Downregulation of the proinflammatory state of circulating mononuclear cells by short-term treatment with pioglitazone in patients with type 2 diabetes mellitus and coronary artery disease.

Background. This study was performed to investigate the influence of a short-term treatment with pioglitazone versus placebo on inflammatory activation of mononuclear cells (mRNA expression/protein secretion of inflammatory markers). Methods and Results. Sixty-three patients with well-controlled type 2 diabetes (52 males, 11 females, age (Mean ± SD): 66 ± 7 yrs, disease duration: 6.6 ± 9.6 yrs, HbA1c: 6.7 ± 0.6%) were randomized to additional 45 mg of pioglitazone or placebo to their existing metformin and sulfonylurea therpay for four weeks in a double-blind study design. Protein risk marker levels (hsCRP, MMP-9, MCP-1, etc.) and the expression of NFκB subunits and NFκB-modulated cytokines from isolated peripheral monocyte/macrophages were determined at baseline and endpoint. There were no changes in HbA1c, but significant biomarker improvements were seen with pioglitazone only. The mRNA marker expression was downregulated by pioglitazone and further up-regulated with placebo (e.g., P105 pioglitazone: -19%/placebo: +6%, RelA: -20%/+2%, MMP-9: -36%/+9%, TNFα: -10%/+14%, P < 0.05 between groups in all cases). Conclusions. Pioglitazone very rapidly down-regulated the activated state of peripheral monocytes/macrophages as assessed by mRNA expression of NFκB and NFκB-modulated cytokines and decreased plasma levels of cardiovascular risk marker proteins independent of glycemic control.

Increased prevalence of cardiovascular disease and risk biomarkers in patients with unknown type 2 diabetes visiting cardiology specialists: results from the DIASPORA study.

BACKGROUND: Patients with diabetes mellitus and IGT have a high risk for cardiovascular events. It is tempting to speculate that these patients are often first seen by cardiologists. DESIGN: This cross-sectional study investigates the diabetes prevalence in cardiology care units and the correlated metabolic conditions as assessed by several circulating biomarkers. METHODS: Patients aged 55 or older with suspected or overt coronary heart disease were eligible for trial participation. Fasting blood samples were drawn from patients to determine HOMA score, glycaemic and lipid profile, and several risk biomarkers. An OGTT was performed in patients without known diabetes. RESULTS: We enrolled 530 patients (181 male, 349 female, mean age, 68+/-7 years) in this study from 22 German cardiology centres; 156 patients (29.4%) had known diabetes and OGTT revealed that 184 patients (34.7%) had no diabetes, 106 patients (20.0%) had IGT or IFG and 84 patients (15.9%) were newly diagnosed with diabetes. Increased cardiovascular risk as reflected by increased hsCRP, ICAM and MMP-9 values was observed in diabetes patients. A higher cardiovascular biomarkers risk profile was seen in the IGT/IFG cohort. CONCLUSIONS: This study confirms the observation that one third of patients of a cardiologic care unit suffer from impaired glucose regulation. Furthermore, the cardiology patients with previously unknown glucose homeostasis abnormalities had a higher prevalence of macrovacular disease and an impaired biomarker risk profile. This study underlines the importance of joint treatment efforts by cardiologists in concert with diabetologists for treatment of this patient group at high risk for cardiovascular events.

The IRIS V study: pioglitazone improves systemic chronic inflammation in patients with type 2 diabetes under daily routine conditions.

BACKGROUND: The peroxisome proliferator-activated receptor-gamma agonist pioglitazone is established as a drug to treat patients with type 2 diabetes mellitus. In addition to lowering blood glucose levels, one of the favorable effects of pioglitazone is improvement of systemic chronic inflammation particularly affecting vessel walls. The effect can be monitored by the measurement of the biomarker C-reactive protein in the range of 0-10 mg/L (high-sensitivity C-reactive protein [hsCRP]). This observational trial was performed to evaluate the effects of pioglitazone on hsCRP values in a large population under daily life conditions. METHODS: A total of 1,170 subjects could be included into the final analysis (633 men, 537 women; age [mean +/- SD], 63.5 +/- 10.4 years, body mass index, 31.0 +/- 5.5 kg/m2; duration of diabetes, 6.9 +/- 8.1 years; glycosylated hemoglobin [HbA1c], 7.5 +/- 1.1%). All patients were glitazone-naive prior to study entry. The patients received pioglitazone alone or in combination with their previous treatment (acarbose, sulfonylurea drugs, and/or metformin). Patients were evaluated at baseline and after 10 +/- 2 weeks and 20 +/- 2 weeks of treatment. Observation parameters were fasting blood glucose, lipids, and blood pressure. The level of hsCRP was determined in a central laboratory at baseline and at end point. RESULTS: All markers showed a significant improvement at trial end point. A decrease of hsCRP (baseline 3.3 +/- 1.0 mg/L vs. end point 2.8 +/- 2.3 mg/L, P < 0.01), HbA1c (7.5 +/- 1.1% vs. 6.8 +/- 0.9%, P < 0.001), fasting blood glucose (8.7 +/- 2.6 mM vs. 7.2 +/- 2.1 mM, P < 0.001), low-density lipoproteins (3.3 +/- 1.0 mM vs. 3.2 +/- 0.9 mM, P < 0.001), and triglycerides (2.4 +/- 2.0 mM vs. 2.2 +/- 2.5 mM, P < 0.001) and an increase in high-density lipoproteins (1.3 +/- 0.4 mM vs. 1.4 +/- 0.4 mM, P < 0.001) was observed. Parallel to the metabolic improvement, both systolic and diastolic blood pressure values were reduced (141 +/- 17 mm Hg vs. 137 +/- 15 mm Hg and 83 +/- 9 mm Hg vs. 80 +/- 9 mm Hg, respectively; P < 0.001 in both cases). CONCLUSIONS: These observational results, obtained from a nonselected patient population under daily routine conditions, confirm the benefits of pioglitazone treatment on blood glucose, lipid metabolism, and blood pressure. The results show that pioglitazone treatment improves chronic vascular inflammation, which may be associated with reduced cardiovascular risk.

