A depot-forming glucagon-like peptide-1 fusion protein reduces blood glucose for five days with a single injection

Peptide drugs are an exciting class of pharmaceuticals for the treatment of a variety of diseases; however, their short half-life dictates multiple and frequent injections causing undesirable side effects. Herein, we describe a novel peptide delivery system that seeks to combine the attractive features of prolonged circulation time with a prolonged release formulation. This system consists of glucagon-like peptide-1, a type-2 diabetes drug fused to a thermally responsive, elastin-like-polypeptide (ELP) that undergoes a soluble–insoluble phase transition between room temperature and body temperature, thereby forming an injectable depot. We synthesized a set of GLP-1-ELP fusions and verified their proteolytic stability and potency in vitro. Significantly, a single injection of depot forming GLP-1-ELP fusions reduced blood glucose levels in mice for up to 5 days, 120 times longer than an injection of the native peptide. These findings demonstrate the unique advantages of using ELPs to release peptide-ELP fusions from a depot combined with enhanced systemic circulation to create a tunable peptide delivery system.     

Glucagon-like peptide-1 receptor agonists versus insulin glargine for type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

Background: Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of hypoglycemic drugs, including exenatide, liraglutide, albiglutide, lixisenatide, and taspoglutide. Insulin glargine is a standard agent used to supplement basal insulin in type 2 diabetes mellitus (T2DM).Objective: The aim of this study was to review the efficacy and safety profiles of GLP-1 receptor agonists versus insulin glargine in type 2 diabetic patients who have not achieved treatment goals with oral hypoglycemic agents.Methods: The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and the database of ongoing trials were searched from inception through April 2010. Additional data were sought from relevant Web sites, the American Diabetes Association, reference lists of included trials and related (systematic) reviews, and industry. Randomized controlled trials (RCTs) were selected if they were ≥3 months in duration, compared GLP-1 receptor agonists with insulin glargine in patients with T2DM, and included ≥1 of the following outcomes: mortality, complications of T2DM, glycemie control, weight, lipids, blood pressure, adverse effects, and health-related quality of life. Quasirandomized controlled trials were excluded. The quality of the eligible studies was assessed on the basis of the following aspects: randomization procedure, allocation concealment, blinding, incomplete outcome data (intent-to-treat [ITT] analysis), selective outcome reporting, and publication bias.Results: A total of 410 citations were retrieved; 5 multicenter RCTs that met the inclusion criteria were identified. They were all open-label designs with an insulin glargine arm, predefined outcomes reported, and ITT analysis. One trial had an unclear randomization procedure and allocation concealment. Publication bias was not able to be determined. No data wete found with regard to mortality or diabetes-associated complications, and few data were found on quality of life. The results of the metaanalysis suggest that insulin glargine was significantly better in reducing the fasting blood glucose (mean difference [MD] [95% CI], 1.31 [1.04 to 1.58]; P < 0.001), but exhibits greater incidence of nocturnal hypoglycemia (risk ratio [RR] [95% CI], 0.40 [0.23 to 0.71]; P = 0.002) and influenza (RR [95% CI], 0.56 [0.32 to 0.98]; P = 0.04). GLP-1 receptor agonists are more conducive to reducing weight (MD [95% CI], −3.96 [−5.14 to -2.77]; P < 0.001), postprandial blood glucose (after breakfast, P < 0.001; after dinner, P < 0.001), and LDL-C (MD [95% CI], −0.18 [−0.28 to −0.08]; P < 0.001), but have significantly more gastrointestinal adverse effects (eg, nausea/ vomiting, P < 0.001). There were no significant differences between GLP-1 receptor agonists and insulin glargine in reducing glycosylated hemoglobin (HbA_1c) levels (MD [95% CI], −0.03 [−0.13 to 0.08]) and the overall incidence of hypoglycemia (RR [95% CI], 0.69 [0.42 to 1.14]).Conclusions: Compared with insulin glargine, GLP-1 receptor agonists did not have a significant difference in regard to reducing HbA1c levels and they were significantly associated with decreased weight but increased gastrointestinal adverse events. It remains unclear whether GLP-1 receptor agonists influence mortality or diabetes-associated complications in patients with T2DM. More trials with longer follow-up are needed to determine the exact long-term efficacy and safety profiles of this new class of hypoglycemic drugs.     

