Curve Of Glucagon Research Articles

Connections between body composition and dysregulation of islet α- and β-cells in type 2 diabetes

BackgroundAccompanying islet α- and β-cell dysregulation in type 2 diabetes (T2D) at the microscopic scale, alterations in body composition at the macroscopic scale may affect the pathogenesis of T2D. However, the connections between body composition and islet α-cell and β-cell functions in T2D have not been thoroughly explored.MethodsFor this cross-sectional study, we recruited a total of 729 Chinese Han patients with T2D in a consecutive manner. Dual-energy X-ray absorptiometry (DXA) was used to measure body composition, which included total bone-free mass, total fat and lean mass, trunk fat and lean mass and limb fat and lean mass. Every patient underwent an oral glucose tolerance test to simultaneously detect glucose, C-peptide and glucagon. The indices of islet α-cell function included fasting glucagon levels and the area under the curve of glucagon after a challenge (AUCglucagon), while the indices of β-cell function included the insulin sensitivity index derived from C-peptide (ISIC-peptide) and the area under the curve of C-peptide after a challenge (AUCC-peptide).ResultsAmong all patients, fat mass, especially trunk fat mass, was significantly correlated with ISIC-peptide and AUCC-peptide levels (r = − 0.330 and 0.317, respectively, p < 0.001), while lean mass, especially limb lean mass, was significantly correlated with fasting glucagon and AUCglucagon levels (r = − 0.196 and − 0.214, respectively, p < 0.001). Moreover, after adjusting for other relevant variables via multivariate linear regression analysis, increased trunk fat mass was independently associated with decreased ISIC-peptide (β = − 0.247, t = − 3.628, p < 0.001, partial R2 = 10.9%) and increased AUCC-peptide (β = 0.229, t = 3.581, p < 0.001, partial R2 = 8.2%), while decreased limb lean mass was independently associated with increased fasting glucagon (β = − 0.226, t = − 2.127, p = 0.034, partial R2 = 3.8%) and increased AUCglucagon (β = − 0.218, t = − 2.050, p = 0.041, partial R2 = 2.3%). Additionally, when separate analyses were performed with the same concept for both sexes, we found that increased trunk fat mass was still independently associated with decreased ISIC-peptide and increased AUCC-peptide, while decreased limb lean mass was still independently associated with increased fasting glucagon and AUCglucagon.ConclusionsIncreased trunk fat mass may partly account for decreased insulin sensitivity and increased insulin secretion, while decreased limb lean mass may be connected to increased fasting glucagon and postprandial glucagon secretion.

The ‘early’ postprandial glucagon response is related to the rate of gastric emptying in type 2 diabetes

Gastric emptying (GE) is a major determinant of the postprandial glycemic and insulinemic responses in health and type 2 diabetes (T2D). However, the effect of GE on the postprandial glucagon response, which is characteristically augmented in T2D, is unknown. This study examined the relationship between plasma glucagon and GE of a standardized mixed meal in individuals with well-controlled T2D. 89 individuals with T2D (HbA1c 6.6 ± 0.1%) consumed a mashed potato meal labeled with 100 µL 13C-octanoic acid between 0 and 5 min. Venous blood was sampled frequently over 4 h for measurements of blood glucose and plasma glucagon. The gastric half-emptying time (T50) was calculated by quantification of 13C in the breath. Blood glucose peaked at t = 90 min after the meal. Plasma glucagon increased to a peak at t = 30 min and then decreased to a nadir at t = 180 min. The T50 was 68.3 ± 1.6 min. The incremental area under the plasma glucagon curve between t = 0–30 min (glucagon iAUC0–30 min) was related inversely to the T50 (r = −0.23, P = 0.029), while the increase in blood glucose at t = 30 min was related directly to the plasma glucagon iAUC0–30 min (r = 0.25, P = 0.018). Accordingly, individuals with relatively faster GE exhibited higher postprandial glucagon and glucose levels (ANOVA: P<0.01 for each). In well-controlled T2D, the early postprandial glucagon response to a mixed meal is related to the rate of GE, and predictive of the initial glycemic response. These observations suggest that a reduction in plasma glucagon may contribute to the effect of dietary and pharmacological strategies which reduce postprandial glycemia in T2D by slowing GE.

Association between osteocalcin, a pivotal marker of bone metabolism, and secretory function of islet beta cells and alpha cells in Chinese patients with type 2 diabetes mellitus: an observational study