Effects of pioglitazone and/or simvastatin on low density lipoprotein subfractions in non-diabetic patients with high cardiovascular risk: A sub-analysis from the PIOSTAT study.

BACKGROUND: We analyzed the efficacy and possible synergistic actions of pioglitazone and simvastatin monotherapy versus their combination on LDL subfractions from a subpopulation from the PIOSTAT three-arm randomized controlled trial. PPARgamma agonists, such as pioglitazone, improve insulin sensitivity and glycemic control and appear to lower the concentration of atherogenic small dense LDL particles. Insulin resistance frequently occurs in non-diabetic patients with cardiovascular disease. Statins, such as simvastatin, reduce cardiovascular events by lowering LDL-C. So far, only scarce information exists for comparative efficacy and possible synergistic effects of combination therapy on LDL subfractions, cholesterol particle load, and particle number of atherogenic small dense LDL. METHODS: 125 non-diabetic patients with high cardiovascular risk were randomized to therapy with pioglitazone 45 mg/day, simvastatin 40 mg/day, or the combination of both, for 12 weeks. In the present sub-study, LDL subfractions from 88 patients were separated by very-fast ultracentrifugation. RESULTS: Simvastatin monotherapy significantly reduced cholesterol and triglyceride concentrations in IDL, LDL1, and LDL2. The lipid concentrations and lipid loads in LDL3 remained unchanged. By contrast, treatment with pioglitazone reduced the cholesterol concentration in LDL3 (density 1.040-1.066 kg/l) from 0.38 to 0.31 mmol/l (p=0.0004) and of the cholesterol load per particle from 1058 to 934 mol/mol (p=0.0149). Even greater reductions of cholesterol in LDL3 were observed with the combination of pioglitazone and simvastatin: from 0.38 to 0.29 mmol/l (p=0.0006) and from 1021 to 903 mol/mol (p=0.0011), respectively. In addition, combination therapy reduced the particle number of LDL3 from 356 to 316 nmol/l (p=0.0074). CONCLUSIONS: Simvastatin preferentially lowered LDL1 and LDL2 subfractions, whereas pioglitazone reduced LDL3 cholesterol and cholesterol load. In addition, the combination reduced the LDL3 particle number. Thus, our data suggest a synergistic action of pioglitazone and simvastatin on atherogenicity of small dense LDL particles.

Pioglitazone improves metabolic markers in patients with type 2 diabetes independently from physical activities: results from the IRIS III study.

AIM: Pioglitazone is an established peroxisome proliferator-activated receptor gamma agonist for the treatment of insulin resistance in patients with type 2 diabetes mellitus. This analysis of the observational IRIS III study was performed to evaluate the effects of pioglitazone treatment in relation to the degree of physical exercise activities in a large patient population under daily life conditions. METHODS: A total of 1298 patients out of 2092 enrolled into the IRIS III study who had provided information about their exercise level could be included in the final analysis (622 female, 676 male; age: 63.1 +/- 10.4 years, diabetes duration: 6.6 +/- 5.0 years, mean +/- SD). All patients were glitazone naïve prior to study entry. They received pioglitazone in addition to their previous oral antidiabetic treatment. The patients were stratified according to their physical activity level (never, sometimes, and regularly). Data were evaluated at baseline and after 20 +/- 2 weeks of treatment. Observation parameters were fasting blood glucose, lipids, and blood pressure. Hemoglobin A1c (HbA1c) was determined in a central laboratory, and insulin sensitivity was assessed by the IRIS II score. RESULTS: Glycemic control, blood pressure, and the lipid profile improved independently from the degree of physical activity (e.g., no exercise vs frequent exercise: DeltaHbA1c: -0.89 +/- 1.2% vs -0.72 +/- 1.1%, not significant). A positive impact of exercise on insulin resistance could be observed at baseline, which, however, was further decreased by pioglitazone treatment [IRIS II score (baseline/end point): no exercise vs frequent exercise: 74.0 +/- 15.9/62.5 +/- 20.2 vs 66.7 +/- 19.0/58.0 +/- 21.8, p < 0.001/not significant]. CONCLUSIONS: These observational results, obtained from a nonselected patient population under daily routine conditions, confirm that the benefits of pioglitazone treatment on glycemic control, lipid metabolism, and blood pressure are independent from physical activity. Exercise has a positive influence on insulin sensitivity, but pioglitazone shows additional favorable effects and is, therefore, recommended for use independently from the activity level of the patients.