Protective effect of glucagon-like peptide-1 agents on reperfusion injury for acute myocardial infarction: a meta-analysis of randomized controlled trials

Background: The cardioprotective properties of glucagon-like peptide-1 (GLP-1) receptor agonists in acute myocardial infarction (AMI) patients against reperfusion injury remain unclear. We performed a meta-analysis to assess their role in the acute phase of AMI.

Methods and results: Randomized controlled trials (RCTs) comparing GLP-1 agents with placebo in AMI patients undergoing percutaneous coronary intervention were identified by searching PubMed, Embase and Cochrane libraries. Six RCTs with 800 patients were included in the meta-analysis. Compared with placebo, GLP-1 agents improved left ventricular ejection fraction (LVEF) by 2.46 [95% confidence interval (CI): 0.23–4.70%] and reduced the infarct size in grams as well as in percentage of the area at risk [weighted mean difference (WMD)???5.29, 95% CI: ?10.39 to ?0.19; WMD ?0.08, 95% CI: ?0.12 to ?0.04, respectively]. The incidence of cardiovascular events appeared to be lower with GLP-1 therapy, but the statistical significance was not reached [relative risk (RR): 0.78; 95% CI: 0.58–1.06]. In terms of safety evaluation, GLP-1 treatment increased the risk of gastrointestinal adverse events (RR: 5.50, 95% CI: 2.85–10.60).

Conclusions: Our analysis shows that in patients with AMI undergoing PCI, GLP-1 treatment is associated with improved LVEF and reduced infarct size.     

不同糖耐量水平人群血浆胰高血糖素样肽-1和葡萄糖依赖的促胰岛素样多肽水平比较

目的 了解不同糖代谢状态的人群空腹及口服葡萄糖耐量实验(oral glucose tolerance test,OGTT)餐后胰高血糖素样态-1(GLP-1)和葡萄糖依赖的促胰岛素多态(GIP)水平.方法 将受试者根据OGTT结果分为3组:正常糖耐量组(NGT,n=61例),糖耐量受损组(IGT,n=53)和2型糖尿病...     

Glucagon-like peptide-1 (GLP-1): a trial of treatment in non-insulin-dependent diabetes mellitus

Glucagon-like peptide-1 (7–36) amide (GLP-1) is released from the gut into the circulation after meals and is the most potent physiological insulinotropic hormone in man. In contrast to presently available therapeutic agents for non-insulin-dependent diabetes mellitus (NIDDM), GLP-1 has the advantages of both suppressing glucagon secretion and delaying gastric emptying. We report the first chronic study of subcutaneous (s/c) GLP-1 treatment in NIDDM. Five patients with poorly controlled NIDDM were entered into a six-week, double-blind crossover trial. Each received three weeks treatment with s/c GLP-1 40 nmol or saline, given three times a day immediately before meals. A standardized test meal was given at the beginning and end of each treatment period. GLP-1 reduced plasma glucose area under the curve (AUC) following the standard test meal by 25% (AUC, 0–180 mins, GLP-1 start of treatment 482.2 ± 38.2 vs. saline start of treatment 635.7 ± 45.4 mmol min L⁻¹, F  = 16.4, P  < 0.02). The beneficial effect of GLP-1 on plasma glucose concentration was fully maintained for the three-week treatment period. Plasma glucagon levels were significantly lower for 60 min postprandially after GLP-1 treatment. In this group of patients there was no significant increase in postprandial insulin levels with GLP–1. We have demonstrated a significant improvement in postprandial glycaemic control with s/c GLP-1 treatment that was fully maintained over a three-week treatment period. GLP-1 improves glycaemic control even in the absence of an insulinotropic effect and is a potential treatment for NIDDM.     