BackgroundSeveral recent studies have found that Osteocalcin (OCN), a multifunctional protein secreted exclusively by osteoblasts, is beneficial to glucose metabolism and type 2 diabetes mellitus (T2DM). However, the effects of OCN on islets function especially islet ɑ cells function in patients with type 2 diabetes mellitus characterized by a bi-hormonal disease are still unclear. The purpose of this cross-sectional study was to investigate the relationship between serum OCN and the secretion of islet β cells and ɑ cells in Chinese patients with type 2 diabetes mellitus.Methods204 patients with T2DM were enrolled. Blood glucose (FBG, PBG0.5h, PBG1h, PBG2h, PBG3h), insulin (FINS, INS0.5h, INS1h, INS2h, INS3h), C-peptide (FCP, CP0.5h, CP1h, CP2h, CP3h), and glucagon (GLA0, GLA0.5 h, GLA1h, GLA2h, GLA3h) levels were measured on 0 h, 0.5 h, 1 h, 2 h, and 3 h after a 100 g standard bread meal load. Early postprandial secretion function of islet β cells was calculated as Δcp0.5h = CP0.5-FCP. The patients were divided into low, medium and high groups (T1, T2 and T3) according to tertiles of OCN. Comparison of parameters among three groups was studied. Correlation analysis confirmed the relationship between OCN and pancreatic secretion. Multiple regression analysis showed independent contributors to pancreatic secretion.Main resultsFBG, and PBG2h were the lowest while Δcp0.5h was the highest in the highest tertile group (respectively, p < 0.05). INS3h, area under the curve of insulin (AUCins3h) in T3 Group were significantly lower than T1 Group (respectively, p < 0.05). GLA1h in T3 group was lower than T1 group (p < 0.05), and GLA0.5 h in T3 group was lower than T2 and T1 groups (p < 0.05). Correlation analysis showed OCN was inversely correlated with Homeostatic model of insulin resistance (HOMA-IR), INS3h, AUCins3h (p < 0.05), and was still inversely correlated with FCP, GLA0.5 h, GLA1h, area under the curve of glucagon (AUCgla3h) (respectively, p < 0.05) after adjustment for body mass index (BMI) and alanine aminotransferase (ALT). The multiple regression analysis showed that OCN was independent contributor to Δcp0.5h, GLA0.5h and GLA1h (respectively, p < 0.05).ConclusionsHigher serum OCN level is closely related to better blood glucose control, higher insulin sensitivity, increased early-phase insulin secretion of islet β cells and appropriate inhibition of postprandial glucagon secretion of islet ɑ cells in adult patients with type 2 diabetes mellitus.

Functional Status of Pancreatic α and β Cells in Type 2 Diabetes Mellitus Patients with Different Plasma Triglyceride Levels: A Retrospective Analysis.

Objective To investigate the functional status of pancreatic α and β cells in Type 2 diabetes mellitus (T2DM) patients with different plasma triglyceride (TG) levels. TG levels can be prognostic markers for T2DM. Methods A total of 328 patients with T2DM were divided into three groups according to different TG levels: the TGL group: TG < 1.7 mmol/L; TGM group: 1.7 mmol/L ≤ TG < 2.3 mmol/L; and TGH group: TG ≥ 2.3 mmol/L. An oral glucose tolerance test (OGTT), insulin release test, and glucagon release test were performed in each patient. The changes of glucagon, glucagon/insulin ratio, early insulin secretion index (ΔI30/ΔG30), and area under the insulin curve (AUCI) were compared among each group. Also, the correlations between glucagon and pancreatic β-cell function, glycosylated hemoglobin (HbA1c), and other indices were analyzed. Results With the increase of TG, the fasting and postprandial glucagon levels, the glucagon/insulin ratio, and the area under the glucagon curve (AUCG) presented an increasing trend. The homeostasis model assessment of insulin resistance (HOMA–IR) of the TGH group was significantly increased compared to the TGL and TGM groups. In addition to the increase in TG levels, the insulin sensitivity index (ISI), homeostasis model assessment for β-cell function index (HOMA-β), ΔI30/ΔG30, and AUCI displayed a reducing trend. Glucagon was negatively correlated with ΔI30/ΔG30, high-density lipoprotein (HDL), HOMA-β, body mass index (BMI), ISI, and AUCI (P < 0.05) and positively correlated with fasting blood glucose (FPG), AUCG, HOMA-IR, HbA1c, duration, TG, low-density lipoprotein (LDL), and total cholesterol (TC) (P < 0.05). Conclusion Hypertriglyceridemia aggravated the dysfunction of pancreatic α and β cells. A reasonable control of the TG level makes it easier for blood glucose to reach the standard.

Serum fatty acid-binding protein 4 levels and responses of pancreatic islet \u03b2-cells and \u03b1-cells in patients with type 2 diabetes

