Effect of pioglitazone compared with metformin on glycemic control and indicators of insulin sensitivity in recently diagnosed patients with type 2 diabetes

Perspectives on weight control in diabetes - Tirzepatide

Tirzepatide, a once-weekly glucose-dependent insulinotropic polypeptide (GIP)/glucagon-like peptide-1 (GLP-1) receptor agonist (GIP/GLP-1 RA) improves glycemic control. Besides improvement of glycemic control, tirzepatide treatment is associated with significantly more weight loss as compared to potent selective GLP-1 receptor agonists as well as other beneficial changes in cardio-metabolic parameters, such as reduced fat mass, blood pressure, improved insulin sensitivity, lipoprotein concentrations, and circulating metabolic profile in individuals with type 2 diabetes (T2D). Some of these changes are partially associated with weight reduction. We review here the putative mechanisms of GIP receptor agonism contributing to GLP-1 receptor agonism-induced weight loss and respective findings with GIP/GLP-1 RAs, including tirzepatide in T2D preclinical models and clinical studies. Subsequently, we summarize the clinical data on weight loss and related non-glycemic metabolic changes of tirzepatide in T2D. These findings suggest that the robust weight loss and associated changes are important contributors to the clinical profile of tirzepatide for the treatment of T2D diabetes and serve as the basis for further investigations including clinical outcomes.

Dual A1 and A2A adenosine receptor antagonists, methoxy substituted 2-benzylidene-1-indanone, suppresses intestinal postprandial glucose and attenuates hyperglycaemia in fructose-streptozotocin diabetic rats

BACKGROUND/AIM

Recent research suggests that adenosine receptors (ARs) influence many of the metabolic abnormalities associated with diabetes. A non-xanthine benzylidene indanone derivative 2-(3,4-dihydroxybenzylidene)-4-methoxy-2,3-dihydro-1 H-inden-1-one (2-BI), has shown to exhibit higher affinity at A₁/A_2A ARs compared to caffeine. Due to its structural similarity to caffeine, and the established antidiabetic effects of caffeine, the current study was initiated to explore the possible antidiabetic effect of 2-BI.

METHODS

The study was designed to assess the antidiabetic effects of several A₁ and/or A_2A AR antagonists, via intestinal glucose absorption and glucose-lowering effects in fructose-streptozotocin (STZ) induced diabetic rats. Six-week-old male Sprague-Dawley rats were induced with diabetes via fructose and streptozotocin. Rats were treated for 4 weeks with AR antagonists, metformin and pioglitazone, respectively. Non-fasting blood glucose (NFBG) was determined weekly and the oral glucose tolerance test (OGTT) was conducted at the end of the intervention period.

RESULTS

Dual A₁/A_2A AR antagonists (caffeine and 2-BI) decreased glucose absorption in the intestinal membrane significantly (p < 0.01), while the selective A_2A AR antagonist (Istradefylline), showed the highest significant (p < 0.001) reduction in intestinal glucose absorption. The selective A₁ antagonist (DPCPX) had the least significant (p < 0.05) reduction in glucose absorption. Similarly, dual A₁/A_2A AR antagonists and selective A_2A AR antagonists significantly reduced non-fast blood glucose and improved glucose tolerance in diabetic rats from the first week of the treatment. Conversely, the selective A₁ AR antagonist did not reduce non-fast blood glucose significantly until the 4th week of treatment. 2-BI, caffeine and istradefylline compared well with standard antidiabetic treatments, metformin and pioglitazone, and in some cases performed even better.

CONCLUSION

2-BI exhibited good antidiabetic activity by reducing intestinal postprandial glucose absorption and improving glucose tolerance in a diabetic animal model. The dual antagonism of A₁/A_2A ARs presents a positive synergism that could provide a new possibility for the treatment of diabetes.

A Systematic Review and Meta-Analysis of Randomized Controlled Trials Comparing the Effects of Biguanides (Metformin) and Thiazolidinediones on Glucose Tolerance and Insulin Sensitivity in Patients With Type II Diabetes Mellitus

Type II diabetes mellitus (T2DM) is a global epidemic affecting people of all ages in developed and developing countries. The disease is usually characterized by insulin resistance and glucose intolerance; therefore, oral antidiabetic drugs such as thiazolidinediones (TZDs) and biguanide metformin are used to counter these defects. Due to the varied action mechanisms of TZDs and Metformin, their effects on insulin sensitivity and glucose tolerance may differ. Therefore, the current study was carried out to compare the effects of Metformin and TZDs on insulin sensitivity and glucose tolerance among patients with T2DM. Two methods, including using a well-outlined search strategy in 5 electronic databases including ScienceDirect, Google Scholar, PubMed, Scopus, and Embase, and a manual search which involved going through the reference lists of studies from the electronic databases were used to retrieve studies published between 2000 and 2022. Additionally, data analysis of outcomes retrieved from the studies eligible for inclusion and the methodological quality was carried out using the Review Manager software (RevMan 5.4.1) and STATA. The meta-analysis has shown that TZDs have a significantly better overall effect on fasting plasma glucose (FPG) (SMD:0.61; 95% CI:0.06, 1.16: p = 0.03) and insulin sensitivity than Metformin (Mean QUICKI: 0.306 ± 0.019 vs. 0.316 ± 0.019, respectively; p=0.0003). However, the TZDs and Metformin offer the same effect on glycemic control as assessed using HBA1c levels (MD: 0.10; 95% CI: -0.20, 0.40; p = 0.52). TZDs offer better insulin sensitivity and glucose tolerance improvements compared to Metformin. This evidence contradicts the current guidelines by the American Diabetes Association/European Association for the Study of Diabetes (ADA/EASD) and the American Association of Clinical Endocrinologists/American College of Endocrinology (AACE/ACE), which recommend the use of Metformin as the first-line drug monotherapy for patients with T2DM.

Pioglitazone use increases risk of Alzheimer's disease in patients with type 2 diabetes receiving insulin

Pioglitazone is an insulin resistance inhibitor widely used as monotherapy or combined with metformin or insulin in treating type 2 diabetes mellitus (T2DM). This study further investigated the relationship between pioglitazone use and the risk of developing Alzheimer's disease (AD) in patients newly diagnosed with T2DM, and examined the potential impact of insulin use on this association. Data were extracted from the National Health Insurance Research Database (NHIRD) of Taiwan. Our data exhibited that the risk of developing AD in the pioglitazone group was 1.584-fold (aHR = 1.584, 95% CI 1.203-1.967, p < 0.05) higher than that in the non-pioglitazone controls. Compared to patients without both insulin and pioglitazone, higher cumulative risk of developing AD was found in patients receiving both insulin and pioglitazone (aHR = 2.004, 95% CI = 1.702-2.498), pioglitazone alone (aHR = 1.596, 95% CI = 1.398-1.803), and insulin alone (aHR = 1.365, 95% CI = 1.125-1.572), respectively (all p < 0.05). A similar observation also found in the evaluation the use of diabetic drugs with a cumulative defined daily dose (cDDD). No interaction between pioglitazone and major risk factors (comorbidities) of AD was observed. In conclusion, alternative drug therapies may be an effective strategy for reducing risk of developing AD in T2DM patients.

Novel thiazolidinedione analog reduces a negative impact on bone and mesenchymal stem cell properties in obese mice compared to classical thiazolidinediones

Objective

The use of thiazolidinediones (TZDs) as insulin sensitizers has been shown to have side effects including increased accumulation of bone marrow adipocytes (BMAds) associated with a higher fracture risk and bone loss. A novel TZD analog MSDC-0602K with low affinity to PPARγ has been developed to reduce adverse effects of TZD therapy. However, the effect of MSDC-0602K on bone phenotype and bone marrow mesenchymal stem cells (BM-MSCs) in relation to obesity has not been intensively studied yet.

Methods

Here, we investigated whether 8-week treatment with MSDC-0602K has a less detrimental effect on bone loss and BM-MSC properties in obese mice in comparison to first generation of TZDs, pioglitazone. Bone parameters (bone microstructure, bone marrow adiposity, bone strength) were examined by μCT and 3-point bending test. Primary BM-MSCs were isolated and measured for osteoblast and adipocyte differentiation. Cellular senescence, bioenergetic profiling, nutrient consumption and insulin signaling were also determined.

