is impaired with increasing severity of glucose intolerance and parallels the severity of insulin resistance and beta-cell dysfunction.

Impact of glucagon response on early postprandial glucose excursions irrespective of residual β-cell function in type 1 diabetes: A cross-sectional study using a mixed meal tolerance test.

Aims/IntroductionControlling postprandial glucose levels in patients with type 1 diabetes is challenging even under the adequate treatment of insulin injection. Recent studies showed that dysregulated glucagon secretion exacerbates hyperglycemia in type 2 diabetes patients, but little is known in type 1 diabetes patients. We investigated whether the glucagon response to a meal ingestion could influence the postprandial glucose excursion in patients with type 1 diabetes.Materials and MethodsWe enrolled 34 patients with type 1 diabetes and 23 patients with type 2 diabetes as controls. All patients underwent a liquid mixed meal tolerance test. We measured levels of plasma glucose, C‐peptide and glucagon at fasting (0 min), and 30, 60 and 120 min after meal ingestion. All type 1 diabetes patients received their usual basal insulin and two‐thirds of the necessary dose of the premeal bolus insulin.ResultsThe levels of plasma glucagon were elevated and peaked 30 min after the mixed meal ingestion in both type 1 diabetes and type 2 diabetes patients. The glucagon increments from fasting to each time point (30, 60 and 120 min) in type 1 diabetes patients were comparable to those in type 2 diabetes patients. Among the type 1 diabetes patients, the glucagon response showed no differences between the subgroups based on diabetes duration (<5 vs ≥5 years) and fasting C‐peptide levels (<0.10 vs ≥0.10 nmol/L). The changes in plasma glucose from fasting to 30 min were positively correlated with those in glucagon, but not C‐peptide, irrespective of diabetes duration and fasting C‐peptide levels in patients with type 1 diabetes.ConclusionsThe dysregulated glucagon likely contributes to postprandial hyperglycemia independent of the residual β‐cell functions during the progression of type 1 diabetes.

Plasma levels of glucagon but not GLP-1 are elevated in response to inflammation in humans.

ObjectiveGlucagon and glucagon-like peptide-1 (GLP-1) originate from the common precursor, proglucagon, and their plasma concentrations have been reported to be increased during inflammatory conditions. Increased blood glucose levels are frequently observed in septic patients, and therefore we hypothesized that glucagon, but not GLP-1, is increased in individuals with inflammation.DesignProspective longitudinal cohort study.Materials and methodsWe measured glucagon and GLP-1 in plasma sampled consecutively in three cohorts consisting of patients with infective endocarditis (n = 16), urosepsis (n = 28) and post-operative inflammation following percutaneous aortic valve implantation or thoracic endovascular aortic repair (n = 5). Correlations between C-reactive protein (CRP), a marker of systemic inflammation, and glucagon and GLP-1 concentrations were investigated. Additionally, glucagon and GLP-1 concentrations were measured after a bolus infusion of lipopolysaccharide (LPS, 1 ng/kg) in nine healthy young males.ResultsGlucagon and CRP were positively and significantly correlated (r = 0.27; P = 0.0003), whereas no significant association between GLP-1 and CRP was found (r = 0.08, P = 0.30). LPS infusion resulted in acute systemic inflammation reflected by increased temperature, pulse, tumor necrosis factor-α (TNFα), interleukin-6 (IL-6) and concomitantly increased concentrations of glucagon (P < 0.05) but not GLP-1.ConclusionsSystemic inflammation caused by bacterial infections or developed as a non-infected condition is associated with increased plasma concentration of glucagon, but not GLP-1. Hyperglucagonemia may contribute to the impaired glucose control in patients with systemic inflammatory diseases.

Genome-wide association study of circulating levels of glucagon during an oral glucose tolerance test

BackgroundIn order to explore the pathophysiology underlying type 2 diabetes we examined the impact of gene variants associated with type 2 diabetes on circulating levels of glucagon during an oral glucose tolerance test (OGTT). Furthermore, we performed a genome-wide association study (GWAS) aiming to identify novel genomic loci affecting plasma glucagon levels.MethodsPlasma levels of glucagon were examined in samples obtained at three time points during an OGTT; 0, 30 and 120 min, in two separate cohorts with a total of up to 1899 individuals. Cross-sectional analyses were performed separately in the two cohorts and the results were combined in a meta-analysis.ResultsA known type 2 diabetes variant in EYA2 was significantly associated with higher plasma glucagon level at 30 min during the OGTT (Beta 0.145, SE 0.038, P = 1.2 × 10–4) corresponding to a 7.4% increase in plasma glucagon level per effect allele. In the GWAS, we identified a marker in the MARCH1 locus, which was genome-wide significantly associated with reduced suppression of glucagon during the first 30 min of the OGTT (Beta − 0.210, SE 0.037, P = 1.9 × 10–8), equivalent to 8.2% less suppression per effect allele. Nine additional independent markers, not previously associated with type 2 diabetes, showed suggestive associations with reduced glucagon suppression during the first 30 min of the OGTT (P < 1.0 × 10–5).ConclusionsA type 2 diabetes risk variant in the EYA2 locus was associated with higher plasma glucagon levels at 30 min. Ten additional variants were suggestively associated with reduced glucagon suppression without conferring increased type 2 diabetes risk.