BackgroundSerum fatty acid-binding protein 4 (FABP4), as an intracellular lipid chaperone and adipokine, was reported to be related to the incidence of type 2 diabetes (T2D) and diabetic complications, but its association with pancreatic islet β-cell and α-cell functions has not been fully elucidated. So the present study was to investigate the serum FABP4 levels and responses of islet β-cells and α-cells in patients with T2D.Methods115 patients with T2D and 89 healthy controls (HC), who received serum FABP4 levels test, were recruited to participate in this study. Moreover, 75-g oral glucose tolerance test (OGTT) was performed in T2D patients to evaluate islet β-cell and α-cell functions. Systemic insulin sensitivity and overall insulin secretion of islet β-cell function were assessed by Matsuda index using C peptide (ISIM-cp) and ratio of the area under the C peptide curve to the glucose curve (AUCcp/glu) during OGTT, respectively. Fasting glucagon (Gluca0min) and postchallenge glucagon assessed by the area under the glucagon curve (AUCgluca) were determined during OGTT to evaluate islet α-cell function. And other various clinical variables were also measured in all participants. Skewed variables were natural log-transformed (ln), such as lnFABP4.ResultsThe serum FABP4 levels in T2D patients were significantly higher than those in HC (p < 0.05). And after partially adjusting for fasting plasma glucose, serum lnFABP4 levels were negatively correlated with lnISIM-cp (r = − 0.332, p < 0.001) and positively correlated with lnAUCcp/glu (r = 0.324, p < 0.001), lnGluca0min (r = 0.200, p = 0.040) and lnAUCgluca (r = 0.311, p < 0.001), respectively, in patients with T2D. Furthermore, when multiple linear regression analyses were applied to adjust for other various clinical variables, serum lnFABP4 levels were found to remain associated with lnISIM-cp (β = − 0.296, t = − 2.900, p = 0.005), lnAUCcp/glu (β = 0.223, t = 2.038, p = 0.046), lnGluca0min (β = 0.272, t = 2.330, p = 0.024) and lnAUCgluca (β = 0.341, t = 3.065, p = 0.004), respectively.ConclusionIncreased serum FABP4 levels were closely associated with blunted insulin sensitivity, increased insulin secretion, and elevated fasting and postchallenge glucagon levels in patients with T2D.

Pharmacokinetics of Intraperitoneally Delivered Glucagon in Pigs: A Hypothesis of First Pass Metabolism.

Background and ObjectiveArtificial pancreases administering low-dose glucagon in addition to insulin have the scope to improve glucose control in patients with diabetes mellitus type 1. If such a device were to deliver both hormones intraperitoneally, it would mimic normal physiology, which may be beneficial. However, the pharmacokinetic properties of glucagon after intraperitoneal administration are not well known. Hence, the current study aims to evaluate the relationship between the amount of intraperitoneally delivered glucagon and pharmacokinetic variables in a pig model.MethodsPharmacokinetic data was retrieved from experiments on 19 anaesthetised pigs and analysed post hoc. The animals received a single intraperitoneal bolus of glucagon ranging from 0.30 to 4.46 µg/kg. Plasma glucagon was measured every 2–10 min for 50 min.ResultsPeak plasma concentration and area under the time–plasma concentration curve of glucagon correlated positively with the administered dose, and larger boluses provided a relatively greater increase. The mean (standard deviation) time to maximum glucagon concentration in plasma was 11 (5) min, and the mean elimination half-life of glucagon in plasma was 19 (7) min.ConclusionsMaximum plasma concentration and area under the time–plasma concentration curve of glucagon increase nonlinearly in relation to the intraperitoneally administered glucagon dose. We hypothesise that the results are compatible with a satiable first-pass metabolism in the liver. Time to maximum glucagon concentration in plasma and the elimination half-life of glucagon in plasma seem independent of the drug dose.

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.

Association between time in range, a novel measurement of glycemic control and islet secretory function in chinese patients with type 2 diabetes mellitus—An observational study

AimsTo explore the association between dynamic islet secretory function and TIR (time in range), a new valuable metric of glycemic control in type 2 diabetes (T2D). MethodsIn this observational study 256 patients with type 2 diabetes were included and continuous glucose monitoring system (CGMS) were applied to monitor blood glucose and also the calculation of TIR [the time spent in an individual’s target glucose range (usually 3.9–10 mmol/L)]. The participants were divided into 3 groups according to the tertiles of TIR, 85 cases with TIR ≥ 65.05% (T1 group), 86 cases with 41.84 < TIR ≤ 65.05% (T2 group) and 85 cases with TIR < 41.84% (T3 group). Serum glucagon (GLA0h, GLA0.5h, GLA1h, GLA2h, GLA3h), C-peptide (Cp0h, Cp0.5h, Cp1h, Cp2h, Cp3h) concentration at different time points were measured after a 100 g standard steamed buns meal test to assess the pancreatic alpha cell and beta cell function. Spearman correlation analysis and multivariate linear stepwise regression analysis were adopted for statistical analysis. ResultsThe average age and diabetes duration of all the participants were separately 56.09 ± 13.8 years and 8.0 (4.0,15.0) years. Compared with patients in T1 group, participants in group T2 and T3 tend to have a lower concentration of C-peptide at all time points, as well as GLA0h, GLA2h and GLA3h (p < 0.05). TIR was positively correlated with C-peptide at different time points, area under the curve of C-peptide in half an hour (AUCCp0.5h), GLA0h, GLA3h, area under the curve of glucagon in half an hour (AUCGLA0.5h)(rs = 0.263, 0.414, 0.510, 0.587, 0.528, 0.360, 0.259, 0.144 and 0.208, respectively, p < 0.05) and was negatively correlated with the increment of serum glucagon from baseline at 0.5 h, 1 h and 2 h after the standard energy loaded(△GLA0.5h, △GLA1h, △GLA2h)(rs = −0.152,-0.172 and −0.203, respectively, p < 0.05). Cp2h, Cp0h and GLA0h were independent factors for TIR (β = 6.558,-6.930, 0.247, respectively, p < 0.01). ConclusionBoth islet alpha cell and beta cell secretory function have important influence on TIR, a novel vital index of glycemic fluctuation.

