Novel insulin sensitizers: pharmacogenomic aspects

Insulin resistance and Metabolic dysfunction-associated steatotic liver disease (MASLD): Pathways of action of hypoglycemic agents

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by overweight/obesity, and the presence of type 2 diabetes mellitus is the most important criterion. We propose an independent disease perspective without exclusion criteria and with less heterogeneity and greater impact because, according to the National Health and Nutrition Survey (ENSANUT), in Mexico, 25 % of adults over 60 years of age suffer from diabetes, and 96 % of those over 50 years of age have abdominal obesity. Due to the impact of insulin resistance in the pathophysiology of MASLD, which results in damage to hepatocytes, this work aims to provide an overview of the action pathways of hypoglycemic agents such as glucagon-like-1 receptor agonist and peroxisome proliferator-activated receptor-gamma agonists, whose importance lies in the fact that they are currently undergoing phase 2 studies, as well as dipeptidyl peptidase 4 inhibitors and sodium-glucose co-transporter type 2 inhibitors, which are undergoing phase 1 study trials.

Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes

Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.

Ursolic acid and rosiglitazone combination improves insulin sensitivity by increasing the skeletal muscle insulin-stimulated IRS-1 tyrosine phosphorylation in high-fat diet-fed C57BL/6J mice

The aim of this present study was to investigate the effect of ursolic acid (UA) and rosiglitazone (RSG) on insulin sensitivity and proximal insulin signaling pathways in high-fat diet (HFD)-fed C57/BL/6J mice. Male C57BL/6J mice were fed either normal diet or HFD for 10 weeks, after which animals in each dietary group were divided into the following six groups (normal diet, normal diet plus UA and RSG, HFD alone, HFD plus UA, HFD plus RSG, and HFD plus UA and RSG) for the next 5 weeks. UA (5 mg/kg BW) and RSG (4 mg/kg BW) were administered as suspensions directly into the stomach using a gastric tube. The HFD diet elevated fasting plasma glucose, insulin, and homeostasis model assessment index. The expression of insulin receptor substrate (IRS)-1, phosphoinositide 3-kinase (PI3-kinase), Akt, and glucose transporter (GLUT) 4 were determined by Western blot analyses. The results demonstrated that combination treatment (UA/RSG) ameliorated HFD-induced glucose intolerance and insulin resistance by improving the homeostatic model assessment (HOMA) index. Further, combination treatment (UA/RSG) stimulated the IRS-1, PI3-kinase, Akt, and GLUT 4 translocation. These results strongly suggest that combination treatment (UA/RSG) activates IRS-PI3-kinase-Akt-dependent signaling pathways to induce GLUT 4 translocation and increases the expression of insulin receptor to improve glucose intolerance.

Genetic and epigenetic control of metabolic health

Obesity is characterized as an excess accumulation of body fat resulting from a positive energy balance. It is the major risk factor for type 2 diabetes (T2D). The evidence for familial aggregation of obesity and its associated metabolic diseases is substantial. To date, about 150 genetic loci identified in genome-wide association studies (GWAS) are linked with obesity and T2D, each accounting for only a small proportion of the predicted heritability. However, the percentage of overall trait variance explained by these associated loci is modest (~5-10% for T2D, ~2% for BMI). The lack of powerful genetic associations suggests that heritability is not entirely attributable to gene variations. Some of the familial aggregation as well as many of the effects of environmental exposures, may reflect epigenetic processes. This review summarizes our current knowledge on the genetic basis to individual risk of obesity and T2D, and explores the potential role of epigenetic contribution.

