Insulin Secretion Predicts the Response to Antidiabetic Therapy in Patients With New-onset Diabetes.

CONTEXT: The results of the present study demonstrate that beta cell function in newly diagnosed T2DM patients is the key predictor of response to glucose lowering medications and provides a practical tool (C-Pep120 /C-Pep0) to guide the choice of glucose lowering agent. OBJECTIVE: This work aims to identify predictors for individualization of antidiabetic therapy in patients with new-onset type 2 diabetes mellitus (T2DM). METHODS: A total of 261 drug-naive participants in the Efficacy and Durability of Initial Combination Therapy for Type 2 Diabetes (EDICT) study, with new-onset diabetes, were randomly assigned in a single-center study to receive 1) metformin followed by glipizide and then insulin glargine on failure to achieve glycated hemoglobin A1c (HbA1c) less than 6.5%, or 2) initial triple therapy with metformin/pioglitazone/exenatide. Each patient received a 75-g oral glucose tolerance test (OGTT) prior to start of therapy. Factors that predicted response to therapy were identified using the area under the receiver operating characteristic curve method. RESULTS: Thirty-nine patients started and maintained the treatment goal (HbA1c < 6.5%) on metformin only, and did not require intensification of antihyperglycemic therapy; 54 patients required addition of glipizide to metformin; and 47 patients required insulin addition to metformin plus glipizide for glucose control. The plasma C-peptide concentration (C-Pep)120/C-Pep0 ratio during the OGTT was the strongest predictor of response to therapy. Patients with a ratio less than 1.78 were more likely to require insulin for glucose control, whereas patients with a ratio greater than 2.65 were more likely to achieve glucose control with metformin monotherapy. In patients started on initial triple therapy, the HbA1c decreased independently of the C-Pep120/C-Pep0 ratio. CONCLUSION: The increase in C-Pep above fasting following glucose load predicts the response to antihyperglycemic therapy in patients with new-onset diabetes. C-Pep120/C-Pep0 provides a useful tool for the individualization of antihyperglycemic therapy in patients with new-onset T2DM.

Revitalization of pioglitazone: the optimum agent to be combined with a sodium-glucose co-transporter-2 inhibitor.

The recently completed EMPA-REG study showed that empagliflozin significantly decreased the major adverse cardiac events (MACE) endpoint, which comprised cardiovascular death, non-fatal myocardial infarction (MI) and stroke, in patients with high-risk type 2 diabetes (T2DM), primarily through a reduction in cardiovascular death, without a significant decrease in either MI or stroke. In the PROactive study, pioglitazone decreased the MACE endpoint by a similar degree to that observed in the EMPA-REG study, through a marked reduction in both recurrent MI and stroke and a modest reduction in cardiovascular death. These observations suggest that pioglitazone might be an ideal agent to combine with empagliflozin to further reduce cardiovascular events in patients with high-risk diabetes as empagliflozin also promotes salt/water loss and would be expected to offset any fluid retention associated with pioglitazone therapy. In the present paper, we provide an overview of the potential benefits of combined pioglitazone/empagliflozin therapy to prevent cardiovascular events in patients with T2DM.

Initial combination therapy with metformin, pioglitazone and exenatide is more effective than sequential add-on therapy in subjects with new-onset diabetes. Results from the Efficacy and Durability of Initial Combination Therapy for Type 2 Diabetes (EDICT): a randomized trial.

AIM: To test our hypothesis that initiating therapy with a combination of agents known to improve insulin secretion and insulin sensitivity in subjects with new-onset diabetes would produce greater, more durable reduction in glycated haemoglobin (HbA1c) levels, while avoiding hypoglycaemia and weight gain, compared with sequential addition of agents that lower plasma glucose but do not correct established pathophysiological abnormalities. METHODS: Drug-naïve, recently diagnosed subjects with type 2 diabetes mellitus (T2DM) were randomized in an open-fashion design in a single-centre study to metformin/pioglitazone/exenatide (triple therapy; n = 106) or an escalating dose of metformin followed by sequential addition of sulfonylurea and glargine insulin (conventional therapy; n = 115) to maintain HbA1c levels at <6.5% for 2 years. RESULTS: Participants receiving triple therapy experienced a significantly greater reduction in HbA1c level than those receiving conventional therapy (5.95 vs. 6.50%; p < 0.001). Despite lower HbA1c values, participants receiving triple therapy experienced a 7.5-fold lower rate of hypoglycaemia compared with participants receiving conventional therapy. Participants receiving triple therapy experienced a mean weight loss of 1.2 kg versus a mean weight gain of 4.1 kg (p < 0.01) in those receiving conventional therapy. CONCLUSION: The results of this exploratory study show that combination therapy with metformin/pioglitazone/exenatide in patients with newly diagnosed T2DM is more effective and results in fewer hypoglycaemic events than sequential add-on therapy with metformin, sulfonylurea and then basal insulin.