Relaxin expression correlates significantly with serum fibrinogen variation in response to antidiabetic treatment in women with type 2 diabetes mellitus.

AIM: Diabetes is associated with aberrant coagulation. Relaxin, an insulin-like peptide hormone, is a candidate to be involved in the underlying molecular mechanisms. Therefore, the present study investigated the correlation of relaxin expression with fibrinogen levels in diabetes patients undergoing oral antidiabetic treatment. METHOD: In total, 192 type 2 diabetes patients were enrolled into the study. The patients were randomized to receive either pioglitazone or glimepiride for 26 weeks. Blood was drawn at baseline and at the end of the study to measure the concentrations of relaxin and fibrinogen with an enzyme-linked immunosorbent assay and a turbimetric method, respectively. In addition, platelets were counted at both time points. RESULTS: Total datasets were available from 161 patients (age 62.5 +/- 8.1 years, mean +/- standard deviation; 58 women, 103 men). The median initial parameter concentrations were: relaxin, 27.4 pg/ml (range 0.4 - 380 pg/ml); fibrinogen, 3.0 g/l (range 1.1 - 7.9 g/l); platelets, 217,000/microl (range 51,000 - 547 000/microl). The data were analyzed according to the increase or decrease of each parameter after therapy compared with baseline. There was a significant correlation of relaxin variation with fibrinogen variation, seen particularly in the female subgroup (p < 0.05). The correlation was independent of the antidiabetic medication. CONCLUSION: The data suggest that there is a correlation between fibrinogen levels and relaxin expression. Relaxin may exert its cardioprotective properties after pathologic fibrinogen increase. This regulation may be affected by diabetes. As a consequence, cardiovascular risk may increase in women with aberrant relaxin functionality.

Relaxin expression correlates significantly with serum changes in VEGF in response to antidiabetic treatment in male patients with type 2 diabetes mellitus.

Recent studies indicate that relaxin as well as VEGF possess cardioprotective properties. This study aimed to determine the association of relaxin with VEGF in patients with type 2 diabetes. We therefore analyzed samples from a recent study showing the benefits of anti-diabetic treatment on cardiovascular risk markers independently from glycemic control. VEGF, relaxin and markers of endothelial dysfunction, s-ICAM-1 and s-VCAM-1, were compared after 26 +/- 2 weeks of antidiabetic treatment with pioglitazone or glimepiride with their base line values. A total of 151 data sets (patients age, 62.7 +/- 8.1 years, diabetes duration, 6.8 +/- 6.6 years, 57 women, 94 men) were available for the analysis. Baseline values were in median, relaxin: 27.4 pg/mL 125% quartile 15.8; 75% quartile: 45.21, s-ICAM-1: 294 ng/mL [25% quartile: 260; 75% quartile: 331], s-VCAM-1: 677 ng/mL [25% quartile: 589; 75% quartile 871], VEGF: 350 pg/mL [25% quartile: 251; 75% quartile: 514]. Parameter variation after therapy showed a significant correlation of relaxin expression with VEGF expression (p = 0.02) in the entire study group. The correlation was seen in the subgroup of male patients (p < 0.01) but did not reach significance in the female patients (p = 0.71). No further correlation was observed analyzing the other investigated parameters. Our data suggest that relaxin may exert its cardioprotective action possibly via VEGF increase, particularly in men. In women, other pathways may superimpose this effect. In conclusion, our study supports the hypothesis of different regulating pathways and effects of relaxin in men and women also in patients with type 2 diabetes.

Effect of simvastatin and/or pioglitazone on insulin resistance, insulin secretion, adiponectin, and proinsulin levels in nondiabetic patients at cardiovascular risk--the PIOSTAT Study.