糖尿病患者胰高血糖素样肽-1在糖耐量试验前后的变化及意义

目的探讨2型糖尿病患者胰高血糖素样肽-1(glucagon-like peptical-1,GLP-1)水平与血糖、胰岛素及胰岛素抵抗的关系。方法 2型糖尿病患者50例(糖尿病组)及体检健康者30例(对照组),2组均禁食10h后行糖耐量试验,采集空腹及餐后2h血标本,分别检测血浆葡萄糖、胰岛素、GLP-1水平。结果糖尿病组空腹及餐后2h血糖明显高于对照组(P<0.05),餐后2hGLP-1水平明显低于对照组(P<0.05),空腹和餐后2h胰岛素水平及空腹GLP-1水平与对照组比较差异无统计学意义(P>0.05)。结论 2型糖尿病患者餐后2hGLP-1水平较正常人明显降低;餐后GLP-1分泌水平可反映2型糖尿病患者胰岛功能受损程度。     

糖尿病患者胰高血糖素样肽-1在糖耐量试验前后的变化及意义

目的探讨2型糖尿病患者胰高血糖素样肽-1（glucagon-like peptical-1,GLP-1）水平与血糖、胰岛素及胰岛素抵抗的关系。方法 2型糖尿病患者50例（糖尿病组）及体检健康者30例（对照组）,2组均禁食10h后行糖耐量试验,采集空腹及餐后2h血标本,分别检测血浆葡萄糖、胰岛素、GLP-1水平。结果糖尿病组空腹及餐后2h血糖明显高于对照组（P〈0.05）,餐后2hGLP-1水平明显低于对照组（P〈0.05）,空腹和餐后2h胰岛素水平及空腹GLP-1水平与对照组比较差异无统计学意义（P〉0.05）。结论 2型糖尿病患者餐后2hGLP-1水平较正常人明显降低;餐后GLP-1分泌水平可反映2型糖尿病患者胰岛功能受损程度。     

Classification of dynamical diseases by new mathematical tools: Application of multi-dimensional phase space analyses to the pulsatile secretion of parathyroid hormone

The biological importance of dynamic hormonal secretion has been demonstrated. There is good evidence from recent studies that parathyroid hormone (PTH) which plays an important role in bone physiology is secreted in a pulsatile manner. In this study we performed a classification of two 'dynamical diseases' namely osteoporosis and hyperparathyroidism by the visualization of dynamic PTH-secretion in multidimensional phase spaces.     

Relationship of insulin clearance and secretion to insulin sensitivity in non-diabetic Mexican Americans

The antecedents of type II diabetes, while still controversial, are thought to involve decreased insulin sensitivity and compensatory hypersecretion of insulin. Mexican Americans have a three-fold excess risk of type II diabetes and non-diabetic Mexican Americans are characterized by hyperinsulinaemia and insulin resistance. Few data exist, however, on whether there are defects in insulin secretion and/or clearance in this population. We examined insulin sensitivity, secretion and clearance using combined insulin and C-peptide measurements analysed by the minimal model technique of Bergman and colleagues in 10 non-obese, normoglycaemic Mexican Americans and 11 age, sex and obesity-matched non-Hispanic whites. Mexican Americans had significantly decreased insulin sensitivity (SI 4.06 s. 7.56, P = 0.017), higher first phase insulin secretion (1.03 nM vs. 0.72 nM) and decreased insulin clearance (0.099 vs. 0.161) than non-Hispanic whites. Thus, normal Mexican Americans have higher rather than lower insulin secretion suggesting that lower insulin sensitivity may be an early defect in this ethnic group. In addition, they have reduced insulin clearance. Moreover, insulin sensitivity and insulin clearance were positively correlated. We thus speculate that decreased insulin clearance may represent a further autoregulatory mechanism in addition to increased insulin secretion to compensate for decreased insulin sensitivity.     

