The effects of dual-therapy intensification with insulin or dipeptidylpeptidase-4 inhibitor on cardiovascular events and all-cause mortality in patients with type 2 diabetes: A retrospective cohort study

Effects of continuous use of metformin on cardiovascular outcomes in patients with type 2 diabetes after acute myocardial infarction: A protocol for systematic review and meta-analysis

BACKGROUND

To our knowledge, no meta-analyses or reviews have investigated the efficacy and safety of metformin on cardiovascular outcomes after acute myocardial infarction (AMI) in patients with type 2 diabetes mellitus (T2DM). We thus conduct a high-quality systematic review and meta-analysis to assess the efficacy and safety of metformin on cardiovascular outcomes after AMI in patients with T2DM.

METHODS

In this systematic review and meta-analysis, we will search PUBMED, Scopus, EMBASE, and Cochrane Library databases through April, 2021. The study is structured to adhere to PRISMA guidelines (i.e., Preferred Reporting Items for Systematic Reviews and Meta-analyses). The literature search, data extraction, and quality assessments are conducted independently by 2 authors. Outcome measures include all-cause mortality; complications such as acute kidney injury, lactic acidosis, hospitalization for AMI or stroke, or death. Where disagreement in the collection of data occurs, this is resolved through discussion. Review Manager Software (v 5.3; Cochrane Collaboration) is used for the meta-analysis. Two independent reviewers will assess the risk of bias of the included studies at study level.

RESULTS

It is hypothesized that metformin use at the post-AMI is associated with decreased risk of cardiovascular disease and death in patients with T2DM.

CONCLUSIONS

This study expects to provide credible and scientific evidence for the efficacy and safety of metformin on cardiovascular outcomes after AMI in patients with T2DM.

REGISTRATION NUMBER

10.17605/OSF.IO/S3MBP.

Insulin: too much of a good thing is bad

BACKGROUND

Insulin shares a limited physiological concentration range with other endocrine hormones. Not only too low, but also too high systemic insulin levels are detrimental for body functions.

MAIN BODY

The physiological function and clinical relevance of insulin are usually seen in association with its role in maintaining glucose homeostasis. However, insulin is an anabolic hormone which stimulates a large number of cellular responses. Not only too low, but also excess insulin concentrations are detrimental to the physiological balance. Although the glucoregulatory activity of insulin is mitigated during hyperinsulinemia by dampening the efficiency of insulin signaling ("insulin resistance"), this is not the case for most other hormonal actions of insulin, including the promotion of protein synthesis, de novo lipogenesis, and cell proliferation; the inhibition of lipolysis, of autophagy-dependent cellular turnover, and of nuclear factor E2-related factor-2 (Nrf2)-dependent antioxidative; and other defense mechanisms. Hence, there is no general insulin resistance but selective impairment of insulin signaling which causes less glucose uptake from the blood and reduced activation of endothelial NO synthase (eNOS). Because of the largely unrestricted insulin signaling, hyperinsulinemia increases the risk of obesity, type 2 diabetes, and cardiovascular disease and decreases health span and life expectancy. In epidemiological studies, high-dose insulin therapy is associated with an increased risk of cardiovascular disease. Randomized controlled trials of insulin treatment did not observe any effect on disease risk, but these trials only studied low insulin doses up to 40 IU/day. Proof for a causal link between elevated insulin levels and cardiovascular disease risk comes from Mendelian randomization studies comparing individuals with genetically controlled low or high insulin production.

CONCLUSIONS

The detrimental actions of prolonged high insulin concentrations, seen also in cell culture, argue in favor of a lifestyle that limits circadian insulin levels. The health risks associated with hyperinsulinemia may have implications for treatment regimens used in type 2 diabetes.

Reporting and variability of constructing medication treatment episodes in pharmacoepidemiology studies: A methodologic systematic review using the case study of DPP-4 inhibitors and cardiovascular outcomes

PURPOSE

In pharmacoepidemiologic studies, estimating medication adherence, persistence, and exposure patterns is critical. Constructing medication treatment episodes from prescription claims data involves assumptions related to grace period, carry-over, and lag effect, but there are no guidelines for these assumptions. We evaluated reporting and variability of these parameters in pharmacoepidemiology studies, using a case study of antihyperglycemic medications and major adverse cardiovascular events (MACE).

METHODS

We conducted a systemic review using MEDLINE and EMBASE for studies published prior to January 2, 2020 comparing the risk of MACE between dipeptidyl peptidase 4 (DPP-4) inhibitors and active comparators. We extracted study characteristics and results, including grace period, carry-over, and lag effect. Risk of bias was assessed by the Newcastle-Ottawa scale, and assessments for prevalent user, immortal time, time lag, and time window biases.

RESULTS

A total of 14/1850 studies identified were included. Grace period was not reported in 5 (35.7%) studies and ranged from 0 days to 180 days when reported. Carry-over was not reported in 10 studies (71.4%). Lag effect was not reported in nine (71.4%) studies and ranged from 0 days to 180 days when reported. No studies conducted sensitivity analyses examining the effects of these assumptions on study findings. Predominant biases were inadequate follow-up time, comparability of cohorts, prevalent use, and lag time bias.

CONCLUSIONS

Use of grace period, carry-over, and lag effect were poorly reported and highly variable. Future pharmacoepidemiology studies should improve reporting, justify ranges for these parameters, and conduct sensitivity analyses to evaluate effects of these assumptions.