We investigated the effect of pioglitazone in comparison with and in combination with simvastatin on insulin resistance, plasma adiponectin, postprandial plasma glucose, insulin, and intact proinsulin levels in a nondiabetic population at cardiovascular risk. One hundred twenty-five nondiabetic patients at cardiovascular risk were randomized to pioglitazone (PIO), pioglitazone and simvastatin (PIO/SIM), or simvastatin (SIM) treatments. Blood samples were taken for the measurement of adiponectin and lipid levels. In addition, an oral glucose load with the measurements of glucose, insulin, and intact proinsulin levels was performed. Adiponectin levels increased from 14.0+/-8.2 to 27.6+/-14.5 microg/mL (P<.0001) during PIO treatment and from 11.7+/-10.0 to 26.7+/-15.7 microg/mL (P<.0001) during PIO/SIM treatment. A decrease in adiponectin levels from 15.5+/-12.7 to 11.6+/-7.0 microg/mL (P<.05) was observed during SIM treatment. Although fasting intact proinsulin levels remained unchanged, the increase in postprandial intact proinsulin levels could be reduced from 29.5+/-21.4 to 22.1+/-17.5 pmol/L (P<.01) during PIO treatment and from 24.3+/-27.4 to 21.1+/-16.5 mmol/L (P<.05) during PIO/SIM treatment. Lipid parameters improved during SIM treatment but not during PIO treatment. Combined treatment with PIO/SIM was superior in improving overall cardiovascular risk profile than every single drug.

Anti-inflammatory effects of pioglitazone and/or simvastatin in high cardiovascular risk patients with elevated high sensitivity C-reactive protein: the PIOSTAT Study.

OBJECTIVES: The purpose of this study was to test the safety and efficacy of pioglitazone and simvastatin in combination versus each drug individually in non-diabetic subjects with cardiovascular disease (CVD) and elevated high-sensitivity C-reactive protein (hs-CRP) levels. BACKGROUND: Low-grade inflammation is a pathogenic factor for atherosclerosis. High-sensitivity CRP, matrix metalloproteinase (MMP)-9, and plasminogen activator inhibitor (PAI)-1 are markers of inflammation. Statins and peroxisome proliferator-activated receptor (PPAR)-gamma agonists lower inflammatory markers and reduce CVD in type 2 diabetes. METHODS: In a 12-week, prospective, double-blind trial, 125 subjects were randomized to simvastatin or pioglitazone plus placebo or a simvastatin/pioglitazone combination. We tested changes in hs-CRP by analysis of covariance. A subgroup analysis was performed in patients with and without the metabolic syndrome (MetS). The correlation between changes in hs-CRP and homeostasis model assessment (HOMA; a measure of insulin resistance) was calculated with the Spearman's rank test. RESULTS: At baseline, there were no significant between-group differences. At 12 weeks, pioglitazone and simvastatin monotherapies significantly reduced hs-CRP (3.64 +/- 2.42 mg/l to 2.48 +/- 1.77 mg/l and 3.26 +/- 2.02 mg/l to 2.81 +/- 2.11 mg/l) and the combination regimen had an additive effect (from 3.49 +/- 1.97 mg/l to 2.06 +/- 1.42 mg/l, p < 0.001). For subgroups, the difference between monotherapy and combination therapy was only significant for simvastatin versus simvastatin plus pioglitazone in patients without MetS. Homeostasis model assessment decreased in those receiving pioglitazone, and the correlation between changes in HOMA and hs-CRP was significant (r = 0.43; p < 0.05). The PAI-1 decreased significantly in the pioglitazone groups only, and MMP-9 was also significantly lowered in the pioglitazone groups. No treatment-related serious adverse events occurred in any group. CONCLUSIONS: Pioglitazone, probably by reducing insulin resistance, has additive anti-inflammatory effects to simvastatin in non-diabetic subjects with CVD and high hs-CRP.

Association of high-sensitive C-reactive protein with advanced stage beta-cell dysfunction and insulin resistance in patients with type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus is associated with increased cardiovascular risk. One laboratory marker for cardiovascular risk assessment is high-sensitivity C-reactive protein (hsCRP). METHODS: This cross-sectional study attempted to analyze the association of hsCRP levels with insulin resistance, beta-cell dysfunction and macrovascular disease in 4270 non-insulin-treated patients with type 2 diabetes [2146 male, 2124 female; mean age +/-SD, 63.9+/-11.1 years; body mass index (BMI) 30.1+/-5.5 kg/m(2); disease duration 5.4+/-5.6 years; hemoglobin A(1c) (HbA(1c)) 6.8+/-1.3%]. It consisted of a single morning visit with collection of a fasting blood sample. Observational parameters included several clinical scores and laboratory biomarkers. RESULTS: Stratification into cardiovascular risk groups according to hsCRP levels revealed that 934 patients had low risk (hsCRP <1 mg/L), 1369 patients had intermediate risk (hsCRP 1-3 mg/L), 1352 patients had high risk (hsCRP >3-10 mg/L), and 610 patients had unspecific hsCRP elevation (>10 mg/L). Increased hsCRP levels were associated with other indicators of diabetes-related cardiovascular risk (homeostatic model assessment, intact proinsulin, insulin, BMI, beta-cell dysfunction, all p<0.001), but showed no correlation with disease duration or glucose control. The majority of the patients were treated with diet (34.1%; hsCRP levels 2.85+/-2.39 mg/L) or metformin monotherapy (21.1%; 2.95+/-2.50 mg/L hsCRP). The highest hsCRP levels were observed in patients treated with sulfonylurea (17.0%; 3.00+/-2.43 mg/L). CONCLUSIONS: Our results indicate that hsCRP may be used as a cardiovascular risk marker in patients with type 2 diabetes mellitus and should be evaluated in further prospective studies.

