Treatment with pioglitazone is associated with decreased preprandial ghrelin levels: a randomized clinical trial

Effects of pioglitazone treatment on blood leptin levels in patients with type 2 diabetes

AIMS/INTRODUCTION

The aim of the present study was to carry out a meta-analysis of randomized controlled trials (RCTs) that investigated the effects of pioglitazone on blood leptin levels in patients with type 2 diabetes.

MATERIALS AND METHODS

Literature searches were carried out using Medline, the Cochrane Controlled Trials Registry and ClinicalTrials.gov, and RCTs that investigated the effects of pioglitazone on blood leptin levels in patients with type 2 diabetes were selected. Standardized mean differences and 95% confidence intervals were calculated.

RESULTS

A total of 10 RCTs met the eligibility criteria and were included in the meta-analysis. Significantly lower blood leptin levels were observed in the pioglitazone group (standardized mean difference -0.58, 95% confidence interval -1.12 to -0.05%, P = 0.03) than in the placebo group. There was no significant difference in blood leptin levels observed between the pioglitazone and oral antidiabetic drug groups (standardized mean difference -0.01, 95% confidence interval -0.20 to 0.19%, P = 0.93).

CONCLUSIONS

There was a significant difference in blood leptin levels between the pioglitazone and placebo groups. However, relatively few RCTs were included in the study, and there was a high level of statistical heterogeneity; we believe that this could have affected the results.

Effects of metformin treatment on blood leptin and ghrelin levels in patients with type 2 diabetes mellitus

BACKGROUND

The aim of the present study was to conduct a meta-analysis of randomized controlled trials (RCTs) that investigated the effects of metformin on blood leptin and ghrelin levels in patients with type 2 diabetes mellitus (T2DM).

METHODS

Literature searches were performed using MEDLINE, Cochrane Controlled Trials Registry, and ClinicalTrials.gov, and RCTs that investigated the effects of metformin on blood leptin and ghrelin levels in patients with T2DM were selected. Standardized mean differences (SMDs) and 95 % confidence intervals (CIs) were calculated.

RESULTS

Twelve RCTs met the eligibility criteria and were included in the meta-analysis. There was no significant difference in blood leptin between the metformin and control groups (SMD 0.03; 95 % CI -0.35 %, 0.42 %; P = 0.86), although there was a significant difference in blood leptin levels between the metformin group and the group on oral antidiabetic drugs (OADs) other than metformin (SMD -0.39; 95 % CI -0.76 %, -0.01 %; P = 0.04). There were no significant differences in blood ghrelin levels.

CONCLUSIONS

Metformin treatment was not associated with a decrease in blood leptin levels in patients with T2DM compared with levels in patients in the control group. Moreover, metformin treatment was not associated with increases in blood ghrelin levels compared with the control and other OADs groups. However, blood leptin levels were significantly lower in the metformin compared with the other OADs group.

Protective effect of boswellic acids versus pioglitazone in a rat model of diet-induced non-alcoholic fatty liver disease: influence on insulin resistance and energy expenditure

Non-alcoholic fatty liver disease (NAFLD) is closely linked to insulin resistance, oxidative stress, and cytokine imbalance. Boswellic acids, a series of pentacyclic triterpene molecules that are produced by plants in the genus Boswellia, has been traditionally used for the treatment of a variety of diseases. This study aimed at evaluating the protective effect of boswellic acids in a model of diet-induced NAFLD in rats in comparison to the standard insulin sensitizer, pioglitazone. Rats were fed with a high-fat diet (HFD) for 12 weeks to induce NAFLD. Starting from week 5, rats received boswellic acids (125 or 250 mg/kg) or pioglitazone parallel to the HFD. Feeding with HFD induced hepatic steatosis and inflammation in rats. In addition, liver index, insulin resistance index, activities of liver enzymes, and serum lipids deviated from normal. Further, serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and cyclooxygenase 2 were elevated; this was associated with an increase in hepatic expression of inducible nitric oxide synthase (iNOS) and formation of 4-hydroxy-2-nonenal (HNE). Rats treated with boswellic acids (125 or 250 mg/kg) or pioglitazone showed improved insulin sensitivity and a reduction in liver index, activities of liver enzymes, serum TNF-α and IL-6 as well as hepatic iNOS expression and HNE formation compared to HFD group. Furthermore, at the cellular level, boswellic acids (250 mg/kg) ameliorated the expression of thermogenesis-related mitochondrial uncoupling protein-1 and carnitine palmitoyl transferase-1 in white adipose tissues. Data from this study indicated that boswellic acids might be a promising therapy in the clinical management of NAFLD if appropriate safety and efficacy data are available.

Liraglutide reduces oxidative stress and restores heme oxygenase-1 and ghrelin levels in patients with type 2 diabetes: a prospective pilot study

CONTEXT

Liraglutide is a glucagon-like peptide-1 analog and glucose-lowering agent whose effects on cardiovascular risk markers have not been fully elucidated.

OBJECTIVE

We evaluated the effect of liraglutide on markers of oxidative stress, heme oxygenase-1 (HO-1), and plasma ghrelin levels in patients with type-2 diabetes mellitus (T2DM).

DESIGN AND SETTING

A prospective pilot study of 2 months' duration has been performed at the Unit of Diabetes and Cardiovascular Prevention at University of Palermo, Italy. Patients and Intervention(s): Twenty subjects with T2DM (10 men and 10 women; mean age: 57 ± 13 y) were treated with liraglutide sc (0.6 mg/d for 2 wk, followed by 1.2 mg/d) in addition to metformin (1500 mg/d orally) for 2 months. Patients with liver disorders or renal failure were excluded.

MAIN OUTCOME MEASURE(S)

Plasma ghrelin concentrations, oxidative stress markers, and heat-shock proteins, including HO-1 were assessed.

RESULTS

The addition of liraglutide resulted in a significant decrease in glycated hemoglobin (HbA1c) (8.5 ± 0.4 vs 7.5 ± 0.4%, P < .0001). In addition, plasma ghrelin and glutathione concentrations increased (8.2 ± 4.1 vs 13.6 ± 7.3 pg/ml, P = .0007 and 0.36 ± 0.06 vs 0.44 ± 0.07 nmol/ml, P = .0002, respectively), whereas serum lipid hydroperoxides and HO-1 decreased (0.11 ± 0.05 vs 0.04 ± 0.07 pg/ml, P = .0487 and 7.7 ± 7.7 vs 3.6 ± 1.8 pg/ml, P = .0445, respectively). These changes were not correlated with changes in fasting glycemia or HbA1c.

CONCLUSIONS

In a 2-months prospective pilot study, the addition of liraglutide to metformin resulted in improvement in oxidative stress as well as plasma ghrelin and HO-1 concentrations in patients with T2DM. These findings seemed to be independent of the known effects of liraglutide on glucose metabolism.