Metabolites as novel biomarkers for childhood obesity-related traits in Mexican-American children.

BACKGROUND/OBJECTIVES: Although newer approaches have identified several metabolites associated with obesity, there is paucity of such information in paediatric populations, especially among Mexican-Americans (MAs) who are at high risk of obesity. Therefore, we performed a global serum metabolite screening in MA children to identify biomarkers of childhood obesity. METHODS: We selected 15 normal-weight, 13 overweight and 14 obese MA children (6-17 years) and performed global serum metabolite screening using ultra-performance liquid chromatography/quadruple orthogonal acceleration time of flight tandem micro mass spectrometer. Metabolite values were analysed to assess mean differences among groups using one-way analysis of variance, to test for linear trend across groups and to examine Pearson's correlations between them and seven cardiometabolic traits (CMTs): body mass index, waist circumference, systolic blood pressure, diastolic blood pressure, homeostasis model of assessment-insulin resistance, triglycerides and high-density lipoprotein cholesterol. RESULTS: We identified 14 metabolites exhibiting differences between groups as well as linear trend across groups with nominal statistical significance. After adjustment for multiple testing, mean differences and linear trends across groups remained significant (P < 5.9 × 10(-5) ) for L-thyronine, bradykinin and naringenin. Of the examined metabolite-CMT trait pairs, all metabolites except for 2-methylbutyroylcarnitine were nominally associated with two or more CMTs, some exhibiting significance even after accounting for multiple testing (P < 3.6 × 10(-3) ). CONCLUSIONS: To our knowledge, this study - albeit pilot in nature - is the first study to identify these metabolites as novel biomarkers of childhood obesity and its correlates. These findings signify the need for future systematic investigations of metabolic pathways underlying childhood obesity.

The effect of muraglitazar on adiponectin signalling, mitochondrial function and fat oxidation genes in human skeletal muscle in vivo.

AIMS: The molecular mechanisms by which muraglitazar (peroxisome proliferator-activated receptor γ/α agonist) improves insulin sensitivity in Type 2 diabetes mellitus are not fully understood. We hypothesized that muraglitazar would increase expression of 5'-monophosphate-activated protein kinase and genes involved in adiponectin signalling, free fatty acid oxidation and mitochondrial function in skeletal muscle. METHODS: Sixteen participants with Type 2 diabetes received muraglitazar, 5 mg/day (n = 12) or placebo (n = 4). Before and after 16 weeks, participants had vastus lateralis muscle biopsy followed by 180 min euglycaemic hyperinsulinaemic clamp. RESULTS: Muraglitazar increased plasma adiponectin (9.0 ± 1.1 to 17.8 ± 1.5 µg/ml, P < 0.05), while no significant change was observed with placebo. After 16 weeks with muraglitazar, fasting plasma glucose declined by 31%, fasting plasma insulin decreased by 44%, insulin-stimulated glucose disposal increased by 81%, HbA1c decreased by 21% and plasma triglyceride decreased by 39% (all P < 0.05). Muraglitazar increased mRNA levels of 5'-monophosphate-activated protein kinase, adiponectin receptor 1, adiponectin receptor 2, peroxisome proliferator-activated receptor gamma coactivator-1 alpha and multiple genes involved in mitochondrial function and fat oxidation. In the placebo group, there were no significant changes in expression of these genes. CONCLUSIONS: Muraglitazar increases plasma adiponectin, stimulates muscle 5'-monophosphate-activated protein kinase expression and increases expression of genes involved in adiponectin signalling, mitochondrial function and fat oxidation. These changes represent important cellular mechanisms by which dual peroxisome proliferator-activated receptor agonists improve skeletal muscle insulin sensitivity.

Lowering plasma glucose concentration by inhibiting renal sodium-glucose cotransport.