Influence of glucose control and improvement of insulin resistance on microvascular blood flow and endothelial function in patients with diabetes mellitus type 2.

OBJECTIVE: The study was performed to investigate the effect of improving metabolic control with pioglitazone in comparison to glimepiride on microvascular function in patients with diabetes mellitus type 2. METHODS: A total of 179 patients were recruited and randomly assigned to one treatment group. Metabolic control (HbA1c), insulin resistance (HOMA index), and microvascular function (laser Doppler fluxmetry) were observed at baseline and after 3 and 6 months. RESULTS: HbA1c improved in both treatment arms (pioglitazone: 7.52 +/- 0.85% to 6.71 +/- 0.89%, p < .0001; glimepiride: 7.44 +/- 0.89% to 6.83 +/- 0.85%, p < .0001). Insulin-resistance decreased significantly in the pioglitazone group (6.15 +/- 4.05 to 3.85 +/- 1.92, p < .0001) and remained unchanged in the glimepiride group. The microvascular response to heat significantly improved in both treatment groups (pioglitazone 48.5 [15.2; 91.8] to 88.8 [57.6; 124.1] arbitrary units [AU], p < .0001; glimepiride 53.7 [14.1; 91.9] to 87.9 [52.9, 131.0] AU, p < .0001, median [lower and upper quartile]). Endothelial function as measured with the acetylcholine response improved in the pioglitazone group (38.5 [22.2; 68.0] to 60.2 [36.9; 82.8], p = .0427) and remained unchanged in the glimepiride group. CONCLUSIONS: Improving metabolic control has beneficial effects in microvascular function in type 2 diabetic patients. Treatment of type 2 diabetic patients with pioglitazone exerts additional effects on endothelial function beyond metabolic control.

Improvement of cardiovascular risk markers by pioglitazone is independent from glycemic control: results from the pioneer study.

OBJECTIVES: This study was performed to assess whether the anti-inflammatory and antiatherogenic effects of pioglitazone suggested by animal experiments are reproducible in man and independent from improvements in metabolic control. BACKGROUND: Type 2 diabetes is associated with increased cardiovascular risk. METHODS: A total of 192 patients were enrolled into a six-month, prospective, open-label, controlled clinical study. They were randomized to receive either pioglitazone (45 mg) or glimepiride (1 to 6 mg, with the intent to optimize therapy). Biochemical and clinical markers to assess therapeutic effects included HbA1c, fasting glucose, insulin, adiponectin, lipids, high-sensitivity C-reactive protein (hsCRP), intracellular adhesion molecule, vascular cell adhesion molecule, vascular endothelial growth factor, fibrinogen, von Willebrand factor, matrix metalloproteinase (MMP)-9, monocyte chemoattractant protein (MCP)-1, soluble CD40 ligand, and carotid intima-media thickness (IMT). RESULTS: The study was completed by 173 patients (66 female, 107 male; age [+/- SD]: 63 +/- 8 years; disease duration: 7.2 +/- 7.2 years; HbA1c: 7.5 +/- 0.9%; pioglitazone arm: 89 patients). A comparable reduction in HbA1c was seen in both groups (p < 0.001). In the pioglitazone group, reductions were observed for glucose (p < 0.001 vs. glimepiride group at end point), insulin (p < 0.001), low-density lipoprotein/high-density lipoprotein ratio (p < 0.001), hsCRP (p < 0.05), MMP-9 (p < 0.05), MCP-1 (p < 0.05), and carotid IMT (p < 0.001), and an increase was seen in high-density lipoprotein (p < 0.001) and adiponectin (p < 0.001). Spearman ranks analysis revealed only one correlation between the reduction in cardiovascular risk parameters and the improvement in the metabolic parameters (MMP-9 and fasting blood glucose, p < 0.05) CONCLUSIONS: This prospective study gives evidence of an anti-inflammatory and antiatherogenic effect of pioglitazone versus glimepiride. This effect is independent from blood glucose control and may be attributed to peroxisome proliferator-activated receptor gamma activation.

IRIS II study: intact proinsulin is confirmed as a highly specific indicator for insulin resistance in a large cross-sectional study design.

