The effect of pioglitazone as add-on therapy to metformin or sulphonylurea compared to a fixed-dose combination of metformin and glibenclamide on diabetic dyslipidaemia

Cardiovascular safety and efficacy of metformin-SGLT2i versus metformin-sulfonylureas in type 2 diabetes: systematic review and meta-analysis of randomized controlled trials

Diabetes is a serious threat to global health and among the top 10 causes of death, with nearly half a billion people living with it worldwide. Treating patients with diabetes tend to become more challenging due to the progressive nature of the disease. The role and benefits of combination therapies for the management of type 2 diabetes are well-documented, while the comparative safety and efficacy among the different combination options have not been elucidated. We aimed to systematically synthesize the evidence on the comparative cardiovascular safety and efficacy of combination therapy with metformin-sodium-glucose cotransporter-2 inhibitors versus metformin-sulfonylureas in patients with type 2 diabetes. We searched MEDLINE-PubMed, Embase, Cochrane Library, and ClinicalTrials.gov up to 15 August 2019 without restriction in the year of publication. We included randomized controlled trials of patients with type 2 diabetes who were on metformin-sodium-glucose cotransporter-2 inhibitors or metformin-sulphonylureas combination therapy at least for a year. The primary endpoints were all-cause mortality and serious adverse events, and the secondary endpoints were cardiovascular mortality, non-fatal myocardial infarction, non-fatal stroke, hypoglycemia, and changes in glycated hemoglobin A1c (HbA1c), body weight, fasting plasma glucose, blood pressure, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. We used a random-effects meta-analysis model to estimate mean differences for continuous outcomes and risk ratio for dichotomous outcomes. We followed PICOS description model for defining eligibility and the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 guidelines for reporting results. Of 3,190 citations, we included nine trials involving 10,974 participants. The pooled analysis showed no significant difference in all-cause mortality (risk ration [RR] = 0.93, 95% CI [0.52, 1.67]), serious adverse events (RR = 0.96, 95% CI [0.79, 1.17]) and adverse events (RR = 1.00, 95% CI [0.99, 1.02]) between the two, but in hypoglycemia (RR = 0.13, 95% CI [0.10, 0.17], P < 0.001). Participants taking metformin-sodium glucose cotransporter-2 inhibitors showed a significantly greater reduction in HbA1c (mean difference [MD] = − 0.10%, 95% CI [− 0.17, − 0.03], body weight (MD = − 4.57 kg, 95% CI [− 4.74, − 4.39], systolic blood pressure (MD = − 4.77 mmHg, 95% CI [− 5.39, − 4.16]), diastolic blood pressure (MD = − 2.07 mmHg, 95% CI [− 2.74, − 1.40], and fasting plasma glucose (MD = − 0.55 mmol/L, 95% CI [− 0.69, − 0.41]), p < 0.001. Combination therapy of metformin and sodium-glucose cotransporter-2 inhibitors is a safe and efficacious alternative to combination therapy of metformin and sulphonylureas for patients with type 2 diabetes who are at risk of cardiovascular comorbidity. However, there remains a need for additional long-term randomized controlled trials as available studies are very limited and heterogeneous.

Adequacy of clinical trial evidence of metformin fixed-dose combinations for the treatment of type 2 diabetes mellitus in India

There is growing national and international concern about the drug regulatory system in India. Parliamentary reports have highlighted the presence of high numbers of unapproved medicines and irrational combinations of both approved and unapproved drugs in the Indian market-place. Fixed-dose combinations (FDCs) are a peculiar feature of the Indian pharmaceutical landscape. Although metformin is a first-line treatment, FDCs for diabetes in India account for two-thirds of all diabetes medicine sales, and some have not been approved by the Central Drugs Standard Control Organization (CDSCO). This study examines the basis of efficacy and safety of top-selling metformin FDCs in India against four WHO criteria from clinical trials guidelines for the approval of FDCs. Data from a commercial drug sales database (PharmaTrac) were combined with searches through published literature, clinical trial registries, and published and unpublished trial websites of metformin FDCs in adults with type 2 diabetes mellitus. Five metformin FDCs in India from November 2011 to October 2012 accounted for 80% of all metformin FDC sales by value and volume. Although all five had obtained CDSCO approval, three had been sold and marketed prior to receiving this approval. Evaluation of published and unpublished clinical trials of these five FDCs found none provided robust evidence of safety and efficacy for the treatment of type 2 diabetes. Recommendations are made for publishing evidence that underpins drug approvals, marketing bans, greater transparency through updated clinical trials databases and legislative reform in order to prevent irrational FDCs from entering the market.

The effect of a dual combination of noninsulin antidiabetic drugs on lipids: a systematic review and network meta-analysis

OBJECTIVE

As an ever widening array of anti-hyperglycemic agents are now available, the effect of these drugs on lipids is increasingly complex and controversial. The present meta-analysis was designed to clarify the effect of a dual combination of noninsulin anti-hyperglycemic agents on lipids in type 2 diabetes.

METHODS

Randomized controlled trials comparing different dual combinations of antidiabetic drugs were identified by searching PubMed, Cochrane Library, and Embase. Study selection, data abstraction and quality assessment were carried out by two reviewers independently. Change in low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride and total cholesterol were pooled by both traditional meta-analysis and network meta-analysis.