Maintaining normoglycaemia not only reduces the risk of diabetic microvascular complications but also corrects the metabolic abnormalities that contribute to the development and progression of hyperglycaemia, that is insulin resistance and beta-cell dysfunction. Progressive beta-cell failure, in addition to side effects associated with many current antidiabetic agents, for example hypoglycaemia and weight gain, presents major obstacles to the achievement of the recommended goal of glycaemic control in patients with type 2 diabetes mellitus (T2DM). Thus, novel effective therapies are needed for optimal glucose control in subjects with T2DM. Most recently, specific inhibitors of the renal sodium-glucose cotransporter 2 (SGLT2) have been developed to produce glucosuria and lower the plasma glucose concentration. Because of the iR unique mechanism of action, which is independent of insulin secretion and insulin action, these agents are effective in lowering the plasma glucose concentration in all stages of the disease and can be combined with all other antidiabetic agents. In this review, we will summarize the available data concerning the mechanism of action, efficacy and safety of this novel class of antidiabetic agents.

Localization of a major susceptibility locus influencing preterm birth.

Preterm birth (PTB) is a complex trait, but little is known regarding its major genetic determinants. The objective of this study is to localize genes that influence susceptibility to PTB in Mexican Americans (MAs), a minority population in the USA, using predominantly microfilmed birth certificate-based data obtained from the San Antonio Family Birth Weight Study. Only 1302 singleton births from 288 families with information on PTB and significant covariates were considered for genetic analysis. PTB is defined as a childbirth that occurs at <37 completed weeks of gestation, and the prevalence of PTB in this sample was 6.4%. An ∼10 cM genetic map was used to conduct a genome-wide linkage analysis using the program SOLAR. The heritability of PTB was high (h(2) ± SE: 0.75 ± 0.20) and significant (P = 4.5 × 10(-5)), after adjusting for the significant effects of birthweight and birth order. We found significant evidence for linkage of PTB (LOD = 3.6; nominal P = 2.3 × 10(-5); empirical P = 1.0 × 10(-5)) on chromosome 18q between markers D18S1364 and D18S541. Several other chromosomal regions (2q, 9p, 16q and 20q) were also potentially linked with PTB. A strong positional candidate gene in the 18q linked region is SERPINB2 or PAI-2, a member of the plasminogen activator system that is associated with various reproductive processes. In conclusion, to our knowledge, perhaps for the first time in MAs or US populations, we have localized a major susceptibility locus for PTB on chromosome 18q21.33-q23.

Effect of pioglitazone on body composition and bone density in subjects with prediabetes in the ACT NOW trial.

AIMS: This study examined the effects of pioglitazone on body weight and bone mineral density (BMD) prospectively in patients with impaired glucose tolerance as pioglitazone (TZD) increases body weight and body fat in diabetic patients and increases the risk of bone fractures. METHODS: A total of 71 men and 163 women aged 49.3 (10.7) years [mean (s.d.)]; body mass index (BMI), 34.5 (5.9) kg/m(2) were recruited at five sites for measurements of body composition by dual energy X-ray absorptiometry at baseline and at conversion to diabetes or study end, if they had not converted. RESULTS: Mean follow-up was 33.6 months in the pioglitazone group and 32.1 months in the placebo group. Body weight increased 4.63 ± 0.60 (m ± s.e.) kg in the pioglitazone group compared to 0.98 ± 0.62 kg in the PIO group (p < 0.0001). Body fat rose 4.89 ± 0.42 kg in the pioglitazone group compared to 1.41 ± 0.44 kg, (p < 0.0001) in placebo-treated subjects. The increase in fat was greater in legs and trunk than in the arms. BMD was higher in all regions in men and significantly so in most. PIO decreased BMD significantly in the pelvis in men and women, decreased BMD in the thoracic spine and ribs of women and the lumbar spine and legs of men. Bone mineral content also decreased significantly in arms, legs, trunk and in the total body. CONCLUSIONS: Pioglitazone increased peripheral fat more than truncal fat and decreased BMD in several regions of the body.

Insulin vs GLP-1 analogues in poorly controlled Type 2 diabetic subjects on oral therapy: a meta-analysis.