Polymorphism at the 5'' end flanking region of the insulin gene is associated with reduced insulin secretion in healthy individuals

Sixty-four unrelated healthy subjects were studied for the detection of a DNA polymorphism at the 5' end of the insulin gene. No significant difference between the groups was found in blood glucose values at fasting and after an oral glucose load. A significant association was found between fasting (P less than 0.05) and after load plasma C-peptide levels (P less than 0.01) and the presence of a 1.6 Kb insertion at the 5' end of the insulin gene. A gene dose-dependent effect was noted, class 3/3 individuals having the lowest after-load C-peptide concentration and class 1/3 an intermediate level (F for the linear trend: P = 0.007). This might suggest that insulin gene polymorphism affects insulin secretion in healthy individuals. In order to confirm this, a subgroup of six class 3/3 and eight class 1/1 individuals subsequently underwent a hyperglycaemic clamp. The tissue sensitivity to insulin was similar in the two groups but glucose-stimulated insulin secretion was markedly impaired in homozygotes for the class 3 allele. In this group, insulin secretion was, on average, only one-third of that in class 1/1 individuals (P less than 0.02). Similarly impaired in class 3/3 persons was the glucose + arginine-stimulated insulin secretion (P less than 0.05). We conclude that the polymorphism at the 5' end of the insulin gene is associated with variations in insulin secretion in healthy humans.     

Risk of pancreatic adverse events associated with the use of glucagon-like peptide-1 receptor agonist and dipeptidyl peptidase-4 inhibitor drugs: A systematic review and metaanalysis of randomized trials

AIM: To systematically assess risk of pancreatic adverse events with glucagon-like peptide-1(GLP-1) receptor agonist and dipeptidyl peptidase-4(DPP-4) inhibitor drugs.METHODS: We searched Pub Med, Embase, CINAHL, Cochrane review of clinical trials, pharmaceutical company clinical trials register, United States Food and Drug Administration website, European Medicines Agency website and Clinical Trials.gov for randomized controlled trials from inception to October 2013. Randomized control trial studies were selected for inclusion if they reported on pancreatic complication events and/or changes in pancreatic enzyme levels(serum amylase and serum lipase) as adverse events or as serious adverse events for patients who were on GLP-1 receptor agonist and DPP-4 inhibitor drugs. Two independent reviewers extracted data directly. We performed Peto odds ratio(OR) fixed effect meta-analysis of pancreatic adverse events a, and assessed heterogeneity with the I~2 statistic.RESULTS: Sixty-eight randomized controlled trials were eligible. A total of 60720 patients were included in our analysis of the association of risk of pancreatic complication events with GLP-1 agents. A total of 89 pancreatic related adverse events occurred among the GLP-1 agents compared to 74 events among the controls. There was a statistically significant increased risk of elevation of pancreatic enzymes associated with GLP-1 agents compared with control(Peto OR = 3.15, 95%CI: 1.56-6.39, P = 0.001, I2 = 0%). There was no statistically significant difference in the risk of pancreatic adverse event associated with GLP-1 agent compared with controls(Peto OR = 1.00, 95%CI: 0.73-1.37, P = 1.00, I2 = 0%). There were a total of 71 pancreatitis events in patients on GLP-1 agents and 56 pancreatitis events occurred in the control patients. There were 36 reports of pancreatic cancer in these studies. Of these cases, 2 used linagliptin, 2 used alogliptin, 1 used vildagliptin, 7 used saxagliptin while 6 used sitagliptin. The remaining 18 cases occurred among controls.CONCLUSION: Although GLP-1 based agents are associated with pancreatic enzyme elevation, we were unable to confirm a significant risk of pancreatitis or pancreatic cancer.     

Development of sandwich ELISAs for detecting glucagon-like peptide-1 secretion from intestinal L-cells and their application in STC-1 cells and mice

Certain nutrients stimulate glucagon-like peptide-1 (GLP-1) secretion from the intestinal enteroendocrine L-cells, but due to rapid degradation by the DPP-4 enzyme, >90% is converted to inactive metabolite before reaching the target organs via circulation. Plants are a source of potent bioactive compounds that promote endogenous secretion of GLP-1 from L-cells. To search for the effective bioactive compound from a vast library of natural compounds, a reliable and low-cost assay is required considering the high cost of commercial assays. We developed a low-cost sandwich enzyme-linked immunosorbent assays (s-ELISAs) for detecting ‘total’, ‘sensitive active’, and ‘wide-range active’ GLP-1. The s-ELISAs exhibited high sensitivity with measurement ranges between 0.94~240, 0.98~62.5, and 4.8~4,480 pmol/L, respectively. High precision was observed; i.e., CVs within 5% and 20% for intra- and inter-assay variations, respectively, and excellent recovery of exogenous GLP-1 from assay buffer. The developed s-ELISAs had the same performance as the commercial kits and approximately 80% cheaper cost. For their application, cinnamtannin A2-induced GLP-1 secretion was confirmed in STC-1 cells consistent with our previous findings. The s-ELISAs were further validated by measuring plasma GLP-1 level in mice after oral administration of black soy bean seed coat extract containing cinnamtannin A2.     