Effect of short-term intensive insulin therapy on α-cell function in patients with newly diagnosed type 2 diabetes.

The effect of intensive insulin therapy on hyperglucagonemia in newly diagnosed type 2 diabetes (T2DM), and its associations with β-cell function, has not been elucidated. This study assessed the effect of 12 weeks of intensive insulin therapy on hyperglucagonemia in newly diagnosed T2DM and its associations with β-cell function, with reference to the effects of 12 weeks of oral hypoglycemic agents (OHAs).One hundred eight patients with newly diagnosed T2DM were enrolled from January 2015 to December 2015. The patients were randomly divided to receive, for 12 weeks, either intensive insulin therapy or OHAs. Meal tolerance tests were conducted at baseline before treatment (0 week), at 12 weeks (end of treatment), and 12 months after the initiation of treatment. The levels of glucagon, proinsulin, C-peptide (CP), and blood glucose were measured at timepoints 0, 30, and 120 minutes during the meal tolerance test.Intensive insulin treatment was associated with a decrease in glucagon levels (at 0, 30, and 120 minutes) and proinsulin/CP, and an increase in the insulin-secretion index ΔCP30/ΔG30 and ΔCP120/ΔG120, at 12 weeks and 12 months during the follow-up, compared with the corresponding effects of OHAs. Intensive insulin therapy could reduce but failed to normalize glucagon levels at 12 weeks. There were no correlations between the change of percentages in total area under the curve of glucagon and other glycemic parameters (proinsulin/CP; ΔCP30/ΔG30; or ΔCP120/ΔG120). Patients who received intensive insulin therapy were more likely to achieve their target glycemic goal and remission, compared with those who received OHAs.Short-term intensive insulin therapy facilitates the improvement of both β-cell and α-cell function in newly diagnosed T2DM mellitus. Decline of β-cell secretion and concomitant α-cell dysfunction may both be involved in the pathogenesis of T2DM.

Fasting serum total bile acid levels are associated with insulin sensitivity, islet β-cell function and glucagon levels in response to glucose challenge in patients with type 2 diabetes.

Type 2 diabetes (T2D) is characterized by islet β-cell dysfunction and impaired suppression of glucagon secretion of α-cells in response to oral hyperglycaemia. Bile acid (BA) metabolism plays a dominant role in maintaining glucose homeostasis. So we evaluated the association of fasting serum total bile acids (S-TBAs) with insulin sensitivity, islet β-cell function and glucagon levels in T2D. Total 2,952 T2D patients with fasting S-TBAs in the normal range were recruited and received oral glucose tolerance tests for determination of fasting and postchallenge glucose, C-peptide and glucagon. Fasting and systemic insulin sensitivity were assessed by homeostasis model assessment (HOMA) and Matsuda index using C-peptide, i.e., ISHOMA-cp and ISIM-cp, respectively. Islet β-cell function was assessed by the insulin-secretion-sensitivity-index-2 using C-peptide (ISSI2cp). The area under the glucagon curve (AUCgla) was used to assess postchallenge glucagon. The results showed ISHOMA-cp, ISIM-cp and ISSI2cp decreased, while AUCgla notably increased, across ascending quartiles of S-TBAs but not fasting glucagon. Moreover, S-TBAs were inversely correlated with ISHOMA-cp, ISIM-cp and ISSI2cp (r = -0.21, -0.15 and -0.25, respectively, p < 0.001) and positively correlated with AUCgla (r = 0.32, p < 0.001) but not with fasting glucagon (r = 0.033, p = 0.070). Furthermore, after adjusting for other clinical covariates by multiple linear regression analyses, the S-TBAs were independently associated with ISHOMA-cp (β = -0.04, t = -2.82, p = 0.005), ISIM-cp (β = -0.11, t = -7.05, p < 0.001), ISSI2cp (β = -0.15, t = -10.26, p < 0.001) and AUCgla (β = 0.29, t = 19.08, p < 0.001). Increased fasting S-TBAs are associated with blunted fasting and systemic insulin sensitivity, impaired islet β-cell function and increased glucagon levels in response to glucose challenge in T2D.

Effects of anagliptin on plasma glucagon levels and gastric emptying in patients with type 2 diabetes: An exploratory randomized controlled trial versus metformin