AIM: To compare insulin and GLP-1 analogues therapy on glycemic control in poorly controlled Type 2 diabetes (T2DM) subjects failing on oral therapy. METHODS: The electronic database PubMed was systematically searched for randomized controlled trial (RCT) with duration >16 weeks comparing the addition of insulin therapy vs glucagon-like peptide (GLP-1) analogues in poorly controlled T2DM subjects on oral therapy. RESULTS: We identified 7 RCT with 2199 patients of whom 1119 were assigned to insulin therapy and 1080 received a GLP-1 analogue. Both insulin and GLP-1 analogues were effective in lowering glycated hemoglobin (HbA(1c)) with no statistically significant difference between the mean decreases in HbA(1c). However, insulin was more effective than GLP-1 analogues in lowering the fasting plasma glucose concentration, while GLP-1 agonists were more effective in lowering the postprandial glucose concentration. Insulin therapy was associated with weight gain while GLP-1 analogues consistently caused weight loss and the difference between the mean change in body weight between the two therapies was highly statistically significant. Despite a similar decrease in HbA(1c), the risk of hypoglycemia was 35% lower (p=0.001) with GLP-1 therapy compared to insulin. Compared to insulin, GLP-1 analogues caused a significant decrease in systolic blood pressure and were associated with greater rate of gastrointestinal adverse events. CONCLUSION/INTERPRETATION: In poorly controlled T2DM subjects on oral therapy, GLP-1 analogues and insulin are equally effective in lowering the HbA(1c). However, GLP-1 analogues have additional non-glycemic benefits and lower risk of hypoglycemia. Thus, GLP-1 analogues should be considered as a treatment option in this group of diabetic individuals.

Impact of obesity severity and duration on pancreatic ß- and α-cell dynamics in normoglycemic non-human primates.

OBJECTIVE: Obesity is associated with high insulin and glucagon plasma levels. Enhanced ß-cell function and ß-cell expansion are responsible for insulin hypersecretion. It is unknown whether hyperglucagonemia is due to α-cell hypersecretion or to an increase in α-cell mass. In this study, we investigated the dynamics of the ß-cell and α-cell function and mass in pancreas of obese normoglycemic baboons. METHODS: Pancreatic ß- and α-cell volumes were measured in 51 normoglycemic baboons divided into six groups according to overweight severity or duration. Islets morphometric parameters were correlated to overweight and to diverse metabolic and laboratory parameters. RESULTS: Relative α-cell volume (RαV) and relative islet α-cell volume (RIαV) increased significantly with both overweight duration and severity. Conversely, in spite of the induction of insulin resistance, overweight produced only modest effects on relative ß-cell volume (RßV) and relative islet ß-cell volume (RIßV). Of note, RIßV did not increase neither with overweight duration nor with overweight severity, supposedly because of the concomitant, greater increase in RIαV. Baboons' body weights correlated with serum levels of interleukin-6 and tumor necrosis factor-α soluble receptors, demonstrating that overweight induces abnormal activation of the signaling of two cytokines known to impact differently ß- and α-cell viability and replication. CONCLUSION: In conclusion, overweight and insulin resistance induce in baboons a significant increase in α-cell volumes (RαV, RIαV), whereas have minimal effects on the ß cells. This study suggests that an increase in the α-cell mass may precede the loss of ß cells and the transition to overt hyperglycemia and diabetes.

Efficacy and tolerability of the DPP-4 inhibitor alogliptin combined with pioglitazone, in metformin-treated patients with type 2 diabetes.