血清睾酮/促黄体生成素、促卵泡激素及促黄体生成素水平检测在诊断睾丸生精作用中的价值

目的观察血清睾酮(T)/促黄体生成素(LH)、促卵泡激素(FSH)、LH水平检测在临床睾丸生精作用诊断中的临床价值。方法选择2014年1月至2015年6月到佛山市顺德区龙江医院进行原发性不育检查的60例患者进行研究,并且选择同期来佛山市顺德区龙江医院进行体检的健康男性60例作为健康对照组,对所有研究对象进行T、FSH、LH水平检测,比较健康对照组和不孕组患者FSH、T/LH、LH水平,以及少精组、极度少精组、特发性无精组患者FSH、T/LH、LH水平,以及中度、重度和不可逆性睾丸生精障碍患者FSH、T/LH、LH水平。结果与健康对照组比较,不育组患者FSH、LH明显升高,而T/LH明显降低,差异有统计学意义(P0.05)。与少精组比较,重度生精障碍组与不可逆性生精障碍组患者FSH与LH明显升高,而T/LH明显降低。与极度少精组比较,特发性无精组患者FSH与LH明显升高,而T/LH明显降低。与中度生精障碍组比较,重度生精障碍组与不可逆性生精障碍组患者FSH与LH明显升高,而T/LH明显降低。与重度生精障碍组比较,不可逆性生精障碍组患者FSH与LH明显升高,而T/LH明显降低。上述各组数据差异均有统计学意义(P0.05)。结论 FSH、T/LH、LH水平在睾丸生精作用检测中具有重要的临床价值。     

胰高血糖素样肽-1改善非酒精性脂肪肝病作用机制的研究进展

非酒精性脂肪肝病（nonalcoholic fatty liver disease，NAFLD）与肥胖、胰岛素抵抗、2型糖尿病和血脂紊乱等密切相关。随着肥胖和糖尿病的发病率逐渐升高，NAFLD已成为全球最常见的慢性肝脏疾病。目前，NAFLD的主要治疗方法为改善生活方式、减轻体质量和应用降脂药物，尚缺乏特效的治疗药物。靶向胰高血糖素样肽-1（glucagon-like peptide-1，GLP-1）已被批准用于糖尿病和肥胖治疗，最近大量临床前和临床研究表明，GLP-1可通过多种机制缓解NAFLD。本文将GLP-1改善NAFLD的相关机制研究进展综述如下。     

No effect of calcitriol on insulin-mediated glucose uptake in healthy subjects

Administration of active vitamin D (calcitriol) improves insulin sensitivity in uraemic patients. These patients have subnormal plasma calcitriol concentrations in parallel with increased intact parathyroid hormone (PTH) concentrations. It is therefore unclear whether the improvement in insulin sensitivity results from a direct effect of calcitriol or from amelioration of secondary hyperparathyroidism. So far, no evidence has been presented that insulin sensitivity is specifically affected by calcitriol in healthy subjects. We investigated the effect of (supra)therapeutic doses of calcitriol on insulin sensitivity in healthy volunteers. In a double-blind parallel group design, 18 healthy male subjects received in random order either placebo or 1.5 μg of calcitriol per day by mouth for 7 days. Insulin-mediated glucose uptake, i.e. insulin sensitivity, was assessed using the euglycaemic clamp technique. Mean glucose disposal rate, i.e. M-value, was not significantly affected by placebo or calcitriol treatment (placebo: 7.1 ± 1.3 mg kg^?1 min^?1 before and 7.2 ± 1.5 mg kg^?1 min^?1 after treatment; calcitriol 7.0 ± 1.4 mg kg^?1 min^?1 and 7.2 ± 1.4 mg kg^?1 min^?1). There were no significant changes in mean plasma glucose, insulin, phosphate, bicarbonate and ionized calcium concentrations after administration of placebo or calcitriol. Furthermore, platelet intracellular calcium concentration (assessed by fluorescence spectroscopy) and mean arterial blood pressure (24 h ambulatory measurement) did not change with placebo and calcitriol treatment. On the other hand, mean intact PTH concentration decreased significantly (P < 0.01) with calcitriol treatment, but not with placebo. In addition, mean 24 h urinary calcium excretion increased significantly (P < 0.05) with calcitriol administration but was unchanged with placebo. Administration of (supra)physiological doses of calcitriol has no effect on insulin sensitivity in healthy subjects, despite a significant decrease in PTH concentrations. These observations are compatible with the notion that the effect of calcitriol on insulin sensitivity is present only in uraemic calcitriol-depleted patients.     