BACKGROUND: The cross-sectional IRIS-II study tried to assess the prevalence of insulin resistance and macrovascular disease in orally treated patients with Type 2 diabetes. METHODS: In total, 4,270 patients were enrolled into the study (2,146 male, 2,124 female; mean +/- SD age 63.9 +/- 11.1 years; body mass index 30.1 +/- 5.5 kg/m2; duration of disease 5.4 +/- 5.6 years; hemoglobin A1c 6.8 +/- 1.3%). The study consisted of a single morning visit with completion of a standardized questionnaire and collection of a fasting blood sample. RESULTS: The mean intact proinsulin value was 11.4 +/- 12.4 pmol/L (normal range < 10 pmol/L). Homeostasis model assessment resulted in 1,147 insulin-sensitive patients (26.9%) and 3,123 patients (73.1%) with insulin resistance. Of the latter patients 1,465 (34.3% of all patients) had also elevated intact proinsulin values, while 1,658 (38.8%) had no proinsulin elevation. In contrast, 1,042 (24.4%) of the insulin-sensitive patients had normal intact proinsulin, and only 105 (2.4%) had elevated intact proinsulin concentrations (chi2 test P < 0.0001). A specificity of 93.2% (sensitivity 46.9%) was calculated for elevated intact proinsulin as an indirect marker for insulin resistance. Of the 1,451 patients treated with sulfonylurea 52% had elevated intact proinsulin values and increased prevalence of cardiovascular complications (odds ratio 1.45). CONCLUSION: Type 2 patients with elevated fasting intact proinsulin values can be regarded as being insulin resistant. The results confirm that fasting intact proinsulin is a suitable measure for beta-cell dysfunction and insulin resistance in type 2 diabetes and may be used to support therapeutic decisions.

Potential role of oral thiazolidinedione therapy in preserving beta-cell function in type 2 diabetes mellitus.

Worsening glycaemic control in type 2 diabetes mellitus relates to a decline in beta-cell function, associated with impaired negative feedback regulation of insulin release. Insulin resistance, the 'traditional' cornerstone defect of type 2 diabetes, leads to an array of adverse effects on beta cells, including hypertrophy, apoptosis and those caused by lipotoxicity and glucotoxicity. In particular, increased levels of free fatty acids and their metabolites are thought to diminish both insulin synthesis and glucose-stimulated insulin secretion. Thiazolidinediones are synthetic peroxisome proliferator-activated receptor-gamma agonists that decrease insulin resistance but, as in vitro and in vivo studies suggest, may have direct beneficial effects on pancreatic beta cells. Troglitazone, for example, demonstrated improvements in insulin secretory capacity in isolated pancreatic islets from Wistar rats and a hamster beta-cell line. In vivo studies reveal thiazolidinediones promote beta-cell survival and regranulation as well as maintenance of beta-cell mass and reduction in amyloid deposition. Clinical evidence for thiazolidinediones is largely derived from comparative trials, mainly against sulfonylureas and metformin. Data at 2 years from a number of trials are now available and establish the positive effects of thiazolidinediones on glycaemic control. Empirical evidence showing decreases in fasting plasma insulin levels with pioglitazone and rosiglitazone indicate thiazolidinediones also improve insulin sensitivity. A possible effect of thiazolidinediones on normalising asynchronous insulin secretion, as assessed in a short-term placebo-controlled study, is less established. However, recent and ongoing clinical studies are focusing attention on verifying animal and other data, which support the notion that thiazolidinediones have beneficial effects on beta-cell function. These clinical studies have shown thiazolidinediones capable of preventing or delaying the development of type 2 diabetes in a high-risk population; restoring the first-phase insulin response; and improving secretory responses to oscillations in plasma glucose levels. Many of these effects appear to be independent of improvements in insulin sensitivity. Other research efforts are examining the potential cardiovascular protective effects of thiazolidinediones. Available data imply thiazolidinediones are associated with cardiovascular risk reduction, although results from large, clinical outcome trials, currently in progress, are still needed. Improved understanding of the role that declining beta-cell function has in the development of type 2 diabetes has drawn attention to the need for hypoglycaemic agents that can address this process. Emerging evidence suggests thiazolidinediones offer specific benefits for preventing or delaying the decline in beta-cell function and, thereby, a substrate for early intervention efforts aimed at lowering the worldwide burden of type 2 diabetes.