CONTEXT: Optimal management of type 2 diabetes remains an elusive goal. Combination therapy addressing the core defects of impaired insulin secretion and insulin resistance shows promise in maintaining glycemic control. OBJECTIVE: The aim of the study was to assess the efficacy and tolerability of alogliptin combined with pioglitazone in metformin-treated type 2 diabetic patients. DESIGN, SETTING, AND PATIENTS: We conducted a multicenter, randomized, double-blind, placebo-controlled, parallel-arm study in patients with type 2 diabetes. INTERVENTIONS: The study consisted of 26-wk treatment with alogliptin (12.5 or 25 mg qd) alone or combined with pioglitazone (15, 30, or 45 mg qd) in 1554 patients on stable-dose metformin monotherapy (≥1500 mg) with inadequate glycemic control. MAIN OUTCOME MEASURE: The primary endpoint was change in glycosylated hemoglobin (HbA(1c)) from baseline to wk 26. Secondary endpoints included changes in fasting plasma glucose and ß-cell function. Primary analyses compared pioglitazone therapy [all doses pooled, pioglitazone alone (Pio alone); n = 387] with alogliptin 12.5 mg plus any dose of pioglitazone (A12.5+P; n = 390) or alogliptin 25 mg plus any dose of pioglitazone (A25+P; n = 390). RESULTS: When added to metformin, the least squares mean change (LSMΔ) from baseline HbA(1c) was -0.9 ± 0.05% in the Pio-alone group and -1.4 ± 0.05% in both the A12.5+P and A25+P groups (P < 0.001 for both comparisons). A12.5+P and A25+P produced greater reductions in fasting plasma glucose (LSMΔ = -2.5 ± 0.1 mmol/liter for both) than Pio alone (LSMΔ = -1.6 ± 0.1 mmol/liter; P < 0.001). A12.5+P and A25+P significantly improved measures of ß-cell function (proinsulin:insulin and homeostasis model assessment of ß-cell function) compared to Pio alone, but had no effect on homeostasis model assessment of insulin resistance. The LSMΔ body weight was 1.8 ± 0.2, 1.9 ± 0.2, and 1.5 ± 0.2 kg in A12.5+P, A25+P, and Pio-alone groups, respectively. Hypoglycemia was reported by 1.0, 1.5, and 2.1% of patients in the A12.5+P, A25+P, and Pio-alone groups, respectively. CONCLUSIONS: In type 2 diabetic patients inadequately controlled by metformin, the reduction in HbA(1c) by alogliptin and pioglitazone was additive. The decreases in HbA(1c) with A12.5+P and A25+P were similar. All treatments were well tolerated.

Lentivirus shRNA Grb10 targeting the pancreas induces apoptosis and improved glucose tolerance due to decreased plasma glucagon levels.

AIMS/HYPOTHESIS: The physiological significance of growth factor receptor-bound protein-10 (GRB10) in the pancreas is unclear. We hypothesised that GRB10 is involved in pancreatic apoptosis, as GRB10 binds with a family of cell-survival-related proteins implicated in apoptosis. METHODS: Lentiviral vector small hairpin RNA (shRNA) targeting Grb10 was injected in vivo via an intraductal pancreatic route to target pancreatic tissues in adult mice, which were studied 2 weeks post-injection. RESULTS: Using the TUNEL assay, we demonstrated for the first time that in vivo injection of lentivirus shRNA Grb10 directly into the adult mouse pancreas induced apoptosis in both exocrine and endocrine (alpha and beta) cells. This effect was more pronounced in alpha cells. Levels of the pro-apoptotic protein BCL2-interacting mediator of cell death (BIM) in islets was higher in lentivirus shRNA Grb10 than in lentivirus shRNA scramble mice. In the apoptotic pathway, BIM initiates apoptosis signalling, leading to activation of the caspase cascade. We propose that, when complexed with GRB10, BIM is inactive. On activation by stress signalling or, in the present study, following injection of lentivirus shRNA Grb10 into pancreas, BIM becomes unbound from GRB10 and activates the caspase cascade. Indeed, caspase-3 activity in islets was higher in the experimental than in the control group. Apoptosis induced by shRNA Grb10 resulted in a 34% decrease in fasting plasma glucagon. Mice injected with shRNA Grb10 had improved glucose tolerance despite reduced insulin secretion compared with shRNA scramble control mice. CONCLUSIONS/INTERPRETATION: GRB10 is critically involved in alpha cell survival and, as a result, plays an important role in regulating basal glucagon secretion and glucose tolerance in adult mice.

The role of the kidneys in glucose homeostasis: a new path towards normalizing glycaemia.