The liver\u2013alpha cell axis associates with liver fat and insulin resistance: a validation study in women with non-steatotic liver fat levels

Aims/hypothesisMany individuals who develop type 2 diabetes also display increased glucagon levels (hyperglucagonaemia), which we have previously found to be associated with the metabolic syndrome. The concept of a liver–alpha cell axis provides a possible link between hyperglucagonaemia and elevated liver fat content, a typical finding in the metabolic syndrome. However, this association has only been studied in individuals with non-alcoholic fatty liver disease. Hence, we searched for a link between the liver and the alpha cells in individuals with non-steatotic levels of liver fat content. We hypothesised that the glucagon–alanine index, an indicator of the functional integrity of the liver–alpha cell axis, would associate with liver fat and insulin resistance in our cohort of women with low levels of liver fat.MethodsWe analysed data from 79 individuals participating in the Prediction, Prevention and Subclassification of Type 2 Diabetes (PPSDiab) study, a prospective observational study of young women at low to high risk for the development of type 2 diabetes. Liver fat content was determined by MRI. Insulin resistance was calculated as HOMA-IR. We conducted Spearman correlation analyses of liver fat content and HOMA-IR with the glucagon–alanine index (the product of fasting plasma levels of glucagon and alanine). The prediction of the glucagon–alanine index by liver fat or HOMA-IR was tested in multivariate linear regression analyses in the whole cohort as well as after stratification for liver fat content ≤0.5% (n = 39) or >0.5% (n = 40).ResultsThe glucagon–alanine index significantly correlated with liver fat and HOMA-IR in the entire cohort (ρ = 0.484, p < 0.001 and ρ = 0.417, p < 0.001, respectively). These associations resulted from significant correlations in participants with a liver fat content >0.5% (liver fat, ρ = 0.550, p < 0.001; HOMA-IR, ρ = 0.429, p = 0.006). In linear regression analyses, the association of the glucagon–alanine index with liver fat remained significant after adjustment for age and HOMA-IR in all participants and in those with liver fat >0.5% (β = 0.246, p = 0.0.23 and β = 0.430, p = 0.007, respectively) but not in participants with liver fat ≤0.5% (β = −0.184, p = 0.286).Conclusions/interpretationWe reproduced the previously reported association of liver fat content and HOMA-IR with the glucagon–alanine index in an independent study cohort of young women with low to high risk for type 2 diabetes. Furthermore, our data indicates an insulin-resistance-independent association of liver fat content with the glucagon–alanine index. In summary, our study supports the concept that even lower levels of liver fat (from 0.5%) are connected to relative hyperglucagonaemia, reflecting an imminent impairment of the liver–alpha cell axis.

Impact of malnutrition on systemic immune and metabolic profiles in type 2 diabetes

BackgroundWhile obesity and overweight status are firmly established risk factors for Type 2 diabetes mellitus (T2DM), a substantial proportion of diabetic individuals, especially in Africa and Asia, are often underweight or normal weight. However, very little is known about the immunological and metabolic profiles of these individuals.MethodsThis study aimed to assess the relationship between malnutrition and Type 2 diabetes mellitus (T2DM). We examined a variety of analytes associated with the immunological and metabolic profiles of T2DM individuals with low (< 18.5 kg/m2) or normal (18.5–24.9 kg/m2) body mass index (BMI). To this end, we measured plasma levels of HbA1c, glucose, insulin, glucagon, adipocytokines and Type 1, Type 2, Type 17, pro-inflammatory and regulatory cytokines in T2DM individuals with low BMI (LBMI) or normal BMI (NBMI) with small sample size n = 44 in each group.ResultsLBMI individuals exhibited significantly higher levels of HbA1c, random blood glucose, insulin and glucagon compared to NBMI individuals. Similarly, LBMI individuals exhibited significantly higher levels of adiponectin and adipsin and significantly lower levels of leptin in comparison to NBMI individuals. LBMI individuals also exhibited significantly lower levels of the Type 1, Type 2, Type 17, pro-inflammatory and regulatory cytokines in comparison to NBMI individuals. Finally, while the metabolic parameters exhibited a significant negative correlation with BMI, the immunological parameters exhibited a significant positive correlation with BMI.ConclusionsMalnutrition is associated with a significant modulation of glycemic, hormonal and cytokine parameters in T2DM. Hence, the biochemical and immunological profiles of T2DM is significantly influenced by BMI.