A comparison of the effects of thiazolidinediones and metformin on metabolic control in patients with type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus is a condition characterized by impaired insulin secretion and resistance to insulin-mediated glucose uptake and utilization. A number of oral antidiabetic medication are available for its treatment, including metformin and the thiazolidinediones (TZDs). The TZDs have been shown to improve insulin resistance, and it has been suggested that metformin has similar effects. Although both types of agents improve glycemic control, their mechanisms of action and effects on metabolic processes differ. OBJECTIVE: The goal of this review was to compare the effects of TZDs and metformin on metabolic control in patients with type 2 diabetes. METHODS: A search of MEDLINE to March 2004 using the terms metformin and biguanides, and thiazolidinediones and glitazones was conducted to identify preclinical and clinical studies focusing on the mechanisms of action and comparative effects of TZDs and metformin. Also searched were published abstracts from recent major diabetes and endocrinology conferences. RESULTS: In the studies reviewed, both TZDs and metformin demonstrated the ability to improve glycemic control, although long-term monotherapy with TZDs appeared to be more effective than metformin. There continues to be debate about whether metformin is more effective than TZDs in terms of inhibition of hepatic glucose production. However, various studies have found TZDs to be more effective in promoting an increase in whole-body insulin sensitivity. With respect to lipid metabolism, patients who received TZDs had a greater reduction in concentrations of both plasma triglycerides and free fatty acids. Metformin was more effective in promoting weight loss in patients with type 2 diabetes, although TZDs may decrease visceral fat levels. Treatment with either metformin or TZDs was associated with a reduction in the risk of cardiovascular disease, although the mechanisms by which they accomplished this seem to differ. CONCLUSIONS: The evidence suggests that the predominant effect of metformin is inhibition of hepatic glucose production, whereas the primary effects of TZDs is reduction of insulin resistance and promotion of peripheral glucose uptake. TZDs appear to have more positive effects on other metabolic processes and to be associated with greater improvements in cardiovascular risk factors compared with metformin.

Cost effectiveness of combination therapy with pioglitazone for type 2 diabetes mellitus from a german statutory healthcare perspective.

BACKGROUND: Pioglitazone has been approved in Europe for oral combination therapy for type 2 diabetes mellitus. Along with other agents of the thiazolidinedione class, it has a novel intracellular mechanism of action. Clinical trials with pioglitazone have confirmed a strong product profile in terms of control of blood glucose and lipids. However, the drug acquisition cost for pioglitazone is greater than standard medications for type 2 diabetes. Long-term data regarding the cost effectiveness of pioglitazone-based combination therapy are not available. OBJECTIVE: To evaluate, using a decision analysis model, the cost effectiveness of pioglitazone-based combination therapy compared with relevant alternative medications for the treatment of type 2 diabetes in Germany. METHODS: This study compared the clinical effects and costs of pioglitazone 30 mg added to metformin in patients who failed metformin monotherapy and pioglitazone added to a sulphonylurea in patients who failed sulphonylurea monotherapy, with the most relevant treatment alternatives. A published and validated Markov model was adapted to reflect the management of type 2 diabetes. This simulated the number of severe complications occurring and the mean life expectancy of a diabetic cohort, which was based on the overweight group of the UK Prospective Diabetes Study at year 6 of follow-up. Drug treatment costs, other costs for general management of type 2 diabetes and the costs of complications were combined to compute overall lifetime treatment costs from the perspective of the German statutory healthcare system in 2002. RESULTS: Combination therapy with pioglitazone/metformin was associated with a higher life expectancy (15.2 years) relative to sulphonylurea/metformin (14.9 years) or acarbose/metformin (14.7 years). Likewise, pioglitazone/sulphonylurea (15.5 years) was superior to metformin/sulphonylurea (14.9 years) and acarbose/sulphonylurea (14.8 years). Undiscounted incremental cost-effectiveness ratios in comparison to the next best strategy were euro20,002 per life-year gained (LYG) for pioglitazone/metformin versus sulphonylurea/metformin, and euro8707 per LYG for pioglitazone/sulphonylurea versus metformin/sulphonylurea. After discounting costs and life expectancy at 5% per year, the incremental cost-effectiveness ratio was euro47 636 per LYG for pioglitazone/metformin versus sulphonylurea/metformin, and euro19 745 per LYG for pioglitazone/sulphonylurea versus metformin/sulphonylurea. CONCLUSIONS: In this model, with its underlying assumptions and data, combination therapy with pioglitazone increased life expectancy in overweight type 2 diabetes patients at acceptable cost compared with other well established medications in Germany. These findings should be re-evaluated as soon as additional evidence becomes available from the currently ongoing long-term clinical and economic studies.

Fasting intact proinsulin is a highly specific predictor of insulin resistance in type 2 diabetes.