The maintenance of normal glucose homeostasis requires a complex, highly integrated interaction among the liver, muscle, adipocytes, pancreas and neuroendocrine system. Recent studies have showed that the kidneys also play a central role in glucose homeostasis by reabsorbing all the filtered glucose, an adaptive mechanism that ensures sufficient energy is available during fasting periods. This mechanism becomes maladaptive in diabetes, however, as hyperglycaemia augments the expression and activity of the sodium-glucose cotransporter (SGLT) 2 in the proximal tubule of the kidney. As a result, glucose reabsorption may be increased by as much as 20% in individuals with poorly controlled diabetes. SGLT2 is a low-affinity, high-capacity glucose transport protein that reabsorbs 90% of filtered glucose, while the high-affinity, low-capacity SGLT1 transporter reabsorbs the remaining 10%. SGLT2 represents a novel target for the treatment of diabetes. In animal studies, SGLT2 inhibition reduces plasma glucose levels, resulting in improved ß-cell function and enhanced insulin sensitivity in liver and muscle. Human studies have confirmed the efficacy of SLGT2 inhibitors in improving glucose control and reducing the A1c. Because the mechanism of SGLT2 inhibition is independent of circulating insulin levels or insulin sensitivity, these agents can be combined with all other antidiabetic classes, including exogenous insulin. Although the long-term efficacy and safety of SGLT2 inhibitors remain under study, the class represents a novel therapeutic approach with potential for the treatment of both type 2 and 1 diabetes.

Chromatin occupancy of transcription factor 7-like 2 (TCF7L2) and its role in hepatic glucose metabolism.

AIMS/HYPOTHESIS: The mechanisms by which transcription factor 7-like 2 (TCF7L2) regulates the pathways that are important in the pathogenesis of type 2 diabetes are unknown. We therefore examined the role of TCF7L2 in hepatic glucose production (HGP) in vitro and characterised the whole-genome chromatin occupancy of TCF7L2 in hepatocytes. METHODS: We investigated the effect of TCF7L2 silencing and overexpression on HGP from gluconeogenic precursors and used chromatin-immunoprecipitation (ChIP) combined with massively parallel DNA sequencing (ChIP-Seq) to investigate the DNA binding patterns of TCF7L2 across the whole genome. RESULTS: Silencing of TCF7L2 induced a marked increase in basal HGP, which was accompanied by significant increases in the expression of the gluconeogenic genes Fbp1, Pck1 and G6pc. Overexpression of Tcf7l2 reversed this phenotype and significantly reduced HGP. TCF7L2 silencing did not affect the half-maximal inhibitory concentration of insulin or metformin, but HGP remained elevated in TCF7L2-silenced cells due to the increased baseline HGP. Using ChIP-Seq, we detected 2,119 binding events across the genome. Pathway analysis demonstrated that diabetes genes were significantly over-represented in the dataset. Our results indicate that TCF7L2 binds directly to multiple genes that are important in regulation of glucose metabolism in the liver, including Pck1, Fbp1, Irs1, Irs2, Akt2, Adipor1, Pdk4 and Cpt1a. CONCLUSIONS/INTERPRETATION: TCF7L2 is an important regulator of HGP in vitro and binds directly to genes that are important in pathways of glucose metabolism in the liver. These data highlight the possibility that TCF7L2 may affect fasting and postprandial hyperglycaemia in carriers of at-risk TCF7L2 genetic polymorphisms.

Metabolic effects of muraglitazar in type 2 diabetic subjects.

AIM: To assess the effect of muraglitazar, a dual peroxisome proliferator-activated receptor (PPAR)γ-α agonist, versus placebo on metabolic parameters and body composition in subjects with type 2 diabetes mellitus (T2DM). METHODS: Twenty-seven T2DM subjects received oral glucose tolerance test (OGTT), euglycaemic insulin clamp with deuterated glucose, measurement of total body fat (DEXA), quantitation of muscle/liver (MRS) and abdominal subcutaneous and visceral (MRI) fat, and then were randomized to receive, in addition to diet, muraglitazar (MURA), 5 mg/day, or placebo (PLAC) for 4 months. RESULTS: HbA1c(c) decreased similarly (2.1%) during both MURA and PLAC treatments despite significant weight gain with MURA (+2.5 kg) and weight loss with PLAC (-0.7 kg). Plasma triglyceride, LDL cholesterol, free fatty acid (FFA), hsCRP levels all decreased with MURA while plasma adiponectin and HDL cholesterol increased (p < 0.05-0.001). Total body (muscle), hepatic and adipose tissue sensitivity to insulin and ß cell function all improved with MURA (p < 0.05-0.01). Intramyocellular, hepatic and abdominal visceral fat content decreased, while total body and subcutaneous abdominal fat increased with MURA (p < 0.05-0.01). CONCLUSIONS: Muraglitazar (i) improves glycaemic control by enhancing insulin sensitivity and ß cell function in T2DM subjects, (ii) improves multiple cardiovascular risk factors, (iii) reduces muscle, visceral and hepatic fat content in T2DM subjects. Despite similar reduction in A1c with PLAC/diet, insulin sensitivity and ß cell function did not improve significantly.