Individualized therapy for type 2 diabetes: clinical implications of pharmacogenetic data

Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance, abnormally elevated hepatic glucose production, and reduced glucose-stimulated insulin secretion. Treatment with antihyperglycemic agents is initially successful in type 2 diabetes, but it is often associated with a high secondary failure rate, and the addition of insulin is eventually necessary for many patients, in order to restore acceptable glycemic control and to reduce the risk of development and progression of disease complications. Notably, even patients who appear to have similar requirements of antidiabetic regimens show great variability in drug disposition, glycemic response, tolerability, and incidence of adverse effects during treatment. Pharmacogenomics is a promising area of investigation and involves the search for genetic polymorphisms that may explain the interindividual variability in antidiabetic therapy response. The initial positive results portend that genomic efforts will be able to shed important light on variability in pharmacologic traits. In this review, we summarize the current understanding of genetic polymorphisms that may affect the responses of subjects with T2DM to antidiabetic treatment. These genes belong to three major classes: genes involved in drug metabolism and transporters that influence pharmacokinetics (including the cytochrome P450 [CYP] superfamily, the organic anion transporting polypeptide [OATP] family, and the polyspecific organic cation transporter [OCT] family); genes encoding drug targets and receptors (including peroxisome proliferator-activated receptor gamma [PPARG], the adenosine triphosphate [ATP]-sensitive potassium channel [K(ATP)], and incretin receptors); and genes involved in the causal pathway of T2DM that are able to modify the effects of drugs (including adipokines, transcription factor 7-like 2 (T cell specific, HMG-box) [TCF7L2], insulin receptor substrate 1 [IRS1], nitric oxide synthase 1 (neuronal) adaptor protein [NOS1AP], and solute carrier family 30 (zinc transporter), member 8 [SLC30A8]). In addition to these three major classes, we also review the available evidence on novel genes (CDK5 regulatory subunit associated protein 1-like 1 [CDKAL1], insulin-like growth factor 2 mRNA binding protein 2 [IGF2BP2], potassium voltage-gated channel, KQT-like subfamily, member 1 [KCNQ1], paired box 4 [PAX4] and neuronal differentiation 1 [NEUROD1] transcription factors, ataxia telangiectasia mutated [ATM], and serine racemase [SRR]) that have recently been proposed as possible modulators of therapeutic response in subjects with T2DM.

Pharmacogenetics of Anti-Diabetes Drugs

A variety of treatment modalities exist for individuals with type 2 diabetes mellitus (T2D). In addition to dietary and physical activity interventions, T2D is also treated pharmacologically with nine major classes of approved drugs. These medications include insulin and its analogues, sulfonylureas, biguanides, thiazolidinediones (TZDs), meglitinides, α-glucosidase inhibitors, amylin analogues, incretin hormone mimetics, and dipeptidyl peptidase 4 (DPP4) inhibitors. Pharmacological treatment strategies for T2D are typically based on efficacy, yet favorable responses to such therapeutics are oftentimes variable and difficult to predict. Characterization of drug response is expected to substantially enhance our ability to provide patients with the most effective treatment strategy given their individual backgrounds, yet pharmacogenetic study of diabetes medications is still in its infancy. To date, major pharmacogenetic studies have focused on response to sulfonylureas, biguanides, and TZDs. Here, we provide a comprehensive review of pharmacogenetics investigations of these specific anti-diabetes medications. We focus not only on the results of these studies, but also on how experimental design, study sample issues, and definition of 'response' can significantly impact our interpretation of findings. Understanding the pharmacogenetics of anti-diabetes medications will provide critical baseline information for the development and implementation of genetic screening into therapeutic decision making, and lay the foundation for "individualized medicine" for patients with T2D.

Thiazolidinediones and antiblastics in primary human anaplastic thyroid cancer cells

OBJECTIVE

No study has evaluated the antiproliferative effects of thiazolidinediones and antiblastics in 'primary cultured human anaplastic thyroid cancer cells'.

DESIGN

Primary anaplastic cells proliferation was evaluated after incubation with increasing concentrations of rosiglitazone or pioglitazone or antiblastics (bleomycin, cisplatin, gemcitabine) by a proliferation assay (WST-1-tetrazolium reaction) and cell counting.