AimsGlucagon has an important role in glucose homeostasis. Recently, a new plasma glucagon assay based on liquid chromatography-high resolution mass spectrometry was developed. We evaluated the influence of a dipeptidyl peptidase-4 inhibitor (anagliptin) on plasma glucagon levels in Japanese patients with type 2 diabetes by using this new assay. MethodsTwenty-four patients with type 2 diabetes were enrolled in a prospective, single-center, randomized, open-label study and were randomly allocated to 4 weeks of treatment with metformin (1000 mg/day) or anagliptin (200 mg/day). A liquid test meal labeled with sodium [13C] acetate was ingested before and after the treatment period. Samples of blood and expired air were collected over 3 h. Plasma levels of glucose, glucagon, C-peptide, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) were measured, and gastric emptying was also evaluated. ResultsTwenty-two patients completed the study (metformin group: n = 10; anagliptin group: n = 12). Glycemic control showed similar improvement in both groups. In the anagliptin group, there was a slight decrease of the incremental area under the plasma concentration versus time curve for glucagon after the test meal (P = 0.048). In addition, the plasma level of active GLP-1 and GIP was increased, and plasma C-peptide was also increased versus baseline. Neither anagliptin nor metformin delayed gastric emptying. ConclusionsIn patients with type 2 diabetes maintained endogenous insulin secretion, anagliptin increased the plasma level of active GLP-1 and GIP in association with a slight stimulation of insulin secretion and slight inhibition of glucagon secretion, but did not delay gastric emptying.Clinical Trial Registry: University hospital Medical Information Network UMIN000028293.

235-LB: Time Course of Pancreatic Alpha-Cell Function in Fulminant Type 1 Diabetes

Aim: We aim to investigate the time course of changes in pancreatic alpha-cells function in patients with newly-onset fulminant type 1 diabetes (FT1D). Methods: Glucagon and C-peptide concentrations were determined in response to 100g steamed bread meal tests (SBMT) in 6 patients with newly-onset FT1D. SBMT were taken every 3 months thereafter until 6 months for 1 FT1D patient and 12 months later for 2 FT1D patients. The area under curve of C-peptide (tAUCc-peptide) and the incremental area under curve of glucagon (iAUCglucagon) were calculated with 0min glucagon as baseline during SBMT. Results: (1) At the onset of disease, tAUCc-peptide in FT1D patients was significantly lower than that of typical autoimmune type 1 diabetes [(217.04 ± 67.47) vs. (1762.00 ± 255.84) pmol/L*h, P&amp;lt;0.0001]. The iAUCglucagon of 4 FT1D patients were higher than patients with typical autoimmune type 1 diabetes [(21.55±8.88) pmol/L*h vs. (6.72±2.92) pmol/L*h, P=0.006], while iAUCglucagon of 2 FT1D patients were lower [1.09, 3.11 pmol/L*h respectively]. And iAUCglucagon of age-matched healthy control [ -(13.16±7.68) pmol/L*h] was much lower. (2) Glucagon secretion in FT1D patients conversely decreased after 12 months of diagnosis, even as early as 6 months. After 6 months of diagnosis, tAUCc-peptide of the FT1D patient did not decrease (456 vs. 692.1 pmol/L*h), while iAUCglucagon drop from 1.09 to (-4.11) pmol/L*h. After 12 months of diagnosis, with islet beta-cells function completely absent, the iAUCglucagon of 2 FT1D patients were 13.64 vs. 12.34 pmol/L*h, 16.52 vs. (-19.42) pmol/L*h at the onset of diabetes and 12 months later respectively. Conclusions: The opposing directions of abnormal glucagon and C-peptide secretion support the dysregulated alpha-cells function in newly-onset FT1D patients. The impaired alpha-cells function may recover in the time course of disease. Disclosure L. Zhang: None. Y. Shi: None. J. Wang: None. X. Wang: None. Y. Qin: None. M. Zhang: None. Funding National Natural Science Foundation of China

SAT-245 Estimated Insulin Sensitivity Score Predicts Post-OSTT Insulin Secretion and GI Hormone Differences in Adolescents with Obesity and PCOS

Women with polycystic ovarian syndrome (PCOS) have an increased risk for type 2 diabetes and obesity increases this risk. Insulin resistance (IR), along with beta-cell failure, is a precursor for diabetes, yet is hard to measure clinically. The estimate of insulin sensitivity (eIS) score (e^[4.647 -0.0203 (waist, cm) - 0.0977 (HbA1c, %) -0.00235 (TG, mg/dl)]) that we previously developed in adolescents utilizes clinical measures. An eIS of <6.3 in obese girls with PCOS represents the ≤50th percentile of insulin sensitivity assessed by hyperinsulinemic euglycemic clamp. Past attempts to prevent progression of dysglycemia in obese youth have suffered from a lack of understanding of postprandial responses across the spectrum of IR. Our goal was to assess differences in post-oral glucose load responses in a cohort of obese girls with PCOS stratified by eIS score. We recruited 55 untreated obese girls with PCOS (age 16 ± 0.2 years, BMI Z-score 2.1 ± 0.04, free testosterone 9.3 ± 0.7 mg/dL). Fasting lipids and hormones were measured followed by a frequently-sampled 6-hr oral sugar tolerance test (OSTT, 75g glucose +25g fructose). Participants were categorized as eIS < or ≥ 6.3. Baseline and post-OSTT responses were compared, including impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) categories. eIS group differences were compared by t-test, and metabolite curves and timepoint differences by repeat measures ANOVA. In this cohort, 67% (N=37) had an eIS score <6.3. The low eIS group was more obese [BMI Z-score 2.23 (2.04, 2.41) vs. 1.77 (1.62, 2.02); p<0.001] and more Hispanic (57% Hispanic vs 16% Hispanic, p=0.01), but was similar in terms of PCOS clinical severity (acne, hirsutism, menses/year and free testosterone). The groups had similar proportions of IFG (13% vs 12%, p=0.80; <6.3 vs ≥6.3) and IGT (49% vs. 29%, p=0.30), but the glucose curve trended to be greater in eIS<6.3 (p=0.05) in particular at times 60 and 90 min. The insulin and c-peptide curves were greater in eIS<6.3 (p=0.01, p=0.002), and the insulin concentrations from timepoints 45-150 min were greater in eIS<6.3. The insulin peak was delayed to 120 min in eIS <6.3 vs. 30 min in eIS≥6.3. The glucagon curve was also greater eIS<6.3 (p=0.01), but the GLP-1 curves were not different (p=0.61).Obese girls with PCOS who had an eIS<6.3 had expected hypersecretion of insulin and c-peptide. The delayed insulin peak and trend for increased glucose at 60-90 min suggest a relatively inadequate first-phase insulin release relative to the degree of IR. Those with a low eIS also had evidence of alpha-cell dysfunction. Insulin hypersecretion was not mediated by increased GLP-1. Understanding these early hormone differences may be key to the development of strategies to prevent progression of dysglycemia in this high-risk population. Funding: BIRCWH K12, NIDDK K23, Boettcher Webb Waring, Doris Duke FCRS, Colorado CTSI, Children’s Hospital Colorado