High-density lipoprotein-cholesterol and not HbA1c was directly related to cardiovascular outcome in PROactive.

AIM: In PROactive, pioglitazone reduced the incidence of death, myocardial infarction and stroke, and significantly improved HbA1c, systolic blood pressure (SBP), triglycerides and high-density lipoprotein (HDL)-cholesterol relative to placebo. As these glycaemic and lipid parameters are major cardiovascular (CV) risk factors, we assessed their separate contribution to the reduced incidence of CV outcomes. METHODS: Patients (n = 5238) with type 2 diabetes and macrovascular disease were randomized to 45 mg pioglitazone or placebo. Relationships among treatment, outcome (time to first event of all-cause mortality, myocardial infarction and stroke) and 10 laboratory measurements and vital signs were investigated using log-linear models. Continuous variable measurements (percent changes from baseline to average of all postbaseline values prior to censoring) were made discrete by categorizing into tertiles. Log-linear models were fitted to multiway tables of discrete data and analysis of deviance used to summarize sources of variation in the data. RESULTS: Although pioglitazone treatment was associated with a decrease in HbA1c and an increase in HDL-cholesterol (HDL-C), only the change from baseline HDL-C predicted the outcome (χ(2) = 28.89, p < 0.0001). No other variables, including HbA1c, triglycerides and systolic blood pressure, showed significant direct associations with outcome. When the analysis was extended to include baseline statin use, this was associated with an improved outcome independently of HDL-C changes. CONCLUSIONS: This post hoc analysis suggests that HDL-C, but probably not HbA1c, is a driver of pioglitazone's favourable influence on CV outcome.

Effect of exenatide on splanchnic and peripheral glucose metabolism in type 2 diabetic subjects.

OBJECTIVE: Our objective was to examine the mechanisms via which exenatide attenuates postprandial hyperglycemia in type 2 diabetes mellitus (T2DM). STUDY DESIGN: Seventeen T2DM patients (44 yr; seven females, 10 males; body mass index = 33.6 kg/m(2); glycosylated hemoglobin = 7.9%) received a mixed meal followed for 6 h with double-tracer technique ([1-(14)C]glucose orally; [3-(3)H]glucose i.v.) before and after 2 wk of exenatide. In protocol II (n = 5), but not in protocol I (n = 12), exenatide was given in the morning of the repeat meal. Total and oral glucose appearance rates (RaT and RaO, respectively), endogenous glucose production (EGP), splanchnic glucose uptake (75 g - RaO), and hepatic insulin resistance (basal EGP × fasting plasma insulin) were determined. RESULTS: After 2 wk of exenatide (protocol I), fasting plasma glucose decreased (from 10.2 to 7.6 mm) and mean postmeal plasma glucose decreased (from 13.2 to 11.3 mm) (P < 0.05); fasting and meal-stimulated plasma insulin and glucagon did not change significantly. After exenatide, basal EGP decreased (from 13.9 to 10.8 µmol/kg · min, P < 0.05), and hepatic insulin resistance declined (both P < 0.05). RaO, gastric emptying (acetaminophen area under the curve), and splanchnic glucose uptake did not change. In protocol II (exenatide given before repeat meal), fasting plasma glucose decreased (from 11.1 to 8.9 mm) and mean postmeal plasma glucose decreased (from 14.2 to 10.1 mm) (P < 0.05); fasting and meal-stimulated plasma insulin and glucagon did not change significantly. After exenatide, basal EGP decreased (from 13.4 to 10.7 µmol/kg · min, P = 0.05). RaT and RaO decreased markedly from 0-180 min after meal ingestion, consistent with exenatide's action to delay gastric emptying. CONCLUSIONS: Exenatide improves 1) fasting hyperglycemia by reducing basal EGP and 2) postmeal hyperglycemia by reducing the appearance of oral glucose in the systemic circulation.

Effects of insulin and oral anti-diabetic agents on glucose metabolism, vascular dysfunction and skeletal muscle inflammation in type 2 diabetic subjects.