MEASUREMENTS AND RESULTS

A reduction of proliferation by thiazolidinediones at 1 h (from the start of tetrazolium reaction) [of 11% and 25%, with rosiglitazone, 10 or 20 (P = 0.0001) microM, respectively; of 7% and 17%, with pioglitazone, 10 or 20 (P = 0.0125) microM, respectively], and at 2 h [of 14% and 24%, with rosiglitazone, 10 (P = 0.0043) or 20 (P < 0.0001) microM, respectively; of 9% and 21%, with pioglitazone, 10 (P = 0.0397) or 20 (P = 0.0001) microM, respectively] was shown. No significant thiazolidinediones effect was observed in normal thyroid follicular cells. Bleomycin, cisplatin and gemcitabine significantly (P < 0.0001) inhibited (> 50%) anaplastic cells proliferation. Cell counting confirmed the above mentioned results. Inhibition of proliferation was similar in tumours with or without (V600E)BRAF mutation, both for thiazolidinediones and antiblastics.

CONCLUSIONS

Thiazolidinediones exert an antiproliferative effect in primary cultured human anaplastic carcinoma cells in vitro, such as antiblastics.

Berberine reduces insulin resistance through protein kinase C-dependent up-regulation of insulin receptor expression

Natural product berberine (BBR) has been reported to have hypoglycemic and insulin-sensitizing activities; however, its mechanism remains unclear. This study was designed to investigate the molecular mechanism of BBR against insulin resistance. Here, we identify insulin receptor (InsR) as a target of BBR to increase insulin sensitivity. In cultured human liver cells, BBR increased InsR messenger RNA (mRNA) and protein expression in a dose- and time-dependent manner. Berberine increased InsR expression in the L6 rat skeletal muscle cells as well. Berberine-enhanced InsR expression improved cellular glucose consumption only in the presence of insulin. Silencing InsR gene with small interfering RNA or blocking the phosphoinositol-3-kinase diminished this effect. Berberine induced InsR gene expression through a protein kinase C (PKC)-dependent activation of its promoter. Inhibition of PKC abolished BBR-caused InsR promoter activation and InsR mRNA transcription. In animal models, treatment of type 2 diabetes mellitus rats with BBR lowered fasting blood glucose and fasting serum insulin, increased insulin sensitivity, and elevated InsR mRNA as well as PKC activity in the liver. In addition, BBR lowered blood glucose in KK-Ay type 2 but not in NOD/LtJ type 1 diabetes mellitus mice that were insulin deficient. Our results suggest that BBR is a unique natural medicine against insulin resistance in type 2 diabetes mellitus and metabolic syndrome.

Pharmacogenetics of the PPAR genes and cardiovascular disease

The goal of pharmacogenetics is to define the genetic determinants of individual drug responsiveness, and thereby provide personalized treatment to each individual. The peroxisome proliferator-activated receptors (PPARs) are polypeptide products of a set of related genes functioning to regulate several cellular processes that are central to cardiovascular health and disease. Given their pleiotropic roles in lipid and glucose homeostasis, cardiac energy balance and regulation of adipocyte release of circulating inflammatory factors, it is not surprising that PPARs represent an attractive target for clinical investigation and intervention in disease states, such as diabetes, obesity, atherosclerosis, cardiomyopathy, cardiac hypertrophy and heart failure. Research into the manipulation of PPAR function by pharmacologic agents has already resulted in important advances in the treatment of diabetes mellitus and cardiovascular disease. It follows that PPAR pharmacogenetics promises important advances in the personalized treatment of cardiovascular disease.

Pharmacogenetics of thiazolidinedione therapy

The thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor-γ agonists and have glucose-lowering, insulin-sensitizing and anti-inflammatory effects. TZDs are approved for the treatment of Type 2 diabetes, and have been studied as a diabetes-prevention strategy. Despite widespread use of TZDs, a large number of patients fail to achieve a substantial reduction in glucose, or an improvement in insulin sensitivity, following treatment. Available data suggest that polymorphisms in genes encoding TZD drug targets, effector proteins and metabolizing enzymes contribute to the observed interindividual variability in TZD response and disposition. The purpose of this review is to highlight recent developments in the field of TZD pharmacogenetics, specifically focusing on clinical studies that have investigated genetic determinants of TZD response (i.e., reduction in glycemia and improvement in insulin sensitivity), disposition (i.e., pharmacokinetics), and side effects in patients with Type 2 diabetes and patients at risk for Type 2 diabetes.