Results

The findings demonstrate that MSDC-0602K improved bone parameters along with increased proportion of smaller BMAds in tibia of obese mice when compared to pioglitazone. Further, primary BM-MSCs isolated from treated mice and human BM-MSCs revealed decreased adipocyte and higher osteoblast differentiation accompanied with less inflammatory and senescent phenotype induced by MSDC-0602K vs. pioglitazone. These changes were further reflected by increased glycolytic activity differently affecting glutamine and glucose cellular metabolism in MSDC-0602K-treated cells compared to pioglitazone, associated with higher osteogenesis.

Conclusion

Our study provides novel insights into the action of MSDC-0602K in obese mice, characterized by the absence of detrimental effects on bone quality and BM-MSC metabolism when compared to classical TZDs and thus suggesting a potential therapeutical use of MSDC-0602K in both metabolic and bone diseases.

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MSDC-0602K improves bone quality and increases proportion of smaller BMAds in obese mice.

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MSDC-0602K-treated mice show lower adipogenic differentiation with less senescent phenotype in primary BM-MSCs.

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MSDC-0602K induces higher glycolytic activity in BM-MSCs compared to pioglitazone.

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MSDC-0602-treated BM-MSCs prefer glutamine over glucose uptake in comparison to AT-MSCs.

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Beneficial effect of MSDC-06002K in BM-MSCs manifests by absence of MPC inhibition.

Special Issue: Emerging Paradigms in Insulin Resistance

This Biomedicines Special Issue was designed to attract articles that focused on different facets of biology relating to insulin resistance, defined as reduced cellular and organismal response to the insulin hormone, and its underlying mechanisms [...]

Efficacy and Safety of Pioglitazone Monotherapy in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Pioglitazone, the only thiazolidinedione drug in clinical practice is under scrutiny due to reported adverse effects, it's unique insulin sensitising action provides rationale to remain as a therapeutic option for managing type 2 diabetes mellitus (T2DM). We conducted a systematic review and meta-analysis comparing pioglitazone monotherapy with monotherapies of other oral antidiabetic drugs for assessing its efficacy and safety in T2DM patients. Mean changes in glycated haemoglobin (HbA1c), and mean changes in fasting blood sugar (FBS) level, body weight (BW) and homeostasis model assessment-insulin resistance (HOMA-IR) were primary and secondary outcomes, respectively. Safety outcomes were changes in lipid parameters, blood pressure and incidences of adverse events. Metafor package of R software and RevMan software based on random-effects model were used for analyses. We included 16 randomised controlled trials. Pioglitazone monotherapy showed equivalent efficacy as comparators in reducing HbA1c by 0.05% (95% CI: -0.21 to 0.11) and greater efficacy in reducing FBS level by 0.24 mmol/l (95% CI: -0.48 to -0.01). Pioglitazone showed similar efficacy as comparators in reducing HOMA-IR (WMD: 0.05, 95% CI: -0.49 to 0.59) and increasing high-density lipoprotein level (WMD: 0.02 mmol/l, 95% CI: -0.06 to 0.10). Improved blood pressure (WMD: -1.05 mmHg, 95% CI: -4.29 to 2.19) and triglycerides level (WMD: -0.71 mmol/l, 95% CI: -1.70 to 0.28) were also observed with pioglitazone monotherapy. There was a significant association of pioglitazone with increased BW (WMD: 2.06 kg, 95% CI: 1.11 to 3.01) and risk of oedema (RR: 2.21, 95% CI: 1.48 to 3.31), though the risk of hypoglycaemia was absolutely lower (RR: 0.51, 95% CI: 0.33 to 0.80). Meta-analysis supported pioglitazone as an effective treatment option for T2DM patients to ameliorate hyperglycaemia, adverse lipid metabolism and blood pressure. Pioglitazone is suggested to prescribe following individual patient's needs. It can be a choice of drug for insulin resistant T2DM patients having dyslipidaemia, hypertension or history of cardiovascular disease.

Comparison of Pioglitazone and Metformin Efficacy against Glucocorticoid Induced Atherosclerosis and Hepatic Steatosis in Insulin Resistant Rats

INTRODUCTION

Insulin Resistance is a major cause of Atherosclerosis (AS) and Non Alcoholic Fatty Liver Disease (NAFLD). These lipid alterations in blood vessels and liver may progress to cardiovascular abnormalities and cirrhosis respectively. Drugs like pioglitazone (PIO) and metformin (MET) are effective insulin sensitizers used in T2DM. But their efficacy and tolerability needs to be compared in IR associated abnormalities.

AIM

To compare the efficacy of PIO and MET in glucocorticoid induced AS, Hepatic Steatosis (HS) and IR in albino rats.

MATERIALS AND METHODS

Male Wistar albino rats were randomized into four groups (n=6). Group 1 (Normal control) rats consumed 2% gum acacia orally for 12 days. Group 2 {dexamethasone (DEX) control} rats were administered 2% gum acacia orally for 12 days and DEX (8 mg/kg) intraperitoneally (i.p.) from 7th to 12th day during the study period. Group 3 and 4 (PIO and MET control) rats received oral administration of PIO (45 mg/kg) and MET (1000 mg/kg) for 12 days respectively. Both groups were treated with DEX (8 mg/kg/i.p.) from 7th to 12th day during the study period. On last day, fasting blood was collected and rats were sacrificed by cervical dislocation; aorta and liver tissues were isolated for the histopathological examination. Body weight, liver weight and liver volume were measured. Blood samples were processed for biochemical parameters. The data were analysed by One-way Analysis of variance (ANOVA) followed by Scheffe's multiple comparison post-hoc test. The statistical significance was assumed at p<0.05.

RESULTS

Our results established the possible role of DEX in the development of AS and HS. Histopathological examination of Group 2 rats treated with DEX showed a marked lipid accumulation in the aorta and liver. Administration of MET and PIO resulted in partial to complete restoration of DEX induced fatty changes in aorta and liver. Both drugs significantly (p<0.05) prevented the elevation of insulin, lipid, glucose levels, liver weight and liver volume in DEX treated rats. They had significantly (p<0.05) improved body weight and insulin sensitivity. However, PIO was highly significant (p<0.05) compared to MET in reducing DEX induced IR complications.

CONCLUSION

These findings suggest that PIO was more effective insulin sensitizer compared to MET in reducing AS, HS and IR induced by glucocorticoids.

Pioglitazone — an oral antidiabetic agent and metabolic syndrome modulator. Can theory translate into practice?

The metabolic syndrome, associated with insulin resistance, is a cluster of cardiovascular risk factors which results in premature morbidity and mortality from atherosclerotic vascular disease. Pioglitazone, a peroxisome-proliferator-activated receptor gamma (PPARγ) agonist, is an insulin sensitiser with the ability to address key features of the metabolic syndrome: glucose intolerance including type 2 diabetes, hypertension, dyslipidaemia, the pro-coagulant state, endothelial dysfunction, inflammation and atherosclerosis. The greatest potential benefit of pioglitazone is to influence atherogenesis itself through its pleiotrophic effects on vascular risk factors. This has been tested by the PROactive study, results of which are published in September 2005.

Fenofibrate plus Metformin Produces Cardioprotection in a Type 2 Diabetes and Acute Myocardial Infarction Model

We investigated whether fenofibrate, metformin, and their combination generate cardioprotection in a rat model of type 2 diabetes (T2D) and acute myocardial infarction (AMI). Streptozotocin-induced diabetic- (DB-) rats received 14 days of either vehicle, fenofibrate, metformin, or their combination and immediately after underwent myocardial ischemia/reperfusion (I/R). Fenofibrate plus metformin generated cardioprotection in a DBI/R model, reported as decreased coronary vascular resistance, compared to DBI/R-Vehicle, smaller infarct size, and increased cardiac work. The subchronic treatment with fenofibrate plus metformin increased, compared with DBI/R-Vehicle, total antioxidant capacity, manganese-dependent superoxide dismutase activity (MnSOD), guanosine triphosphate cyclohydrolase I (GTPCH-I) expression, tetrahydrobiopterin : dihydrobiopterin (BH₄ : BH₂) ratio, endothelial nitric oxide synthase (eNOS) activity, nitric oxide (NO) bioavailability, and decreased inducible NOS (iNOS) activity. These findings suggest that PPARα activation by fenofibrate + metformin, at low doses, generates cardioprotection in a rat model of T2D and AMI and may represent a novel treatment strategy to limit I/R injury in patients with T2D.