A prospective study on glucagon responses to oral glucose and mixed meal and 7-year change in fasting glucose.

The role of insufficient glucagon suppression after an oral load in the development of type 2 diabetes mellitus is unclear. The aim of this study was to examine the association between glucagon responses at baseline and fasting glucose levels 7years later. Data of the Hoorn Meal Study were used, an observational cohort study among 121 persons without diabetes with a mean age of 61.1±6.7years and 50% being female. The glucagon response to an oral glucose tolerance test and mixed meal test was expressed as early and late incremental area under the curve. The association with change in fasting glucose levels at follow-up was assessed by linear regression analysis. The early glucagon response following the mixed meal test was associated with an increase in fasting glucose levels of 0.18mmol/L (95%-CI: 0.04-0.31, P=0.01), per unit increase in the incremental area under the curve of glucagon, adjusted for confounders. No significant associations were observed for the late response after the mixed meal test or oral glucose tolerance test. Within a population without diabetes, relative lack of glucagon suppression early after a meal was associated with increased glucose levels over time, suggesting a role of insufficient glucagon suppression in the deterioration of glycaemic control.

Effect of TCF7L2 polymorphism on pancreatic hormones after exenatide in type 2 diabetes

BackgroundGlucagon-like peptide 1 (GLP-1) stimulates insulin secretion and reduces blood glucose in type 2 diabetes mellitus (T2DM). TCF7L2 rs7903146 polymorphism has been associated with decreased insulin secretion, reduced GLP-1 action, and possible impaired peripheral insulin sensitivity.ObjectivesTo evaluate the postprandial pancreatic hormone response in patients with T2DM carriers of the TCF7L2 variant rs7903146 (CT/TT) compared with noncarriers of this variant (CC) after treatment with the GLP-1 agonist exenatide.MethodsIntervention study. Patients with T2DM (n = 162) were genotyped for the TCF7L2 rs7903146 single nucleotide polymorphism (SNP). Individuals with CT/TT and CC genotypes were compared regarding basal serum levels of glucose, glycosylated hemoglobin A1C (HbA1c), HDL, uric acid, insulin, and C-peptide. A subset of 56 individuals was evaluated during a 500-calorie mixed-meal test with measurements of glucose, insulin, proinsulin, C-peptide and glucagon before and after treatment with exenatide for 8 weeks.ResultsPatients with genotypes CC and CT/TT presented similar glucose area under the curve (AUC) 0–180 min before treatment and a similar decrease after treatment (p < 0.001). Before exenatide, insulin levels at 30–120 min were higher in CT/TT versus CC subjects (p < 0.05). After treatment with exenatide, only CT/TT individuals demonstrated insulin reduction at 30–180 min during the meal test (p < 0.05). Patients with the CC genotype presented no differences in insulin concentrations before and after treatment. The areas under the glucagon curve between 0 and 180 min were similar before treatment and reduced after treatment in both groups (p < 0.001).ConclusionsThe presence of the TCF7L2 rs7903146 T allele in patients with T2DM was associated with increased secretion of insulin response to a mixed-meal test. Furthermore, after treatment with exenatide, only the carriers of the T allele showed significantly decreased postprandial plasma insulin peak levels comparing with non carriers.