The PPAR genes, cardiovascular disease and the emergence of PPAR pharmacogenetics

The peroxisome proliferator-activated receptors (PPARs) comprise a group of related transcription factors that serve to regulate a number of cellular processes that are central to cardiovascular health and disease. Two large bodies of work strongly implicate the PPARs as key factors in normal cardiovascular physiology and in cardiovascular pathophysiology: i) studies demonstrating associations between PPAR and abnormal cardiovascular phenotypes; and ii) pharmacological studies assessing the effects of specific PPAR agonists in clinical trials. With the abundance of data available from these studies as a background, PPAR pharmacogenetics has become a promising and rapidly-advancing field. This review summarises the current state of understanding of PPAR pharmacogenetics and its profound implications for the individualisation of therapy for patients with a diverse group of cardiovascular diseases.

PNU-91325 increases fatty acid synthesis from glucose and mitochondrial long chain fatty acid degradation: a comparative tracer-based metabolomics study with rosiglitazone and pioglitazone in HepG2 cells

The mitochondrial membrane protein termed "mitoNEET," is a putative secondary target for insulin-sensitizing thiazolidinedione (TZD) compounds but its role in regulating metabolic flux is not known. PNU-91325 is a thiazolidinedione derivative which exhibits high binding affinity to mitoNEET and lowers cholesterol, fatty acid and blood glucose levels in animal models. In this study we report the stable isotope-based dynamic metabolic profiles (SIDMAP) of rosiglitazone, pioglitazone and PNU-91325 in a dose-matching, dose-escalating study. One and 10 μM concentrations 1 and 10 μM drug concentrations were introduced into HepG2 cells in the presence of either [1,2-13C2]-D-glucose or [U-13C18]stearate, GC/MS used to determine positional tracer incorporation (mass isotopomer analysis) into multiple metabolites produced by the Krebs and pentose cycles, de novo fatty acid synthesis, long chain fatty acid oxidation, chain shortening and elongation. Rosiglitazone and pioglitazone (10 μM) increased pentose synthesis from [U-13C18]stearate by 127% and 185%, respectively, while PNU-91325 rather increased glutamate synthesis in the Krebs cycle by 113% as compared to control vehicle treated cells. PNU-91325 also increased stearate chain shortening into palmitate by 59%. Glucose tracer-derived de novo palmitate and stearate synthesis were increased by 1 and 10 μM rosiglitazone by 41% and 83%, respectively, and by 63% and 75% by PNU-91325. Stearate uptake was also increased by 10 μM PNU-91325 by 15.8%. We conclude that the entry of acetyl Co-A derived from long-chain fatty acid β-oxidation into the mitochondria is facilitated by the mitoNEET ligand PNU-91325, which increases glucose-derived long chain fatty acid synthesis and breakdown via β-oxidation and anaplerosis in the mitochondria.

PPAR-gamma: a nuclear receptor with affinity for cannabinoids

An increasing number of cannabinoid actions are being reported that do not appear to be mediated by either CB1 or CB2, the known cannabinoid receptors. One such example is the synthetic analog ajulemic acid (AJA), which shows potent analgesic and anti-inflammatory effects in rodents and humans. AJA binds weakly to CB1 only at concentrations many fold higher than its therapeutic range, and is, therefore, completely free of psychotropic effects in both normal subjects and pain patients suggesting the involvement of a target site other than CB1. AJA as well as several other cannabinoids appear to have profound effects on cellular lipid metabolism as evidenced by their ability to transform fibroblasts into adipocytes where the accumulation of lipid droplets can be readily observed. Such transformations can be mediated by the activation of the nuclear receptor PPAR-gamma. A variety of small molecule ligands including AJA have been shown to induce the activation of PPAR-gamma and, in some cases this has led to the introduction of clinically useful agents. It is suggested that PPAR-gamma may serve a receptor function for certain actions of some cannabinoids.