Effects of burn injury on insulin secretion and on sensitivity to insulin in the rat in vivo.

Both insulin resistance and impairment of insulin secretion are know to occur in man after injury. The relative importance of these effects was studied in rats 2 h after a non-lethal 20 percent dorsal scald. No impairment of insulin secretion was found after this injury. Concentrations of both blood glucose and plasma insulin were elevated in scalded rats. Scalded rats responded to intravenous glucose injection (1-0 g/kg) with a further rise in plasma insulin concentration, which remained normal for the prevailing blood glucose concentration. However, marked impairment of glucose tolerance was observed, indicating the presence of insulin resistance. After intravenous insulin injection (1-0 U/kg) the initial rate coefficient for fall of blood glucose concentration was significantly lower (p less than 0-02) in scalded (mean 3-9 percent min.(-1) than in control rats (mean 6-3 percent min.(-1). The minimum in blood glucose concentration after insulin injection was reached at 10 min. in control rats, but not until 60 min. after injection in scalded rats. This difference was due to a delay in compensation for the hypoglycaemia in the scalded rats, since the rate of disappearance of insulin measured by injection of a tracer of 125I-labelled bovine insulin was not decreased after this injury. It was concluded that the impairment of glucose utilization in scalded rats (Heath and Corney, 1973) is due to decreased sensitivity to insulin rather than to suppression of insulin release.     

Effect of hemipancreatectomy and of pancreatic diversion on the tolerance to a glucose load in humans

BACKGROUND: The role of the pattern, quantity and site of insulin secretion in the tolerance to a glucose challenge is not fully evaluated in humans because it is difficult to obtain appropriate clinical models. DESIGN: To address this issue, we studied subjects with reduced pancreatic mass (hemipancreatectomized, HEMI), systemic insulin delivery (pancreas transplant recipients, PTX), and two control groups (healthy, CON; and with uveitis on the same immunosuppression as PTX, UVE), with an hyperglycaemic clamp (study 1, + 4.2 mmol L-1), using a repeat experiment (study 2) with a fixed glucose infusion, calculated to increase by 35% that in study 1. RESULTS: In study 1, CON increased glucose uptake to 20 +/- 3 micromol kg-1 min-1 after a biphasic insulin response. In study 2, CON further increased the glucose uptake via an increment in prehepatic insulin secretion that stimulated insulin sensitivity without changes in peripheral insulin and glucose concentrations. HEMI and PTX had 35% less glucose uptake in study 1, compared to CON, and increased glucose concentrations (+ 1.6 mmol L-1) in study 2. UVE had an intermediate defect. The causes of intolerance were different: HEMI had a defective first-phase insulin secretion (50% peripheral insulin concentrations) but maintained insulin sensitivity; PTX had normal peripheral insulin but only one-third of the insulin sensitivity of CON. CONCLUSIONS: Hemipancreatectomy and systemic insulin delivery impair first-phase insulin secretion; second-phase peripheral insulinization (HEMI); insulin sensitivity (PTX); and a mechanism evidentiated in study 2 of CON that increases insulin sensitivity in response to prehepatic insulin secretion (both groups). Failure of these mechanisms is largely compensated by hyperglycaemia.