Effect of liraglutide on glucagon secretion in obese type 2 diabetic patients

Objective: To investigate the effect of liraglutide on glucagon release in obese type 2 diabetes (T2DM). Methods: A multi-center, prospective, and self-comparison study was conducted in four hospitals in Qingdao. Twenty-four patients with T2DM were selected and treated with liraglutide for 12 weeks. Glucagon levels before and after treatment were detected before and 30 min, 60 min and 120 min after meals. Results: After 12 weeks of treatment, the overall level of glucagon decreased, in which the differences in glucagon levels at 30 min [(220±79) ng/L vs. (203±77) ng/L, P<0.05] and 60 min [(248±119) ng/L vs. (203±82)ng/L, P<0.05] reached significance, respectively, comparing to those before treatment. The area under the curve of glucagon after treatment was significantly lower than that before treatment (438±190 vs. 389±153, P<0.05). In contrast, after treatment, the overall level of C-peptide increased, especially the levels at 30 min [(1.53±1.02) nmol/L vs.(2.03±1.29) nmol/L], 60 min [(1.93±1.19) nmol/L vs. (2.48±1.75) nmol/L] and 120 min [(2.36±1.47) nmol/L vs. (2.96±1.84) nmol/L], all P<0.05. The area under C-peptide curve increased significantly (3.6±2.2 vs. 4.6±2.9, P<0.05). Fasting plasma glucose, postprandial 2 h plasma glucose and glycosylated hemoglobin A1c were all lower than before, and the differences were statistically significant (P<0.05). Waist circumference and body mass index were significantly lower than before (P<0.05). The amount of insulin used for the treatment decreased by approximately 55.1% compared with that before liraglutide, and the difference was statistically significant (P<0.05). Conclusions: Liraglutide inhibits glucagon secretion and lowers blood glucose. It can also reduce body weight, improve islet cell function and reduce insulin use in T2DM.

Acarbose Add-on Therapy in Patients with Type 2 Diabetes Mellitus with Metformin and Sitagliptin Failure: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study.

BackgroundWe evaluated the efficacy and safety of acarbose add-on therapy in Korean patients with type 2 diabetes mellitus (T2DM) who are inadequately controlled with metformin and sitagliptin.MethodsA total of 165 subjects were randomized to metformin and sitagliptin (Met+Sita, n=65), metformin, sitagliptin, and acarbose (Met+Sita+Acarb, n=66) and sitagliptin and acarbose (Sita+Acarb, exploratory assessment, n=34) therapy in five institutions in Korea. After 16 weeks of acarbose add-on or metformin-switch therapy, a triple combination therapy was maintained from week 16 to 24.ResultsThe add-on of acarbose (Met+Sita+Acarb group) demonstrated a 0.44%±0.08% (P<0.001 vs. baseline) decrease in glycosylated hemoglobin (HbA1c) at week 16, while changes in HbA1c were insignificant in the Met+Sita group (−0.09%±0.10%, P=0.113). After 8 weeks of triple combination therapy, HbA1c levels were comparable between Met+Sita and Met+Sita+Acarb group (7.66%±0.13% vs. 7.47%±0.12%, P=0.321). Acarbose add-on therapy demonstrated suppressed glucagon secretion (area under the curve of glucagon, 4,726.17±415.80 ng·min/L vs. 3,314.38±191.63 ng·min/L, P=0.004) in the absence of excess insulin secretion during the meal tolerance tests at week 16 versus baseline. The incidence of adverse or serious adverse events was similar between two groups.ConclusionIn conclusion, a 16-week acarbose add-on therapy to metformin and sitagliptin, effectively lowered HbA1c without significant adverse events. Acarbose might be a good choice as a third-line therapy in addition to metformin and sitagliptin in Korean subjects with T2DM who have predominant postprandial hyperglycemia and a high carbohydrate intake.

Contribution of Pancreatic Alpha-Cell Function to Insulin Sensitivity and Glucose Variability in Type 1 Diabetes Patients

In type 1 diabetes (T1D) patients, relationships between pancreatic alpha cell function and glucose metabolism remain elusive. Therefore, we aimed to reveal the contribution of alpha cell function to insulin sensitivity, hepatic glucose uptake (HGU), and glucose variability, including the dawn phenomenon, in T1D patients. We recruited forty Japanese T1D patients with a median (interquartile range) BMI of 21.0 (19.3-22.7) kg/m2, diabetes duration of 2.6 (0.1-10.3) years, and HbA1c level of 8.2 (7.4-10.3) %. We measured the arginine-stimulated glucagon secretion using RIA and double-sandwich ELISA and subsequently assessed the dawn phenomenon using an artificial pancreas (STG-55®, Nikkiso, Japan) and performed a hyperinsulinemic-euglycemic clamp followed by oral glucose loading to evaluate insulin sensitivity and HGU. Glycemic variability was analyzed with continuous glucose monitoring (CGM). The median areas under the curve of glucagon measured by RIA (AUCglcRIA) and ELISA (AUCglcELISA) were 3.7 (2.6-4.6) × 104 and 1.9 (0.8-4.3) × 103 pg/mL × min, respectively. The glucose infusion rate (GIR) during the euglycemic clamp was inversely correlated with AUCglcRIA and AUCglcELISA (R2 = 0.21 and 0.44, P = 0.033 and 0.038, respectively, adjusted for age, sex, and BMI). In addition, the median GIR was significantly lower in the high glucagon response group than in the low glucagon response group [7.3 (5.1-8.4) vs. 9.2 (7.0-11.7), P = 0.049]. The dawn index (ratio of insulin requirements between 4:00-8:00 and 0:00-04:00) and HGU did not correlate AUCglcRIA and AUCglcELISA. The standard deviation of glucose levels determined by CGM significantly correlated with AUCglcRIA (R2 = 0.28, P = 0.015) but not with AUCglcELISA (R2 = 0.01, P = 0.62). In conslusion, alpha cell function may contribute to insulin sensitivity in T1D, and its relationship with glycemic variability may be affected by the procedure of the glucagon assay used. Disclosure N. Takahashi: None. D. Chujo: Research Support; Self; Mitsubishi Tanabe Pharma Corporation, Sanofi K.K., Kyowa Hakko Kirin Co., Ltd.. H. Kajio: None. K. Ueki: Speaker's Bureau; Self; Daiichi Sankyo Company, Limited, Eli Lilly and Company, Boehringer Ingelheim Pharmaceuticals, Inc., MSD K.K., Novo Nordisk Inc., Mitsubishi Tanabe Pharma Corporation, Kyowa Hakko Kirin Co., Ltd., Takeda. Research Support; Self; Takeda, Astellas, Novo Nordisk Inc..