Sequence variation in PPARG may underlie differential response to troglitazone

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor-gamma (PPARG) agonists used to treat type 2 diabetes. TZDs can also be used to reduce rates of type 2 diabetes in at-risk individuals. However, a large fraction of TZD-treated patients (30-40%) do not respond to TZD treatment with an improvement in insulin sensitivity (Si). We hypothesized that variation within the gene encoding PPARG may underlie this differential response to TZD therapy. We screened approximately 40 kb of PPARG in 93 nondiabetic Hispanic women (63 responders and 30 nonresponders) with previous gestational diabetes who had participated in the Troglitazone In the Prevention Of Diabetes study. TZD nonresponse was defined as the lower tertile in change in Si after 3 months of treatment. Baseline demographic and clinical measures were not different between responders and nonresponders. We identified and genotyped 131 variants including 126 single nucleotide polymorphisms and 5 insertion-deletion polymorphisms. Linkage disequilibrium analysis identified five haplotype blocks. Eight variants were associated with TZD response (P < 0.05). Three variants were also associated with changes in Si as a continuous variable. Our results suggest that PPARG variation may underlie response to TZD therapy in women at risk for type 2 diabetes.

Effect of ketoconazole on the pharmacokinetics of rosiglitazone in healthy subjects

AIMS

Fungal infection is a significant comorbidity in patients with diabetes mellitus, and ketoconazole, an antifungal agent, causes a number of drug interactions with coadministered drugs. Rosiglitazone is a novel thiazolidinedione antidiabetic drug, mainly metabolized by CYP2C8 and to a lesser extent CYP2C9. We investigated the possible effect of ketoconazole on the pharmacokinetics of rosiglitazone in humans.

METHODS

Ten healthy Korean male volunteers were treated twice daily for 5 days with 200 mg ketoconazole or with placebo, using a randomized, open-label, two-way crossover study. On day 5, a single dose of 8 mg rosiglitazone was administered orally, and plasma rosiglitazone concentrations were measured.

RESULTS

Ketoconazole increased the mean area under the plasma concentration-time curve for rosiglitazone by 47%[P = 0.0003; 95% confidence interval (CI) 23, 70] and the mean elimination half-life from 3.55 to 5.50 h (P = 0.0003; 95% CI in difference 1.1, 2.4). The peak plasma concentration of rosiglitazone was increased by ketoconazole treatment by 17% (P = 0.03; 95% CI 5, 29). The apparent oral clearance of rosiglitazone decreased by 28% after ketoconazole treatment (P = 0.0005; 95% CI 18, 38).

CONCLUSIONS

This study revealed that ketoconazole affected the disposition of rosiglitazone in humans, probably by the inhibition of CYP2C8 and CYP2C9, leading to increasing rosiglitazone concentrations that could increase the efficacy of rosiglitazone or its adverse events.

Identification of oral antidiabetics and their metabolites in human urine by liquid chromatography/tandem mass spectrometry--a matter for doping control analysis

Since 1999, insulin belongs to the list of prohibited substances of the International Olympic Committee and the World Anti-Doping Agency. Except for patients suffering from insulin-dependent diabetes mellitus, the administration of insulin is not allowed. Therapeutics developed to treat non-insulin-dependent diabetes mellitus act as releasing factors of endogenously produced insulin or improve its efficiency mediating the glucose uptake into insulin-dependent tissues. Hence, these compounds are also relevant for sports drug testing, and a fast, robust, and sensitive assay was developed to identify 12 oral antidiabetic agents or respective hydroxylated metabolites in human urine. Urine specimens are enzymatically hydrolyzed; target analytes are extracted by liquid-liquid extraction and identified by means of liquid chromatography interfaced to tandem mass spectrometry by electrospray ionization. Detection limits of respective drugs ranged between 10 and 30 ng/mL, metabolites of therapeutics were characterized by diagnostic fragmentation pathways upon collisionally activated dissociation of protonated molecules, and general fragmentation routes were proposed.