BACKGROUND: To test potential differences between the actions of anti-diabetic medications, we examined the effects of oral hypoglycaemic agents versus glargine-apidra insulin therapy in T2DM. METHODS: T2DM subjects were randomized to either oral hypoglycaemic agents (pioglitazone, metformin and glipizide, n = 9) or insulin therapy (n = 12) for 6 months. Carotid intimal media thickness, vascular reactivity (flow-mediated vasodilatation; percent change in brachial artery basal diameter post-ischaemia) and sublingual nitrate were measured with ultrasonography. Euglycemic hyperinsulinemic (80 mU/m(2) ) clamp with [3]-3H-glucose and muscle biopsies were performed. RESULTS: Fasting plasma glucose (~257 to ~124 mg/dL, oral hypoglycaemic agents and ~256 to ~142 mg/dL, IT) and HbA(1c) (~10.3 to ~6.4%, OHA and ~10.7 to ~7.1%, IT) improved comparably. Endogenous glucose production (~2.1 to ~1.7 mg/kg/min, oral hypoglycaemic agents and ~2.3 to ~2.0 mg/kg/min, insulin therapy) and endogenous glucose production suppression by insulin (~0.4 to ~0.3 mg/kg min, oral hypoglycaemic agents and ~0.5 to ~0.7 mg/kg min, insulin therapy) were different. Total glucose disposal × 100 increased in the oral hypoglycaemic agents group (~5.2 to ~8.1; p = 0.03), but not in insulin therapy (~6.0 to ~5.4 mg/kg/min/µU/mL × 100). OHA reduced CIMT (~0.080 to ~0.068 cm; p < 0.05), whereas insulin therapy did not (~0.075 to ~0.072 cm). After sublingual nitrate, brachial artery basal diameter increased in the OHA group (~8.7 to ~18.2%), but not in insulin therapy (~11.2 to ~15.0%; p < 0.02). Except for plasma adiponectin (~7 to ~15, oral hypoglycaemic agents versus ~6 to ~10, IT), changes in inflammatory markers in the circulation and in muscle (IκBα, super-oxidase dismutase 2, monocyte-chemo-attractant protein 1, p-ERK and JNK) were equivalent. CONCLUSIONS: Oral hypoglycaemic agents and insulin therapy treated patients achieved adequate glycemic control and the effects on circulating and muscle inflammatory biomarkers were similar, but only oral hypoglycaemic agents improved insulin sensitivity, vascular function and carotid intimal media thickness. These findings in a small sample suggest that the use of oral hypoglycaemic agents provides additional benefits to patients with T2DM.

Relationship of baseline HbA1c and efficacy of current glucose-lowering therapies: a meta-analysis of randomized clinical trials.

AIMS: Baseline glycated haemoglobin (HbA(1c)) concentrations vary between clinical trials of glucose-lowering agents and this may affect interpretation of clinical efficacy. The objective of this study is to quantify the relationship between baseline HbA(1c) and reduction of HbA(1c) in clinical trials. METHODS: PubMed literature searches from 1991 to 2007. Randomized controlled studies with placebo-controlled or comparator arms [> or = 9 patients in the intent-to-treat (ITT) population] ranging in duration from 23 to 52 weeks, in which baseline and change in glycated haemoglobin (HbA(1c)) were reported. The relationship between baseline HbA(1c) and change in HbA(1c) was analysed by a weighted least-squared regression model accounting for ITT population and variance of HbA(1c) change. Fourteen per cent of independently abstracted studies met the selection criteria. RESULTS: Meta-analysis from 59 clinical trials (8479 patients) produced weighted R(2) of 0.35 (P < 0.0001) for the association of baseline HbA(1c) and absolute change in HbA(1c). Subanalysis of eight metformin clinical trials demonstrated a stronger association [weighted R(2) of 0.67 (P = 0.0130)]. Exclusion of metformin clinical trials from the overall meta-analysis (n = 51) yielded a weighted R(2) of 0.31 (P < 0.0001). Subanalyses of clinical trials of glucose-lowering therapies predominantly targeting fasting (n = 37) or postprandial (n = 22) blood glucose produced weighted R(2) values of 0.27 (P < 0.001) and 0.42 (P < 0.005), respectively. CONCLUSIONS: These data demonstrate a positive relationship between baseline HbA(1c) and the magnitude of HbA(1c) change across 10 categories of glucose-lowering therapies, irrespective of class or mode of action. These observations should be considered when assessing clinical efficacy of diabetes therapies derived from clinical trials.