Insulin combined with Chinese medicine improves glycemic outcome through multiple pathways in patients with type 2 diabetes mellitus

Introduction/Aims

Insufficient insulin secretion or inefficient insulin response are responsible for the clinical outcome of type 2 diabetes mellitus. Administration of insulin alone is prone to cause secondary effects, resulting in an unsatisfactory outcome. Shen-Qi-Formula (SQF), a well-known Chinese medicinal formula, has been used for diabetic treatment for a long time. The present study was designed to investigate whether SQF in combination with insulin improved the clinical outcome of type 2 diabetes mellitus, and what mechanisms were possibly involved in the treatment.

Materials and Methods

A total of 219 patients were included in the study. Of these, 110 patients were treated with insulin monotherapy, and 109 with the combination therapy of SQF and insulin. Before and after 12-week treatment, the fasting blood glucose, postprandial blood glucose, β-cell function, insulin resistance and blood lipids were measured.

Results

The 12 weeks of SQF treatment in combination with insulin significantly decreased the fasting and postprandial blood glucose levels. Insulin secretion was not increased after the treatment, but β-cell function and insulin resistance were obviously improved. Furthermore, 12 weeks of treatment with SQF and insulin improved the levels of glucagon-like peptide-1, oxidative stress, blood lipids, coagulation function and bodyweight.

Conclusion

The results from our study showed that the combination therapy of SQF and insulin significantly improved the clinical outcome of type 2 diabetes mellitus compared with insulin monotherapy. The mechanism of improvement was possibly involved in the multiple pathways.

The effect of pioglitazone on weight, lipid profile and liver enzymes in type 2 diabetic patients

BACKGROUND

Pioglitazone is one of the antidiabetic agents used in the management of type 2 diabetes mellitus (DM). The effect of pioglitazone on blood glucose, lipid profile, liver enzymes and weight has been shown with conflicting results. In this study we aim to evaluate the effect of pioglitazone on the weight, lipid profile and liver enzymes in patients with DM.

METHODS

In this single-arm clinical trial, 110 poorly controlled diabetic type 2 patients (63.6% female with mean age of 54.26 ± 8.96 years) who were on maximal dosage of metformin and glibenclamide were enrolled. Patients were treated with pioglitazone for 3 months and laboratory. Fasting blood sugar (FBS), haemoglobin A1C (HbA1C), cholesterol, triglyceride, low-density lipoprotein (LDL) and high-density lipoprotein (HDL), alkaline phosphatase (ALK-P), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and weight changes were measured before and at the end of the study.

RESULTS

The levels of FBS (p < 0.001), HbA1c (p < 0.001), triglyceride (p = 0.001), ALT (p = 0.005) and ALK-P (p = 0.001) were significantly decreased, but weight was significantly increased (p < 0.001) after the intervention. There were no significant difference in cholesterol, LDL and HDL values before and after study.

CONCLUSION

Although pioglitazone causes a significant decrease in FBS, HbA1C and triglyceride levels, it is associated with weight gain, which would limit its utility. IRCT registration code: IRCT201209276712N2.

Can a selective PPARγ modulator improve glycemic control in patients with type 2 diabetes with fewer side effects compared with pioglitazone?

OBJECTIVE

INT131 besylate is a potent, nonthiazolidinedione, selective peroxisome proliferator-activated receptor γ (PPARγ) modulator (SPPARM) designed to improve glucose metabolism while minimizing the side effects of full PPARγ agonists. This placebo-controlled study compared the efficacy and side effects of INT131 besylate versus 45 mg pioglitazone HCl in subjects with type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

This was a 24-week randomized, double-blind, placebo- and active-controlled study of 0.5-3.0 mg INT131 versus 45 mg pioglitazone or placebo daily in 367 subjects with T2D on sulfonylurea or sulfonylurea plus metformin. The primary efficacy analysis was the comparison of change from baseline to week 24 in hemoglobin A1c (HbA1c) across treatment groups. Fluid status was assessed with a prospective scoring system for lower-extremity pitting edema.

RESULTS

INT131 had a steep dose response for efficacy as measured by changes in HbA1c. After 24 weeks' treatment, the 0.5-mg dose demonstrated minimal efficacy (HbA1c -0.3 ± 0.12%) and the 2-mg dose demonstrated near-maximal efficacy (HbA1c -1.1 ± 0.12%), which was not statistically different from the efficacy of 45 mg pioglitazone (HbA1c -0.9 ± 0.12%; P < 0.01 for noninferiority). With the 1-mg dose, INT131 provided significant improvements in glycemic control (HbA1c 0.8 ± 0.12; P < 0.001 vs. placebo) but with less edema, weight gain, and hemodilution than observed with 45 mg pioglitazone.

CONCLUSIONS

INT131 demonstrated dose-dependent reductions in HbA1c, equivalent to 45 mg pioglitazone, but with less fluid accumulation and weight gain, consistent with its SPPARM design.

Sitagliptin added to treatment with ongoing pioglitazone for up to 52 weeks improves glycemic control in Japanese patients with type 2 diabetes

Aims/Introduction:  Patients with type 2 diabetes mellitus often require treatment with more than one oral antihyperglycemic agent to achieve their glycemic goal. The present study was carried out to assess the efficacy and safety of sitagliptin as add‐on therapy in Japanese patients with type 2 diabetes mellitus inadequately controlled (HbA1c ≥ 6.9% and <10.4%) on pioglitazone monotherapy (15–45 mg/day).

Materials and Methods:  In the initial 12‐week, double‐blind treatment period, patients were randomized (1:1) to sitagliptin 50 mg/day (n = 66) or placebo (n = 68), followed by a 40‐week open‐label treatment period in which all patients received sitagliptin 50 mg/day that could have been increased to 100 mg/day for patients meeting predefined glycemic parameters.

Results:  After 12 weeks, mean changes from baseline in HbA1c (the primary end‐point), fasting plasma glucose and 2‐h post‐meal glucose were −0.8%, −0.9 mmol/L and −2.7 mmol/L, respectively, in the sitagliptin group compared with placebo (all P < 0.001). The incidence of adverse experiences during the double‐blind treatment period was similar in both treatment groups, and the incidences of hypoglycemia and gastrointestinal adverse experiences were low. In the open‐label period, improvements in glycemic parameters with sitagliptin treatment were maintained and sitagliptin was generally well tolerated.

Conclusions:  Sitagliptin as add‐on therapy provided significant improvements in glycemic parameters and was well tolerated in Japanese patients with type 2 diabetes mellitus inadequately controlled on pioglitazone monotherapy. This trial was registered with ClinicalTrials.gov (no. NCT00372060). (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00120.x, 2011)

Effects of replacing metformin with pioglitazone on glycemic control in japanese patients with poorly controlled type 2 diabetes mellitus: A 12-week, open-label, prospective study

BACKGROUND

Insulin resistance is a critical aspect of the pathophysiology of type 2 diabetes mellitus and is also associated with other risk factors for cardiovascular disease (eg, dyslipidemia and hypertension). Accordingly, insulin resistance is a possible target for lowering plasma glucose concentration and preventing diabetic macroangiopathy. Biguanides, such as metformin, and thiazolidinediones (TZDs), such as pioglitazone, improve insulin resistance.

OBJECTIVES

The aims of this study were to assess the effects of replacing a biguanide with a TZD on glycemic control in patients with poorly controlled type 2 diabetes mellitus, and also to identify the factors affecting interpatient variation in the effects of treatment change.