Plasma glucagon levels are associated with obesity, insulin resistance and metabolic syndrome in a general population cohort

Rationale: Glucagon is a well- and long-recognized key regulator of hepatic glucose production playing a major role in plasma glucose control in both type 1 and type 2 diabetes. Experimental models have recently identified a role of glucagon in the regulation of energy balance and intermediate metabolism but potential associations between plasma glucagon, obesity and obesity-associated metabolic complications insulin resistance and metabolic syndrome in general population cohorts is largely unknown.

Imaging of the Glucagon Receptor in Subjects with Type 2 Diabetes

Despite the importance of the glucagon receptor (GCGR) in disease and in pharmaceutical drug development, there is a lack of specific and sensitive biomarkers of its activation in humans. The PET radioligand ⁶⁸Ga-DO3A-VS-Tuna-2 (⁶⁸Ga-Tuna-2) was developed to yield a noninvasive imaging marker for GCGR target distribution and drug target engagement in humans. <b>Methods:</b> The biodistribution and dosimetry of ⁶⁸Ga-Tuna-2 was assessed by PET/CT in 13 individuals with type 2 diabetes as part of a clinical study assessing the occupancy of the dual GCGR/glucagon like peptide-1 receptor agonist SAR425899. Binding of ⁶⁸Ga-Tuna-2 in liver and reference tissues was evaluated and correlated to biometrics (e.g., weight or body mass index) or other biomarkers (e.g., plasma glucagon levels). <b>Results:</b>⁶⁸Ga-Tuna-2 binding was seen primarily in the liver, which is in line with the strong expression of GCGR on hepatocytes. The kidneys demonstrated high excretion-related retention, whereas all other tissue demonstrated rapid washout. The SUV_{55 min} (SUV during the last 10-min time frame, 50–60 min after administration) uptake endpoint was sensitive to endogenous levels of glucagon. ⁶⁸Ga-Tuna-2 exhibited a safe dosimetry profile and no adverse events after intravenous administration. <b>Conclusion:</b>⁶⁸Ga-Tuna-2 can be used for safe and accurate assessment of the GCGR in human. It may serve as an important tool in understanding the in vivo pharmacology of novel drugs engaging the GCGR.

Variation in plasma glucagon levels according to obesity status in Japanese Americans with normal glucose tolerance.

Japanese Americans living in the United States are genetically identical to Japanese people, but have undergone a rapid and intense westernization of their lifestyle. This study investigated variability in glucagon secretion after glucose loading among Japanese Americans with normal glucose tolerance (NGT) according to obesity status. The 75-g oral glucose tolerance test (OGTT) was performed for 138 Japanese Americans (aged 40-75 years) living in Los Angeles. Plasma glucagon levels measured using the sandwich enzyme-linked immunosorbent assay were compared according to body mass index (BMI) categories among 119 individuals with NGT. The individuals were classified into three categories according to their BMI values: <22 kg/m2 (n = 37), 22-24.9 kg/m2 (n = 46), and ≥25 kg/m2 (n = 36). Fasting plasma glucagon levels and glucagon-area under the curve levels during the OGTT were the highest in the BMI ≥25 kg/m2 group. Fasting glucagon levels were correlated with BMI (r = 0.399, p < 0.001), fasting insulin levels (r = 0.275, p = 0.003) and the homeostasis model assessment-insulin resistance (r = 0.262, p = 0.004). In conclusion, our findings suggest that fasting hyperglucagonemia is associated with obesity and insulin resistance even during the NGT stage in the Japanese American population.

Association of Glucagon With Obesity, Glycemic Control and Renal Function in Adults With Type 2 Diabetes Mellitus

ObjectivesIn this study, we used a double-antibody sandwich enzyme-linked immunosorbent assay to assess the association between blood glucagon levels and indices of obesity, glycemic control and renal function in patients with type 2 diabetes mellitus (T2DM). MethodsThis investigation was a cross-sectional study on inpatients with T2DM who had plasma glucagon levels measured during hospitalization. Associations of fasting glucagon levels (G0), 120-minute postbreakfast plasma glucagon (G120), fasting glucagon/C-peptide ratio (G0/CPR0) and postbreakfast glucagon/C-peptide ratio (G120/CPR120) with clinical data were evaluated using multiple regression analysis. ResultsA total of 345 patients were enrolled in the study. G0, and G120 were significantly and positively associated with serum C-peptide levels. Moreover, G0 and G120 were positively associated with waist circumference, and G0 was negatively associated with duration of diabetes mellitus. Interestingly, both G0 and G120 were negatively associated with the estimated glomerular filtration rate. In addition, G120/CPR120 was positively associated with duration of diabetes mellitus and glycoalbumin levels. ConclusionsThe balance between glucagon and insulin secretion is significantly associated with abdominal obesity and important for maintaining glucose homeostasis. Postprandial hyperglucagonemia could also be related to deterioration of renal function.