OBJECTIVE: In later stages of type 2 diabetes, proinsulin and proinsulin-like molecules are secreted in increasing amounts with insulin. A recently introduced chemiluminescence assay is able to detect the uncleaved "intact" proinsulin and differentiate it from proinsulin-like molecules. This investigation explored the predictive value of intact proinsulin as an insulin resistance marker. RESEARCH DESIGN AND METHODS: In total, 48 patients with type 2 diabetes (20 women and 28 men, aged 60 +/- 9 years [means +/- SD], diabetes duration 5.1 +/- 3.8 years, BMI 31.2 +/- 4.8 kg/m2, and HbA1c 6.9 +/- 1.2%) were studied by means of an intravenous glucose tolerance test and determination of fasting values of intact proinsulin, insulin, resistin, adiponectin, and glucose. Insulin resistance was determined by means of minimal model analysis (MMA) (as the gold standard) and homeostatis model assessment (HOMA). RESULTS: There was a significant correlation between intact proinsulin values and insulin resistance (MMA P<0.05 and HOMA P<0.01). Elevation of intact proinsulin values above the reference range (>10 pmol/l) showed a very high specificity (MMA 100% and HOMA 92.9%) and a moderate sensitivity (MMA 48.6% and HOMA 47.1%) as marker for insulin resistance. Adiponectin values were slightly lower in the insulin resistant group, but no correlation to insulin resistance could be detected for resistin in the cross-sectional design. CONCLUSIONS: Elevated intact proinsulin seems to indicate an advanced stage of beta-cell exhaustion and is a highly specific marker for insulin resistance. It might be used as arbitrary marker for the therapeutic decision between secretagogue, sensitizer, or insulin therapy in type 2 diabetes.

IRIS II Study: Sensitivity and specificity of intact proinsulin, adiponectin, and the proinsulin/adiponectin ratio as markers for insulin resistance.

OBJECTIVE: This study was performed to compare the specificity and sensitivity of intact proinsulin, adiponectin, and their ratio (proinsulin/adiponectin) in the prediction of insulin resistance as assessed by the homeostasis model assessment (HOMA) score (> or =2 = resistant). RESEARCH DESIGN AND METHODS: Using a cross-sectional approach, 500 orally treated patients with type 2 diabetes (272 women, 238 men; mean +/- SD age, 64.8 +/- 11.6 years; hemoglobin A1c, 7.0 +/- 1.5%; disease duration, 5.8 +/- 6.1 years) were investigated. Various cutoffs for body mass index-adjusted adiponectin and proinsulin/adiponectin were compared with the established cutoff value of 10 pmol/L for fasting proinsulin. RESULTS: Fasting proinsulin correlated more closely with the HOMA score (r = 0.560, P < 0.001) than fasting adiponectin (r = -0.204, P < 0.001) or proinsulin/adiponectin (r = 0.355, P < 0.001). For proinsulin, specificity and sensitivity for insulin resistance in correlation to the HOMA score results were 96% and 70%, respectively. At a comparable specificity level to proinsulin, adiponectin did not reach a comparable sensitivity (14%), while the proinsulin/adiponectin ratio almost reached the same sensitivity (65%). Overall, patients with elevated proinsulin had a higher prevalence of micro- and macrovascular disease [odds ratio 1.47 (adiponectin, 1.08; proinsulin/ adiponectin, 1.48) and 1.34 (adiponectin, 1.32; proinsulin/adiponectin, 1.27), respectively]. CONCLUSIONS: Elevation of fasting intact proinsulin seems to be the more specific marker for insulin resistance and increased cardiovascular risk than suppression of fasting adiponectin. Formation of the ratio does not lead to a further increase in the predictive value.

Effects of pioglitazone on metabolic control and blood pressure: a randomised study in patients with type 2 diabetes mellitus.

AIM: This Swiss multicentre study examined the efficacy and safety of oral pioglitazone in patients with type 2 diabetes. METHODS: Patients were randomised to pioglitazone at once-daily doses of 30 mg for 20 weeks (n = 76), 30 mg for 12 weeks followed by 45 mg for 8 weeks (n = 74), or 45 mg for 20 weeks (n = 84); 94.9% of patients completed 12 weeks and 88.9% completed all 20 weeks. Almost all (96.6%) patients received pioglitazone in combination with other anti-diabetic treatments. RESULTS: Mean HbA(1c) at baseline was 8.8 +/- 1.2%, and changes to endpoint were -1.1 +/- 1.1%, -1.1 +/- 1.4% and -0.9 +/- 1.6%, respectively for the three dose groups ( p < 0.001 for each group). Triglyceride concentrations decreased in each group and the overall mean change during the study was -0.58 mmol/l (p < 0.001 versus baseline). HDL-cholesterol increased, with an overall mean change of 0.10 mmol/l (p < 0.001 versus baseline). Blood pressure decreased from baseline, particularly for hypertensive patients with mean changes: systolic -10 mmHg, p < 0.001, diastolic -8 mmHg, p < 0.001 versus baseline. Serum alanine aminotransferase and gamma-glutamyl transferase concentrations were significantly (p < 0.001 for each) reduced during the study. CONCLUSIONS: The study demonstrates the efficacy of pioglitazone 30 mg/day and 45 mg/day in the treatment of type 2 diabetes, with an improved lipid profile and decreased blood pressure in addition to improved glycaemic control.