METHODS

This was a 12-week, open-label, prospective study in which previously prescribed metformin (500 or 750 mg/d) was replaced with pioglitazone (15 or 30 mg/d) in patients with poorly controlled type 2 diabetes mellitus. Patients with a glycosylated hemoglobin (HbA1c) concentration >7% despite treatment with diet, exercise, and hypoglycemic agents other than TZDs were eligible for the study. Patients who never received TZDs were also eligible for inclusion. Vital signs, metabolic parameters, and arterial stiffness were assessed at baseline and after 12 weeks of treatment with pioglitazone. The primary end point was change in HbA1c concentration after replacing metformin with pioglitazone. Tolerability was assessed by medical history, physical examination, and laboratory tests (aspartate aminotransferase, alanine aminotransferase, and γ-glutamyl transpeptidase).

RESULTS

Twenty-one Japanese patients (15 women, 6 men; mean [SD] age, 61.8 [8.4] years; body mass index, 25.5 [3.0] kg/m(2)) were included in the study. HbA1c concentration was not significantly changed from baseline after 12 weeks of pioglitazone treatment (8.0% [0.7%] vs 8.2% [0.7%]). Fasting plasma glucose (FPG) concentration also was not significantly changed after the replacement of treatment (156 [27] vs 144 [30] mg/dL). In addition, the resistin concentration did not change significantly from baseline after 12 weeks of pioglitazone treatment (6.6 [3.8] vs 6.4 [3.6] ng/mL). In contrast, significant improvement from baseline was observed in triglyceride (TG) concentrations (157 [109] vs 117 [68] mg/dL; P = 0.003), high-density lipoprotein cholesterol (HDL-C) (55 [12] vs 61 [16] mg/dL; P = 0.016), remnant-like particle cholesterol (6.6 [6.0] vs 5.3 [3.5] mg/dL; P = 0.048), and serum adiponectin (8.8 [4.3] vs 23.3 [11.7] μg/mL; P < 0.001). Pulse wave velocity was also significantly improved (1730 [361] vs 1622 [339] m/sec; P = 0.009). Changes in HbA1c were significantly correlated with serum fasting insulin concentration at baseline in the patients not receiving insulin preparations (r = -0.635, P = 0.013). The percentage change in serum adiponectin concentration was correlated with the percentage changes in HbA1c and FPG concentrations (HbA1c, r = -0.518, P = 0.019; FPG, r = -0.594, P = 0.006). Body weight was significantly increased after treatment (62.6 [11.9] vs 65.5 [12.2] kg; P < 0.001). Mild edema was reported in 5 patients. One patient discontinued treatment due to an increase in serum creatine kinase activity to ~6.6 times the upper limit of normal.

CONCLUSIONS

Replacement of metformin with pioglitazone did not produce significant differences in HbA1c and FPG concentrations from baseline after 12 weeks of treatment in these patients with poorly controlled type 2 diabetes mellitus. However, the replacement was effective in a subset of patients whose serum insulin concentrations were high or whose serum adiponectin concentrations were sensitive to TZDs. In addition, the replacement was associated with significant improvements in TG, HDL-C, serum adiponectin concentration, pulse wave velocity, and body weight increase from baseline.

Drug treatment of type 2 diabetes mellitus in patients for whom metformin is contraindicated

Metformin is considered an initial drug of choice for type 2 diabetes mellitus by leading recommendations. When contraindications to its use exist or patients cannot tolerate it due to adverse effects, clinicians have a variety of other classes of agents to treat hyperglycemia associated with type 2 diabetes mellitus. Each class of agent has its own benefit and safety profile. There are numerous factors to consider when selecting another agent in lieu of metformin including, but not limited to, overall efficacy in A1c reduction, adverse effect profile, cost, and patient preference. The number of factors influencing the decision process presents challenges and often no one specific agent is ideal. Each pharmacotherapeutic class of agents alternative to metformin for the treatment of hyperglycemia in type 2 diabetes mellitus as initial monotherapy is reviewed.

Pioglitazone: an antidiabetic drug with cardiovascular therapeutic effects

The antidiabetic compound pioglitazone, an activator of the intracellular peroxisome proliferator-activated receptor-gamma, and decreases metabolic and vascular insulin resistance. The drug is well tolerated, and its metabolic effects include improvements in blood glucose and lipid control. Vascular effects consist of improvements in endothelial function and hypertension, and a reduction in surrogate markers of artherosclerosis. In a large, placebo-controlled, outcome study in secondary prevention, PROactive study, the use of pioglitazone in addition to an existing optimized macrovascular risk management resulted in a significant reduction of macrovascular endpoints within a short observation period that was comparable to the effect of statins and angiotensin converting enzyme inhibitors in other trials. These results underline the value of pioglitazone for managing the increased cardiovascular risk of patients with a metabolic syndrome or Type 2 diabetes mellitus.

Metformin for weight loss and metabolic control in overweight outpatients with schizophrenia and schizoaffective disorder

OBJECTIVE

The purpose of this study was to determine whether metformin promotes weight loss in overweight outpatients with chronic schizophrenia or schizoaffective disorder.

METHOD

In a double-blind study, 148 clinically stable, overweight (body mass index [BMI] ≥27) outpatients with chronic schizophrenia or schizoaffective disorder were randomly assigned to receive 16 weeks of metformin or placebo. Metformin was titrated up to 1,000 mg twice daily, as tolerated. All patients continued to receive their prestudy medications, and all received weekly diet and exercise counseling. The primary outcome measure was change in body weight from baseline to week 16.

RESULTS

Fifty-eight (77.3%) patients who received metformin and 58 (81.7%) who received placebo completed 16 weeks of treatment. Mean change in body weight was -3.0 kg (95% CI=-4.0 to -2.0) for the metformin group and -1.0 kg (95% CI=-2.0 to 0.0) for the placebo group, with a between-group difference of -2.0 kg (95% CI=-3.4 to -0.6). Metformin also demonstrated a significant between-group advantage for BMI (-0.7; 95% CI=-1.1 to -0.2), triglyceride level (-20.2 mg/dL; 95% CI=-39.2 to -1.3), and hemoglobin A1c level (-0.07%; 95% CI=-0.14 to -0.004). Metformin-associated side effects were mostly gastrointestinal and generally transient, and they rarely led to treatment discontinuation.

CONCLUSIONS

Metformin was modestly effective in reducing weight and other risk factors for cardiovascular disease in clinically stable, overweight outpatients with chronic schizophrenia or schizoaffective disorder over 16 weeks. A significant time-by-treatment interaction suggests that benefits of metformin may continue to accrue with longer treatment. Metformin may have an important role in diminishing the adverse consequences of obesity and metabolic impairments in patients with schizophrenia.

Changes in body mass index following newly diagnosed type 2 diabetes and risk of cardiovascular mortality: a cohort study of 8486 primary-care patients

AIMS

Elevated body mass index (BMI) is associated with an increased risk of type 2 diabetes and cardiovascular disease (CVD). This study explored the association between BMI changes in the first 18 months of newly diagnosed type 2 diabetes and the risk of long-term CVD mortality.

METHODS

A total of 8486 patients with newly diagnosed type 2 diabetes and no previous history of CVD or cancer were identified from 84 primary-care centres in Sweden. During the first year after diagnosis, patients were grouped according to BMI change: 'Increase', or ≥+1 BMI unit; 'unchanged', or between +1 and-1 BMI unit; and 'decrease', or ≤-1 BMI unit. Associations between BMI change and CVD mortality, defined as death from stroke, myocardial infarction or sudden death, were estimated using adjusted Cox proportional hazards models (NCT 01121315).

RESULTS

Baseline mean age was 60.0 years and mean BMI was 30.2kg/m(2). Patients were followed for up to 9 years (median: 4.6 years). During the first 18 months, 53.4% had no change in their BMI, while 32.2% decreased and 14.4% increased. Compared with patients with unchanged BMI, those with an increased BMI had higher risks of CVD mortality (hazard ratio: 1.63, 95% CI: 1.11-2.39) and all-cause mortality (1.33, 1.01-1.76). BMI decreases had no association with these risks compared with unchanged BMI: 1.06 (0.76-1.48) and 1.06 (0.85-1.33), respectively.

CONCLUSION

Increased BMI within the first 18 months of type 2 diabetes diagnosis was associated with an increased long-term risk of CVD mortality. However, BMI decrease did not lower the long-term risk of mortality.