Signaling pathways involved in induction of GADD45 gene expression and apoptosis by troglitazone in human MCF-7 breast carcinoma cells

We previously reported that the PPARgamma agonist troglitazone (TRO) inhibits proliferation and induces apoptosis in human MCF-7 breast carcinoma cells. To understand the mechanisms of antiproliferative and pro-apoptotic effects of TRO, we screened a limited DNA array containing 23 genes involved in regulating either the cell cycle and/or apoptosis. Four of the 23 genes screened exhibited regulation by TRO, with growth arrest and DNA damage-inducible gene 45 (GADD45) being the most strongly upregulated. TRO induced GADD45 mRNA expression in a time- and dose-dependent manner. Depletion of GADD45 by siRNA abrogated TRO-induced apoptosis in MCF-7 cells demonstrating the physiological relevance of GADD45 upregulation. Signaling pathways mediating TRO-induced GADD45 were also investigated. Several mitogen-activated protein kinase (MAPK) pathways were involved in the induction of GADD45 by TRO. Inhibition of the c-jun N-terminal kinase MAPK pathway by SP600125 partially abolished TRO-induced GADD45 mRNA, and protein expression and apoptosis. In contrast, inhibition of the p38 MAPK pathway by SB203580, or through overexpression of a dominant-negative mutant of p38 MAPK, augmented GADD45 mRNA induction and GADD45 promoter activation as well as cell apoptosis by TRO. Blockade of the extracellular signal-regulated kinase MAPK pathway by PD98059 also enhanced TRO's effects on GADD45 and apoptosis. Two other PPARgamma agonists pioglitazone and rosiglitazone did not induce GADD45 expression. Our finding of GADD45 induction by TRO may provide a new insight concerning the mechanisms for TRO's antiproliferative and pro-apoptotic effects in breast cancer cells.

Thiazolidinediones increase arachidonic acid release and subsequent prostanoid production in a peroxisome proliferator-activated receptor γ-independent manner

Thiazolidinedione, peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, has been used as an anti-diabetic drug and as an useful tool to elucidate multiple PPARgamma functions by in vitro and in vivo studies. We investigated the effects of thiazolidinediones on prostanoid production in lipopolysaccharide-stimulated cells. The high concentrations (>10 microM) of rosiglitazone and pioglitazone significantly increased lipopolysaccharide-stimulated prostanoid production such as thromboxane A2 and prostaglandin E2. However, PPARgamma antagonist could not inhibit them. In PPARgamma-deficient cells, thiazolidinediones increased prostaglandin E2 production. Thiazolidinediones increased arachidonic acid (AA) release from the cell membrane by not stimulating AA releasing process involving several phospholipase A2s but inhibiting AA reuptaking process. The expression of cyclooxygenase-1 and cyclooxygenase-2 were not affected by thiazolidinediones. In this study, we demonstrated that high concentrations of TZDs increased AA release by the inhibition of AA reuptaking process, leading to subsequent increase in the prostanoid production in a PPARgamma-independent manner. This mechanism provides useful information for the elucidation of multiple PPARgamma functions and diabetic drug therapy.

Prevention of autoimmune diabetes in NOD mice by troglitazone is associated with modulation of ICAM-1 expression on pancreatic islet cells and IFN-gamma expression in splenic T cells