RESULTS

Eighteen studies with a total of 10,222 patients were included. Network meta-analysis suggested that metformin + dipeptidyl peptidase-4 inhibitors (DPP-4) (LDL cholesterol: -0.19 mmol/L; HDL cholesterol: 0.06 mmol/L; triglycerides: -0.73 mmol/L; total cholesterol: -0.4 mmol/L) and metformin + glucagon-like peptide-1 (GLP-1) agonist (LDL cholesterol: -0.3 mmol/L; HDL cholesterol: 0.06 mmol/L; triglycerides: -0.64 mmol/L; total cholesterol: -0.5 mmol/L) were associated with relatively larger beneficial effects on the lipid profile among all combinations. Compared with metformin + thiazolidinedione, metformin + GLP-1 agonist (mean difference: -0.38; 95% confidence interval [CI]: -0.66 to -0.10) significantly decreased LDL cholesterol. Metformin + thiazolidinedione showed a larger increase than metformin + sulfonylurea in HDL cholesterol (mean difference: 0.1; 95% CI: 0.01 to 0.21).

CONCLUSIONS

The effect of a dual combination of noninsulin anti-hyperglycemic agents on lipids is moderate to small, with metformin + DPP-4 inhibitor and metformin + GLP-1 agonist showing consistent beneficial effects on LDL cholesterol, HDL cholesterol, triglycerides and total cholesterol. Future trials are needed to confirm these findings.

Curcumin improves insulin resistance in skeletal muscle of rats

BACKGROUND AND AIMS

Curcumin has been reported to lower plasma lipids and glucose in diabetic rats, and to decrease body weight in obese rats, which may partly be due to increased fatty acid oxidation and utilization in skeletal muscle.

METHODS AND RESULTS

Diabetic rats induced by high-fat diet plus streptozotocin (STZ, 30 mg/kg BW) were fed a diet containing 50, 150, or 250 mg/kg BW curcumin for 7 wk. Curcumin dose-dependently decreased plasma lipids and glucose and the dose 150 mg/kg BW appeared to be adequate to produce a significant effect. Curcumin supplementation reduced glucose and insulin tolerance measured as areas under the curve. L6 myotubes were treated with palmitate (0.25 mmol/L) in the presence of different levels of curcumin for 24 h in our in vitro experiment. Curcumin at 10 μmol/L was adequate to cause a significant increase in 2-deoxy-[(3)H]d-glucose uptake by L6 myotubes. Curcumin up-regulated expression of phosphorylated AMP-activated protein kinase (AMPK), CD36, and carnitine palmitoyl transferase 1, but down-regulated expression of pyruvate dehydrogenase 4 and phosphorylated glycogen synthase (GS) in both in vivo and in vitro studies. Moreover, curcumin increased phosphorylated acetyl COA carboxylase in L6 myotubes. The effects of curcumin on these enzymes except for GS were suppressed by AMPK inhibitor, Compound C. LKB1, an upstream kinase of AMPK, was activated by curcumin and inhibited by radicicol, an LKB1 destabilizer.

CONCLUSION

Curcumin improves muscular insulin resistance by increasing oxidation of fatty acid and glucose, which is, at least in part, mediated through LKB1-AMPK pathway.

Study comparing the effect of pioglitazone in combination with either metformin or sulphonylureas on lipid profile and glycaemic control in patients with type 2 diabetes (ECLA)

OBJECTIVE

To explore whether the improvement of lipid profile and glycaemic control observed in randomized control trials with pioglitazone (PIO) is replicated under conditions of general clinical practice.

RESEARCH DESIGN AND METHODS

We studied 2388 patients with type 2 diabetes (T2DM) not adequately controlled by monotherapy on either metformin (MET) or sulphonylurea (SU). Addition of a second drug, according to the treating physician's choice, resulted in three groups, PIO + MET, PIO + SU and MET + SU, followed for twelve months, while efficacy and safety parameters were measured at baseline, at six and at twelve months.

RESULTS

A total of 2116 (88.6%) patients completed the study. Diabetic control and lipid profile improved in all three groups, but the improvement was always greater in the two PIO groups. At 12 months PIO + SU and PIO + MET groups compared to SU + MET showed greater increase in HDL cholesterol (8.3% and 9.2 versus 4.3% p < 0.001) and greater decrease in HbA1c (1.53% and 1.46% versus 0.97%, p < 0.001 for both), in triglycerides (20.7% and 21.5% versus 15.2%, p < 0.001) and in LDL cholesterol (15.2% and 14.6% versus 11.3%, p < 0.001 and p < 0.01, respectively). All changes were greater in patients already taking hypolipidaemic drugs. As ECLA was an observational study, the major limitation is the introduction of confounding bias which, however, was accounted for in the statistical analysis.

CONCLUSIONS

Since improvement of both glycaemic control and lipid profile are considered main targets in the management of the diabetic patient, the results of the present study, conducted under conditions of everyday clinical practice, show that pioglitazone may be considered a potential choice for the treatment of type 2 diabetes, when lifestyle and metformin fail.

Treatment of dyslipidemia in patients with type 2 diabetes

Type 2 diabetes is associated with significant cardiovascular morbidity and mortality. Although low-density lipoprotein cholesterol levels may be normal in patients with type 2 diabetes, insulin resistance drives a number of changes in lipid metabolism and lipoprotein composition that render low-density lipoprotein cholesterol and other lipoproteins more pathogenic than species found in patients without type 2 diabetes. Dyslipidemia, which affects almost 50% of patients with type 2 diabetes, is a cardiovascular risk factor characterized by elevated triglyceride levels, low high-density lipoprotein cholesterol levels, and a preponderance of small, dense, low-density lipoprotein particles. Early, aggressive pharmacological management is advocated to reduce low-density lipoprotein cholesterol levels, regardless of baseline levels. A number of lipid-lowering agents, including statins, fibrates, niacin, and bile acid sequestrants, are available to target normalization of the entire lipid profile. Despite use of combination and high-dose lipid-lowering agents, many patients with type 2 diabetes do not achieve lipid targets. This review outlines the characteristics and prevalence of dyslipidemia in patients with type 2 diabetes and discusses strategies that may reduce the risk of cardiovascular disease in this population.

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.

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.