Diabetic cardiomyopathy: ongoing controversies in 2012

Diabetic cardiomyopathy is a controversial clinical entity that in its initial state is usually characterized by left ventricular diastolic dysfunction in patients with diabetes mellitus that cannot be explained by coronary artery disease, hypertension, or any other known cardiac disease. It was reported in up to 52-60% of well-controlled type-II diabetic subjects, but more recent studies, using standardized tissue Doppler criteria and more strict patient selection, revealed a much lower prevalence. The pathological substrate is myocardial damage, left ventricular hypertrophy, interstitial fibrosis, structural and functional changes of the small coronary vessels, metabolic disturbance, and autonomic cardiac neuropathy. Hyperglycemia causes myocardial necrosis and fibrosis, as well as the increase of myocardial free radicals and oxidants, which decrease nitric oxide levels, worsen the endothelial function, and induce myocardial inflammation. Insulin resistance with hyperinsulinemia and decreased insulin sensitivity may also contribute to the left ventricular hypertrophy. Clinical manifestations of diabetic cardiomyopathy may include dyspnea, arrhythmias, atypical chest pain, and dizziness. Currently, there is no specific treatment of diabetic cardiomyopathy that targets its pathophysiological substrate, but various therapeutic options are discussed that include improving diabetic control with both diet and drugs (metformin and thiazolidinediones), the use of ACE inhibitors, beta blockers, and calcium channel blockers. Daily physical activity and a reduction in body mass index may improve glucose homeostasis by reducing the glucose/insulin ratio and the increase of both insulin sensitivity and glucose oxidation by the skeletal and cardiac muscles.

The future of thiazolidinedione therapy in the management of type 2 diabetes mellitus

Since their approval, thiazolidinediones (TZDs) have been used extensively as insulin-sensitizers for the management of type 2 diabetes mellitus (T2DM). Activation of peroxisomal proliferator-activated receptor gamma (PPARγ) nuclear receptors by TZDs leads to a vast spectrum of metabolic and antiinflammatory effects. In the past decade, clinicians and scientists across the fields of metabolism, diabetes, liver disease (NAFLD), atherosclerosis, inflammation, infertility, and even cancer have had high hopes about the potential for TZDs to treat many of these diseases. However, an increasing awareness about undesirable "off-target" effects of TZDs have made us rethink their role and be more cautious about the long-term benefits and risks related to their use. This review examines the most relevant work on the benefits and risks associated with TZD treatment, with a focus on the only PPARγ agonist currently available (pioglitazone), aiming to offer the reader a balanced overview about the current and future role of TZDs in the management of insulin-resistant states and T2DM.

Chinese herbal medicine for impaired glucose tolerance: a randomized placebo controlled trial

BACKGROUND

Diabetes remains a major health problem worldwide. Low-risk low-cost alternatives to pharmaceutical interventions are needed where lifestyle modifications have failed. We conducted a double-blind randomised placebo controlled trial to investigate the efficacy of a Chinese herbal formula, Jiangtang Xiaozhi, in treating impaired glucose control and insulin resistance in persons with prediabetes and controlled diabetes.

METHODS

Seventy-one patients with prediabetes or 'controlled' diabetes were randomised to receive 3 capsules of Jiangtang Xiaozhi (n = 39) or placebo (n = 32) three times daily for 16 weeks with a follow up eight weeks later (week 24). The primary outcome was change in glycaemic control as evidenced by fasting blood glucose (FBG), post-prandial plasma glucose and glycosylated haemoglobin (HbA1c). Other measures included change in fasting insulin, insulin resistance and sensitivity, lipids, C-reactive protein (CRP), body mass index (BMI), waist girth, blood pressure (BP), health related quality of life (HRQoL) and safety. Analysis of covariance (ANCOVA) was used to model outcomes at 16 weeks, by treatment group corrected for baseline level of the outcome variable.

RESULTS

In patients receiving Jiangtang Xiaozhi, FBG was not significantly different (p = 0.73) compared to placebo after 16 weeks of treatment (6.3 ± 1.1 mmol/L vs 6.7 ± 1.3 mmol/L). There was a significant difference (p = 0.04) in the mean levels of fasting insulin between the treatment group (11.6 ± 5.5 mmol/L) and the placebo group (22.1 ± 25.9 mmol/L). Insulin resistance slightly decreased in the treatment group (1.58 ± 0.74) compared to that of the placebo group (2.43 ± 1.59) but this change did not reach statistical significance (p = 0.06). Patients taking Jiangtang Xiaozhi had a significant improvement in high-density lipoprotein (HDL) level compared to the placebo group at week 16 (p = 0.03). Mean levels of cholesterol, triglycerides, BMI, waist-girth, HRQoL, BP, CRP and insulin sensitivity were not significantly different between the two groups. The herbal medicine was well tolerated.

CONCLUSIONS

In the current study, the 16 week Jiangtang Xiaozhi treatment did not lower fasting blood glucose, but it improved serum insulin and HDL cholesterol in a Western population with prediabetes or controlled diabetes. Our trial may have been underpowered. Dosage needs to be considered before commencing a longer adequately powered trial.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12612000128897; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=362005.

Metformin and its clinical use: new insights for an old drug in clinical practice

Metformin is generally recommended as first-line treatment in type 2 diabetes, especially in overweight patients, but in recent years new indications for its use have emerged. Metformin has been found to be safe and efficacious both as monotherapy and in combination with all oral antidiabetic agents and insulins. If metformin use during pregnancy and the lactation period is supported by few data, it could be indicated for women with polycystic ovary syndrome, since it could diminish circulating androgens and insulin resistance, thus ameliorating the ovulation rate. Metformin seems to reduce cancer risk, which appears to be increased in diabetics, and is a promising agent for oncoprevention and chemotherapy combinations. Moreover, metformin could find a place in the treatment of non-alcoholic fatty liver disease. Lactic acidosis could be decreased by avoiding metformin use in patients with hypovolemia, sepsis, renal impairment, hypoxic respiratory diseases and heart failure, in the preoperative period and before intravenous injection of contrast media.

PPAR-γ as a therapeutic target in cardiovascular disease: evidence and uncertainty

Peroxisome proliferator-activated receptor γ (PPAR-γ) is a key regulator of fatty acid metabolism, promoting its storage in adipose tissue and reducing circulating concentrations of free fatty acids. Activation of PPAR-γ has favorable effects on measures of adipocyte function, insulin sensitivity, lipoprotein metabolism, and vascular structure and function. Despite these effects, clinical trials of thiazolidinedione PPAR-γ activators have not provided conclusive evidence that they reduce cardiovascular morbidity and mortality. The apparent disparity between effects on laboratory measurements and clinical outcomes may be related to limitations of clinical trials, adverse effects of PPAR-γ activation, or off-target effects of thiazolidinedione agents. This review addresses these issues from a clinician's perspective and highlights several ongoing clinical trials that may help to clarify the therapeutic role of PPAR-γ activators in cardiovascular disease.

Efficacy and safety of exenatide once weekly versus metformin, pioglitazone, and sitagliptin used as monotherapy in drug-naive patients with type 2 diabetes (DURATION-4): a 26-week double-blind study

OBJECTIVE

To test the safety and efficacy of exenatide once weekly (EQW) compared with metformin (MET), pioglitazone (PIO), and sitagliptin (SITA) over 26 weeks, in suboptimally treated (diet and exercise) drug-naive patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Patients were randomized to subcutaneous (SC) EQW 2.0 mg + oral placebo (n = 248), MET 2,000 mg/day + SC placebo (n = 246), PIO 45 mg/day + SC placebo (n = 163), or SITA 100 mg/day + SC placebo (n = 163) for 26 weeks. MET and PIO therapies were increased to maximum-tolerated dosages. Injections with EQW or placebo were administered weekly, while oral medication or placebo was administered daily.