Impact of the Glucagon Assay When Assessing the Effect of Chronic Liraglutide Therapy on Glucagon Secretion.

Glucagon-like peptide-1 agonists acutely lower serum glucagon. However, in the Liraglutide and β-Cell Repair (LIBRA) Trial, 48-week treatment with liraglutide yielded lower/unchanged fasting glucagon but, surprisingly, enhanced postchallenge glucagonemia [measured by R&D Systems (Minneapolis, MN) assay]. Because differences between glucagon assays potentially could explain these unexpected findings, we have remeasured glucagon in all 1222 samples from this trial using the highly-sensitive/specific Mercodia assay to compare the findings between assays. In LIBRA, 51 patients with type 2 diabetes of 2.6 ± 1.9 years duration were randomized to daily subcutaneous liraglutide or placebo injection and followed for 48 weeks, with serial oral glucose tolerance test (OGTT) every 12 weeks (with liraglutide/placebo last administered ∼24 hours earlier). Serum glucagon was measured every 30 minutes on each OGTT, enabling determination of the area under the glucagon curve (AUCglucagon). With the Mercodia assay, fasting glucagon was higher in the liraglutide arm than placebo at 12 weeks (P = 0.01), with no between-group differences at 24, 36, and 48 weeks. There was no difference in AUCglucagon between the groups at any visit. Mercodia and R&D Systems glucagon measurements correlated at postchallenge time points but not at fasting. The Mercodia assay did not replicate the R&D Systems glucagon findings. Although neither assay demonstrated lower postchallenge glucagonemia with chronic liraglutide last administered ∼24 hours earlier, the differential response reported by these assays precludes definitive conclusion and highlights the critical role of assay selection when measuring glucagon in clinical studies.

Decoding the Signaling through Homomeric and Heteromeric Cannabinoid CB1 Receptors

Cannabinoid CB1 receptors are one of the most abundantly expressed G-protein coupled receptors (GPCRs) in the central nervous system and play critical roles in various neurophysiological processes such as reward, emotion and motor activity. Growing evidence supports that GPCRs form heteromers that cause significant changes in their signaling. Utilizing electron microscope immunocytochemistry, CB1 receptors were found to co-localize with dopamine D2 receptors in the somata and dendrites of GABAergic neurons. Furthermore, fluorescence resonance energy transfer and co-immunoprecipitation studies have provided evidence for heteromerization of CB1 and D2 receptors in heterologous expression systems. CB1 receptors primarily signal through Pertussis toxin (PTX) sensitive Gi/o, leading to a decrease in cAMP levels. Interestingly, stimulating the CB1 receptor in a cell line co-expressing CB1 and D2 receptors was shown to increase cAMP levels, suggesting a possible Gs signaling switch through the CB1-D2 heteromer. Our preliminary data using GIRK channels as reporters of GPCR signaling in the Xenopus oocyte heterologous expression system corroborated the Gs switching behavior of CB1 receptors upon heteromerization with D2 receptors. To increase the signal to noise ratio of the CB1 receptor Gs signaling switch, we have turned to a calcium mobilization assay. Naturally, the promiscuous G alpha 16 belongs to the Gq superfamily and its activation leads to phospholipase C activation and calcium release. G alpha 16 chimeras in which 11 or 30 amino acids from the C-terminus were replaced by the corresponding sequence of Go and Gs were constructed. Calcium mobilization was monitored by GCaMP 6s in a FlexStation. We found that activation of Gi-coupled D2 receptor causes increases in intracellular calcium levels with G16/o chimeras but not with G16wt. Gs-coupled Glucagon receptor signal to both G16/s chimeras and G16wt but G16/s chimeras significantly left-shift the dose-response curve of Glucagon, indicating G16/s chimeras as good Gs signaling reporter. We are in the process of testing signaling of homomeric and heteromeric CB1 receptors through G16 chimeras in this system.