Thiazolidinediones acting as PPAR-gamma agonists are a new generation of oral antidiabetics addressing insulin resistance as a main feature of type-2 diabetes. In accordance to our results, pre-clinical studies have demonstrated that the thiazolinedione troglitazone prevents the development of insulin-dependent autoimmune type-1 diabetes. To investigate whether TGZ acts by affecting the ICAM-1/LFA-1 pathway and/or the Th1/Th2 cytokine balance in NOD mice, we analysed the IL-1beta-induced ICAM-1 expression on islet-cells and the LFA-1, CD25, IL-2, IFN-gamma, IL-4, and IL-10 expression on splenocytes. After 200 days of oral TGZ administration, islet cells from TGZ-treated NOD mice showed a reduced ICAM-1 expression in response to the pro-inflammatory cytokine IL-1beta. The expression of the ligand LFA-1 on CD4(+) and CD8(+) T-cells was comparable to that of placebo- and untreated controls. Also, the expression of Th1/Th2 cytokines was comparable in groups receiving TGZ or Placebo. Nevertheless, the investigated NOD mice segregated into IFN-gamma low- and IFN-gamma high producers as revealed by cluster analysis. Interestingly, the majority of TGZ-treated mice belonged to the cluster of IFN-gamma low producers. Thus, the prevention of autoimmune diabetes in NOD mice by TGZ seems to be associated with suppression of IL-1beta-induced ICAM-1 expression leading to a reduced vulnerability of pancreatic beta-cells during the effector stage of beta-cell destruction. In addition, IFN-gamma production was modulated, implicating that alteration of the Th1/Th2 cytokine balance might have contributed to diabetes prevention. The findings of this study suggest that TGZ exerts its effects by influencing both the beta-cells as the target of autoimmune beta-cell destruction and the T-cells as major effectors of the autoimmune process.

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.

Improved Glycemic Control and Lipid Profile in a Randomized Study of Pioglitazone Compared with Acarbose in Patients with Type 2 Diabetes Mellitus

OBJECTIVE

To assess the efficacy of pioglitazone treatment in comparison with that of acarbose treatment in patients with type 2 diabetes mellitus.

PARTICIPANTS AND METHODS

In this randomized, parallel-group, open-label study patients were assigned to treatment with either pioglitazone (n = 129) or acarbose (n = 136). During a 1-week run-in patients commenced an individualized dietary regimen which was maintained throughout the study. Patients received the assigned study medication for 26 weeks. Serum glycosylated hemoglobin (HbA1c) levels, insulin resistance and lipid profiles were determined at baseline and at endpoint.

RESULTS

Mean HbA1c was reduced from 8.98+/-1.20% to 7.82+/-1.95% with pioglitazone treatment and from 9.03+/-1.32% to 8.55+/-1.96% with acarbose treatment during the 26-week study. The change from baseline to endpoint was significantly greater for pioglitazone compared with acarbose when analyzed for all patients (p < 0.001) and for those who had (p = 0.009) or had not (p < 0.001) received previous medication for diabetes mellitus. Compared with acarbose, pioglitazone produced a significantly greater decrease in fasting glucose, insulin and insulin resistance (p < 0.001 for each). Triglycerides were decreased by 71.1+/-184.1 mg/dl with pioglitazone compared with 38.1+/-171.3 mg/dl with acarbose (p = 0.001 for difference between groups). High density lipoprotein (HDL)-cholesterol level was increased by 7.8+/-10.2 mg/dl with pioglitazone compared with a decrease of 0.8+/-24.1 mg/dl with acarbose (p < 0.001). While serum low density lipoprotein (LDL)-cholesterol levels remained unchanged with both treatment regimens, the decrease from baseline in very low density lipoprotein (VLDL)-cholesterol was significantly greater with pioglitazone than with acarbose (p < 0.04). Pioglitazone decreased systolic blood pressure by 5.6+/-17.7mm Hg compared with a 0.4+/-18.4mm Hg increase during acarbose treatment (p < 0.001). Pioglitazone caused a significantly greater decrease compared with acarbose in serum levels of gamma-glutamyl aminotransferase (p < 0.001) and alanine aminotransferase (p = 0.004).

CONCLUSIONS

Six months of pioglitazone treatment decreased insulin resistance and improved glycemic control to a significantly greater extent than acarbose treatment. Pioglitazone was also associated with a significantly improved lipid profile, suggesting a reduction in risk of coronary heart disease.