RESULTS

Baseline characteristics were as follows: 59% men, 67% Caucasian, mean age 54 years, HbA(1c) 8.5%, fasting serum glucose 9.9 mmol/L, body weight 87.0 kg, and diabetes duration 2.7 years. HbA(1c) reductions (%) at 26 weeks (least-squares means) with EQW versus MET, PIO, and SITA were -1.53 vs. -1.48 (P = 0.620), -1.63 (P = 0.328), and -1.15 (P < 0.001), respectively. Weight changes (kg) were -2.0 vs. -2.0 (P = 0.892), +1.5 (P < 0.001), and -0.8 (P < 0.001), respectively. Common adverse events were as follows: EQW, nausea (11.3%) and diarrhea (10.9%); MET, diarrhea (12.6%) and headache (12.2%); PIO, nasopharyngitis (8.6%) and headache (8.0%); and SIT, nasopharyngitis (9.8%) and headache (9.2%). Minor (confirmed) hypoglycemia was rarely reported. No major hypoglycemia occurred.

CONCLUSIONS

EQW was noninferior to MET but not PIO and superior to SITA with regard to HbA(1c) reduction at 26 weeks. Of the agents studied, EQW and MET provided similar improvements in glycemic control along with the benefit of weight reduction and no increased risk of hypoglycemia.

Which is the eligible patient to be treated with pioglitazone? The expert view

Pioglitazone has an important role in the treatment of patients with Type 2 diabetes. The drug can help patients to achieve sustained glycemic control and may delay the requirement for insulin. Pioglitazone may provide benefits beyond its effects on glycemia, with data suggesting it may confer anti-atherosclerotic and cardioprotective properties. Attention should be given to possible side effects relating to class effects of TZD, and selection of appropriate patients to be prescribed pioglitazone will enable optimum benefits to be derived from pioglitazone treatment.

Selective modulation of PPARγ activity can lower plasma glucose without typical thiazolidinedione side-effects in patients with Type 2 diabetes

OBJECTIVE

INT131 besylate is a potent non-thiazolidinedione selective peroxisome proliferator-activated receptor γ (PPARγ) modulator (SPPARM) designed to improve insulin sensitivity and glucose metabolism while minimizing the side effects of full agonist thiazolidinediones. This study was conducted to determine short-term efficacy and safety of INT131 besylate in patients with Type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

This was a 4-week randomized, double-blind, placebo-controlled multi-center study with 1 or 10mg INT131 besylate or placebo daily in subjects with T2DM not receiving pharmacotherapy for their hyperglycemia. The primary efficacy analysis was the comparison of treatment groups with respect to least square mean change from baseline to Week 4 of fasting plasma glucose (FPG).

RESULTS

Baseline mean (± S.D.) FPG for the study population was 171 ± 42 mg/dl. Change in FPG (± S.E., mg/dl) from baseline after 4 weeks was 8 ± 8 (P=NS) with placebo, -22 ± 8 with 1mg INT131 besylate (P=.0056) and -46 ± 7 with 10mg INT131 besylate (P<.0001). Modeling of available data from the literature of the effect of rosiglitazone under similar study conditions suggested that 1 mg of INT131 besylate had a similar reduction in FPG as expected with 8 mg of rosiglitazone. INT131 besylate was well tolerated, and the 1 mg dose demonstrated no evidence of fluid retention or weight gain.

CONCLUSIONS

INT131 besylate demonstrated a dose dependent reduction in FPG. The FPG reduction with 1mg INT131 besylate was comparable to the modeled 8 mg dose of rosiglitazone, and did not cause fluid retention or weight gain. These results are consistent with the INT131 SPPARM design.

Thermogenesis and related metabolic targets in anti-diabetic therapy

Exercise, together with a low-energy diet, is the first-line treatment for type 2 diabetes type 2 diabetes . Exercise improves insulin sensitivity insulin sensitivity by increasing the number or function of muscle mitochondria mitochondria and the capacity for aerobic metabolism, all of which are low in many insulin-resistant subjects. Cannabinoid 1-receptor antagonists and β-adrenoceptor agonists improve insulin sensitivity in humans and promote fat oxidation in rodents independently of reduced food intake. Current drugs for the treatment of diabetes are not, however, noted for their ability to increase fat oxidation, although the thiazolidinediones increase the capacity for fat oxidation in skeletal muscle, whilst paradoxically increasing weight gain.There are a number of targets for anti-diabetic drugs that may improve insulin sensitivity insulin sensitivity by increasing the capacity for fat oxidation. Their mechanisms of action are linked, notably through AMP-activated protein kinase, adiponectin, and the sympathetic nervous system. If ligands for these targets have obvious acute thermogenic activity, it is often because they increase sympathetic activity. This promotes fuel mobilisation, as well as fuel oxidation. When thermogenesis thermogenesis is not obvious, researchers often argue that it has occurred by using the inappropriate device of treating animals for days or weeks until there is weight (mainly fat) loss and then expressing energy expenditure energy expenditure relative to body weight. In reality, thermogenesis may have occurred, but it is too small to detect, and this device distracts us from really appreciating why insulin sensitivity has improved. This is that by increasing fatty acid oxidation fatty acid oxidation more than fatty acid supply, drugs lower the concentrations of fatty acid metabolites that cause insulin resistance. Insulin sensitivity improves long before any anti-obesity effect can be detected.

Antioxidant and pancreas-protective effect of red mold fermented products on streptozotocin-induced diabetic rats

BACKGROUND

Red mold fermented products contain various antioxidants, and were mentioned in an ancient Chinese pharmacopoeia of medicinal food and herbs. They were considered useful for the treatment of diabetes. The objective of this study was to determine the antioxidant and pancreas-protective function of red mold fermented products on streptozotocin (STZ)-induced diabetic rats.

RESULTS

Throughout the experimental period (8 weeks), significantly (P < 0.05) lowered plasma glucose, amylase, triglyceride and cholesterol levels were observed in groups treated with red mold fermented products. Diabetic rats showed higher reactive oxygen species (P < 0.05) and lower activities of glutathione disulfide reductase, glutathione reductase and catalase (P < 0.05) in pancreas as compared to normal rats and those treated with red mold fermented products. There were some necrotic cells observed in the pancreas of diabetic rats and pancreatic tissue damaged by STZ in the red mold fermented products supplemented groups was ameliorated.

CONCLUSION

These results indicate that red mold fermented products not only regulate hyperglycemia but also provide prevention against the effects of STZ-induced pancreatic damage.

Regulatory challenges for new drugs to treat obesity and comorbid metabolic disorders

Obesity is a major cause of morbidity and mortality through cardio- and cerebrovascular diseases and cancer. The metabolic consequences of obesity include dyslipidaemia, hypertension, proinflammatory atherogenesis, pre-diabetes and Type 2 diabetes. For a significant proportion of patients, pharmacotherapy to tackle obesity is required as adjunctive support to diet, exercise and lifestyle modification. To this end, the pharmaceutical industry is pursuing many novel drug targets. Although this view is probably not justified, the recent tribulations of rimonabant have created a perception that the regulatory bar for the approval of antiobesity drugs has been raised. Although >5% of placebo-subtracted weight loss maintained over 1 year is the primary efficacy end-point, it is improvements in cardiovascular risk factors that the Food and Drug Administration (FDA) and European Medicines Agency (EMEA) require to grant approval. Safety aspects are also critical in this indication. Many companies are now switching development of their antiobesity drug candidates into other metabolic disorders. Type 2 diabetes is accepted by the industry and FDA, but not EMEA, as the most appropriate alternative. On the other hand, improvements in plasma lipids produced by antiobesity drugs are moderate compared with established therapies, suggesting dyslipidaemia is not a viable development option. Metabolic Syndrome is not accepted by FDA or EMEA as a discrete disease and the agencies will not licence antiobesity drugs for its treatment. The regulatory environment for antiobesity drugs and the spectrum of indications for which they can be approved could change dramatically if positive data for sibutramine emerge from the SCOUT outcome trial.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

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.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

Pioglitazone improves endothelium-dependent vasodilation in hypertensive patients with impaired glucose tolerance in part through a decrease in oxidative stress

BACKGROUND

The aim of this study was to determine pioglitazone treatment restores endothelial function in hypertensive patients with impaired glucose tolerance (IGT).

METHODS AND RESULTS

We evaluated the effects of pioglitazone treatment for 12 weeks on forearm blood flow (FBF) responses to acetylcholine and sodium nitroprusside in 34 hypertensive patients with IGT who were randomly divided into a pioglitazone group (n=17) and an amlodipine monotherapy group (n=17) and in 34 healthy subjects. Pioglitazone, but not amlodipine, increased the FBF response to acetylcholine and decreased urinary excretion of 8-hydroxy-2'-deoxyguanosine. Pioglitazone did not alter sodium nitroprusside-stimulated vasodilation. NG-monomethyl-L-arginine abolished the augmentation of FBF response to acetylcholine after pioglitazone treatment. The increase in maximal FBF response to acetylcholine correlated with the decrease in urinary excretion of 8-hydroxy-2'-deoxyguanosine.

CONCLUSION

Pioglitazone improved endothelial function in hypertensive patients with IGT through an increase in nitric oxide bioavailability by, in part, a decrease in oxidative stress.

Effect of pioglitazone on various parameters of insulin resistance including lipoprotein subclass according to particle size by a gel-permeation high-performance liquid chromatography in newly diagnosed patients with type 2 diabetes

Pioglitazone is an insulin-sensitizing agent that has been reported to have anti-arteriosclerotic effects. The aim of this study was to obtain a better understanding of the mechanism involved in the insulin sensitizing effect of pioglitazone. A total of 50 newly diagnosed patients with type 2 diabetes were enrolled in this study and divided into two groups, 25 of who were treated with 15 mg/day pioglitazone and 25 with 500 mg/day metformin for 12 weeks. Changes in various parameters of insulin resistance including lipoprotein subclass according to particle size determined by high performance liquid chromatography, as well as glucose metabolism, were monitored to determine the relationship between lipoprotein subclass and other insulin resistance parameters. Both pioglitazone and metformin treatment were associated with significant reductions in hyperglycemia, HOMA-IR and HbA1c levels. Pioglitazone treatment, but not metformin treatment resulted in significant reductions in serum large very low-density lipoprotein (VLDL: 44.5-64.0 nm) and increases in serum adiponectin levels (both <0.001). In the pioglitazone group, the change in large VLDL levels correlated positively with changes in HbA1c (r=0.468, P=0.0174), HOMA-IR (r=0.593, P=0.0014), very small LDL (r=0.714, P<0.0001) and net electronegative charged modified-LDL (r=0.412, P=0.0399), and inversely with changes in adiponectin level (r=-0.526, P=0.0061). The results in this study suggest that the hypoglycemic effect of pioglitazone is achieved mainly through improvement of hepatic insulin resistance, and that pioglitazone may have an antiatherosclerotic effect by decreasing serum atherogenic modified-LDL and by increasing adiponectin.

Risk management in the treatment of type 2 diabetes with pioglitazone

INTRODUCTION

Type 2 diabetes mellitus is one of the most important cardiovascular risk factors. Insulin-resistance represents the common mechanism that leads to type 2 diabetes in obese subjects. Pioglitazone is an insulin-sensitizing agent available for treatment of type 2 diabetes. Large clinical trials have demonstrated the effectiveness of pioglitazone in achieving metabolic control and reducing cardiovascular morbidity and mortality.

AIM

The purpose of this article is to review the effectiveness and tolerability of pioglitazone in the prevention and management of atherosclerosis in patients with type 2 diabetes.

EVIDENCE REVIEW

We reviewed the main monotherapy and comparative studies of pioglitazone, and particularly the recent evidence in the field of atherosclerosis and cardiovascular prevention.

PLACE IN THERAPY

The current evidence shows that pioglitazone is an effective option in the treatment of type 2 diabetes. More studies are needed to establish a role for pioglitazone in atherosclerosis prevention beyond glycemic control.

The backbone of oral glucose-lowering therapy: time for a paradigm shift?

The complex array of metabolic abnormalities associated with type 2 diabetes provides a number of new targets for therapeutic intervention. Although the established oral glucose-lowering therapies, metformin and the sulfonylureas, continue to provide the backbone of therapeutic approaches, the thiazolidinediones (TZDs) also play an important role. Further, a new class of oral agents, the dipeptidyl peptidase-IV (DPP-IV) inhibitors, has recently become available with apparent utility in decreasing postprandial glucose excursions. This review examines how the TZDs and the DPP-IV inhibitors might integrate into current treatment strategies, considering not only glycemic goals, but also longer-term benefits such as durability of glycemic control, effect on metabolic parameters and cardiovascular outcomes. A practical approach is taken, reflecting potential clinical situations in which therapeutic intervention is required.

Redefining the role of thiazolidinediones in the management of type 2 diabetes

There is a need to evaluate oral glucose-lowering agents not only for their value in achieving glycemic control but also for their impact on cardiac risk factor modification. This article reviews the evidence base for the two thiazolinediones currently available, pioglitazone and rosiglitazone. These drugs exert their effects through actions affecting metabolic control, lipid profiles, and the vascular wall. They have been shown to be as efficacious in establishing glycemic control, in both monotherapy and combination therapy regimens, as more traditional oral agents, and may be able to sustain that control in the long term. Both thiazolidinediones have demonstrated favorable effects on markers of cardiovascular disease. Evidence from the large PROactive outcomes study suggests that pioglitazone may exert protective effects in patients with type 2 diabetes and macrovascular disease. Thiazolidinediones are generally well tolerated but they can cause weight gain, induce fluid retention, and may contribute to bone loss in postmenopausal women. The place of thiazolidinediones in the management of type 2 diabetes is well established. The potential for additional benefits in reducing macrovascular risk encourages further long-term study of these agents.

Treatment with sitagliptin or metformin does not increase body weight despite predicted reductions in urinary glucose excretion

BACKGROUND

We used a mathematical model to estimate the contribution of urinary glucose excretion (UGE) to reported changes in body weight (BW) following oral antihyperglycemic agent (AHA) therapy. This modeling approach was used to gain novel insight into the mechanisms by which oral AHA affects BW.

METHODS

Twenty-four hour glucose profiles were used to predict UGE before and after treatment with oral AHA. Model-predicted changes in BW due to reduced UGE were compared with reported changes in BW to quantify non-UGE-dependent effects (fluid retention, food intake, and energy expenditure).

RESULTS

In type 2 diabetes patients [hemoglobin A1c (HbA1c) >7.3%], the energy lost to UGE is predicted to decrease an average of 100 kcal/day for each 1% decrease in HbA1c. This effect, alone, is predicted to increase BW 1.4 kg after 6 months. Differences from this value reported for changes in BW with oral AHA therapy (+1.4 kg for pioglitazone and rosiglitazone; -0.4 kg for glyburide; -0.9 kg for sitagliptin and vildagliptin; -2.3 kg for metformin) are therefore predicted to be due to additional, non-UGE-dependent mechanisms.

CONCLUSIONS

Weight gain following thiazolidinedione therapy is predicted to result from both reduced UGE and non-UGE-dependent mechanisms. Reduced UGE alone is predicted to account for most of the weight gain reported following sulfonylurea therapy. Weight loss observed in response to metformin and weight maintenance observed in response to dipeptidyl peptidase-4 inhibitors may result from an increase in satiety, energy expenditure, or both.

Pioglitazone and cardiovascular risk. A comprehensive meta-analysis of randomized clinical trials

AIM

The aim of this meta-analysis of randomized clinical trials (RCT) was to assess whether pioglitazone is also associated with increased cardiovascular risk, as recently reported for rosiglitazone.

METHODS

RCT of pioglitazone were retrieved from Medline (any date up to 31 August 2007; English language only). Unpublished RCT were identified through http://www.clinicaltrials.gov or http://www.fda.gov websites, and results on cardiovascular outcomes were retrieved from investigators and/or sponsors, whenever possible. RCT were included in meta-analysis if pioglitazone was compared with other treatments (placebo, active comparators or no treatment) for at least 4 weeks. Ninety-four trials, 10 of which were unpublished, were retrieved; those included in the analysis, which excluded PROspective PioglitAzone Clinical Trial In MacroVascular Events (PROACTIVE), enrolled 11 268 and 9912 patients in the pioglitazone and comparator groups respectively. Data for analysis, extracted independently by two observers, included all-cause and cardiovascular mortality and incidence of non-fatal coronary events and heart failure. Proportions of outcome measures across treatment groups were compared by odds ratios (ORs) and 95% confidence interval.

RESULTS

Pioglitazone was associated with reduced all-cause mortality [OR 0.30 (0.14-0.63); p < 0.05], with no relevant effect on non-fatal coronary events. The observed increase in incidence of non-fatal heart failure was not statistically significant [OR 1.38 (0.90-2.12)].

CONCLUSION

The use of pioglitazone does not appear to be harmful in terms of cardiovascular events and all-cause deaths.

Metformin therapy and clinical uses

Metformin is now established as a first-line antidiabetic therapy for the management of type 2 diabetes. Its early use in treatment algorithms is supported by lack of weight gain, low risk of hypoglycaemia and its mode of action to counter insulin resistance. The drug's anti-atherosclerotic and cardioprotective effects have recently been confirmed in prospective and retrospective studies, and appear to reflect a collection of glucose-independent effects on the vascular endothelium, suppressant effects on glycation, oxidative stress and formation of adhesion molecules, stimulation of fibrinolysis and favourable effects on the lipid profile. Although avoidance of troublesome gastrointestinal tolerability issues requires careful dose titration, the risk of serious adverse events is considered low provided that contra-indications (especially with respect to renal function) are observed. As many of its actions go beyond glucose lowering, emerging evidence indicates potential benefits in other insulin-resistant states and possibly tumour suppression.

Hepatic dysfunction and insulin insensitivity in type 2 diabetes mellitus: a critical target for insulin-sensitizing agents

The liver plays an essential role in maintaining glucose homeostasis, which includes insulin-mediated processes such as hepatic glucose output (HGO) and uptake, as well as in clearance of insulin itself. In type 2 diabetes, the onset of hyperglycaemia [itself a potent inhibitor of hepatic glucose output (HGO)], alongside hyperinsulinaemia, indicates the presence of hepatic insulin insensitivity. Increased HGO is central to the onset of hyperglycaemia and highlights the need to target hepatic insulin insensitivity as a central component of glucose-lowering therapy. The mechanisms underlying the development of hepatic insulin insensitivity are not well understood, but may be influenced by factors such as fatty acid oversupply and altered adipocytokine release from dysfunctional adipose tissue and increased liver fat content. Furthermore, although the impact of insulin insensitivity as a marker of cardiovascular disease is well known, the specific role of hepatic insulin insensitivity is less clear. The pharmacological tools available to improve insulin sensitivity include the biguanides (metformin) and thiazolidinediones (rosiglitazone and pioglitazone). Data from a number of sources indicate that thiazolidinediones, in particular, can improve multiple aspects of hepatic dysfunction, including reducing HGO, insulin insensitivity and liver fat content, as well as improving other markers of liver function and the levels of mediators with potential involvement in hepatic function, including fatty acids and adipocytokines. The current review addresses this topic from the perspective of the role of the liver in maintaining glucose homeostasis, its key involvement in the pathogenesis of type 2 diabetes and the tools currently available to reduce hepatic insulin insensitivity.

Performing meta-analysis with incomplete statistical information in clinical trials

BACKGROUND

Results from clinical trials are usually summarized in the form of sampling distributions. When full information (mean, SEM) about these distributions is given, performing meta-analysis is straightforward. However, when some of the sampling distributions only have mean values, a challenging issue is to decide how to use such distributions in meta-analysis. Currently, the most common approaches are either ignoring such trials or for each trial with a missing SEM, finding a similar trial and taking its SEM value as the missing SEM. Both approaches have drawbacks. As an alternative, this paper develops and tests two new methods, the first being the prognostic method and the second being the interval method, to estimate any missing SEMs from a set of sampling distributions with full information. A merging method is also proposed to handle clinical trials with partial information to simulate meta-analysis.

METHODS

Both of our methods use the assumption that the samples for which the sampling distributions will be merged are randomly selected from the same population. In the prognostic method, we predict the missing SEMs from the given SEMs. In the interval method, we define intervals that we believe will contain the missing SEMs and then we use these intervals in the merging process.

RESULTS

Two sets of clinical trials are used to verify our methods. One family of trials is on comparing different drugs for reduction of low density lipprotein cholesterol (LDL) for Type-2 diabetes, and the other is about the effectiveness of drugs for lowering intraocular pressure (IOP). Both methods are shown to be useful for approximating the conventional meta-analysis including trials with incomplete information. For example, the meta-analysis result of Latanoprost versus Timolol on IOP reduction for six months provided in 1 was 5.05 +/- 1.15 (Mean +/- SEM) with full information. If the last trial in this study is assumed to be with partial information, the traditional analysis method for dealing with incomplete information that ignores this trial would give 6.49 +/- 1.36 while our prognostic method gives 5.02 +/- 1.15, and our interval method provides two intervals as Mean in [4.25, 5.63] and SEM in [1.01, 1.24].

CONCLUSION

Both the prognostic and the interval methods are useful alternatives for dealing with missing data in meta-analysis. We recommend clinicians to use the prognostic method to predict the missing SEMs in order to perform meta-analysis and the interval method for obtaining a more cautious result.

Comparison of the effects of pioglitazone and metformin on hepatic and extra-hepatic insulin action in people with type 2 diabetes

OBJECTIVE

To determine mechanisms by which pioglitazone and metformin effect hepatic and extra-hepatic insulin action.

RESEARCH DESIGN AND METHODS

Thirty-one subjects with type 2 diabetes were randomly assigned to pioglitazone (45 mg) or metformin (2,000 mg) for 4 months.

RESULTS

Glucose was clamped before and after therapy at approximately 5 mmol/l, insulin raised to approximately 180 pmol/l, C-peptide suppressed with somatostatin, glucagon replaced at approximately 75 pg/ml, and glycerol maintained at approximately 200 mmol/l to ensure comparable and equal portal concentrations on all occasions. Insulin-induced stimulation of glucose disappearance did not differ before and after treatment with either pioglitazone (23 +/- 3 vs. 24 +/- 2 micromol x kg(-1) x min(-1)) or metformin (22 +/- 2 vs. 24 +/- 3 micromol x kg(-1) x min(-1)). In contrast, pioglitazone enhanced (P < 0.01) insulin-induced suppression of both glucose production (6.0 +/- 1.0 vs. 0.2 +/- 1.6 micromol x kg(-1) x min(-1)) and gluconeogenesis (n = 11; 4.5 +/- 0.9 vs. 0.8 +/- 1.2 micromol x kg(-1) x min(-1)). Metformin did not alter either suppression of glucose production (5.8 +/- 1.0 vs. 5.0 +/- 0.8 micromol x kg(-1) x min(-1)) or gluconeogenesis (n = 9; 3.7 +/- 0.8 vs. 2.6 +/- 0.7 micromol x kg(-1) x min(-1)). Insulin-induced suppression of free fatty acids was greater (P < 0.05) after treatment with pioglitazone (0.14 +/- 0.03 vs. 0.06 +/- 0.01 mmol/l) but unchanged with metformin (0.12 +/- 0.03 vs. 0.15 +/- 0.07 mmol/l).

CONCLUSIONS

Thus, relative to metformin, pioglitazone improves hepatic insulin action in people with type 2 diabetes, partly by enhancing insulin-induced suppression of gluconeogenesis. On the other hand, both drugs have comparable effects on insulin-induced stimulation of glucose uptake.

Thiazolidinediones-improving endothelial function and potential long-term benefits on cardiovascular disease in subjects with type 2 diabetes

Endothelial dysfunction, which leads to impaired vasodilation, is an early event in the development of atherosclerosis. A number of mechanisms involving, for example, cell adhesion molecules, chemokines, and cytokines, contribute to this inflammatory disease, and insulin resistance plays a cardinal role in accelerating these processes. Hyperglycemia and other metabolic abnormalities that are commonly associated with insulin resistance also contribute to impaired endothelial function. In addition, the important role of the endothelium in damage repair following a cardiovascular event is emerging. The combination of proatherogenic factors in patients with type 2 diabetes results in blunted endothelial function and an increased risk of cardiovascular disease. Insulin-sensitizing agents such as thiazolidinediones have demonstrated a number of clinical benefits, including anti-inflammatory and antithrombotic properties, which may impact on the course of atherosclerosis. Recent studies have demonstrated that thiazolidinediones improve endothelial function in subjects with and without type 2 diabetes.