Clinical outcomes of basal insulin and oral antidiabetic agents as an add-on to dual therapy in patients with type 2 diabetes mellitus

While basal insulin remains the most effective antidiabetic agent and substantially reduces the risk of hypoglycemia, few studies have examined the comparative effect of basal insulin in the real-world setting. This study aimed to assess the outcomes of adding basal insulin compared with thiazolidinediones (TZDs) or dipeptidyl peptidase-4 inhibitors (DPP-4is) as a third antidiabetic agent in patients with type 2 diabetes mellitus (T2DM). A retrospective cohort study involving T2DM was conducted with health administrative data in Taiwan. Patients starting a third antidiabetic agent after receiving a metformin-containing dual combination were identified. The study endpoints included composite major adverse cardiovascular events (MACEs), all-cause mortality, and hypoglycemia. Propensity score matching and Cox modeling were used for analysis. After matching, the basal insulin and TZD groups contained 6,101 and 11,823 patients, respectively, and the basal insulin and DPP-4i groups contained 6,051 and 11,900 patients, respectively. TZDs and DPP-4is were both associated with similar risks of MACEs and hypoglycemia but a lower risk of all-cause mortality than basal insulin (TZDs: HR 0.55, 95% CI 0.38-0.81; DPP-4is: HR 0.56, 95% CI 0.39-0.82). Further studies are needed to elucidate the findings of increased all-cause mortality risk in patients receiving basal insulin, especially those with advanced diabetes.

Intensification with dipeptidyl peptidase-4 inhibitor, insulin, or thiazolidinediones and risks of all-cause mortality, cardiovascular diseases, and severe hypoglycemia in patients on metformin-sulfonylurea dual therapy: A retrospective cohort study

BACKGROUND

Although patients with type 2 diabetes mellitus (T2DM) may fail to achieve adequate hemoglobin A1c (HbA1c) control despite metformin-sulfonylurea (Met-SU) dual therapy, a third-line glucose-lowering medication-including dipeptidyl peptidase-4 inhibitor (DPP4i), insulin, or thiazolidinedione (TZD)-can be added to achieve this. However, treatment effects of intensification with the medications on the risk of severe hypoglycemia (SH), cardiovascular disease (CVD), and all-cause mortality are uncertain. Study aim was to compare the risks of all-cause mortality, CVD, and SH among patients with T2DM on Met-SU dual therapy intensified with DPP4i, insulin, or TZD.

METHODS AND FINDINGS

We analyzed a retrospective cohort data of 17,293 patients with T2DM who were free from CVD and on Met-SU dual therapy and who were intensified with DPP4i (n = 8,248), insulin (n = 6,395), or TZD (n = 2,650) from 2006 to 2017. Propensity-score weighting was used to balance out baseline covariates across groups. Hazard ratios (HRs) for all-cause mortality, CVD, and SH were assessed using Cox proportional hazard models. Mean age of all patients was 58.56 ± 11.41 years. All baseline covariates achieved a balance across the 3 groups. Over a mean follow-up period of 34 months with 49,299 person-years, cumulative incidences of all-cause mortality, SH, and CVD were 0.061, 0.119, and 0.074, respectively. Patients intensified with insulin had higher risk of all-cause mortality (HR = 2.648, 95% confidence interval [CI] 2.367-2.963, p < 0.001; 2.352, 95% CI 2.123-2.605, p < 0.001) than those intensified with TZD and DPP4i, respectively. Insulin users had the greatest risk of SH (HR = 1.198, 95% CI 1.071-1.340, p = 0.002; 1.496, 95% CI 1.342-1.668, p < 0.001) compared with TZD and DPP4i users, respectively. Comparing between TZDs and DPP4i, TZDs were associated with a higher risk of SH (HR = 1.249, 95% CI 1.099-1.419, p < 0.001) but not all-cause mortality (HR = 0.888, 95% CI 0.776-1.016, p = 0.084) or CVD (HR = 1.005, 95% CI 0.915-1.104, p = 0.925). Limitations of this study included the lack of data regarding lifestyle, drug adherence, time-varying factors, patients' motivation, and cost considerations. A limited duration of patients intensifying with TZD might also weaken the strength of study results.

CONCLUSIONS

Our results indicated that, for patients with T2DM who are on Met-SU dual therapy, the addition of DPP4i was a preferred third-line medication among 3 options, with the lowest risks of mortality and SH and posing no increased risk for CVD events when compared to insulin and TZD. Intensification with insulin had the greatest risk of mortality and SH events.

Effects on clinical outcomes of intensifying triple oral antidiabetic drug (OAD) therapy by initiating insulin versus enhancing OAD therapy in patients with type 2 diabetes: A nationwide population-based, propensity-score-matched cohort study

AIMS

To compare the effects of initiating insulin as a fourth-line antidiabetic therapy with the effects of enhancing oral antidiabetic drug (OAD) therapy in patients with type 2 diabetes mellitus (T2DM) with triple OAD therapy failure.

MATERIALS AND METHODS

We conducted a nationwide population-based, retrospective cohort study involving 1022 (without prevalent diabetes-related complications [PDRCs]) and 2077 (with/without PDRCs) propensity score-matched pairs of fourth-line insulin therapy users and enhanced OAD therapy users identified in the period 2004 to 2010. Clinical outcomes including a composite cardiovascular outcome (myocardial infarction, stroke, heart failure or ischaemic heart disease), peripheral vascular disease (PVD), hypoglycaemia and all-cause mortality were assessed up to 2013. Hypoglycaemia was adjusted in Cox models to consider its potential effect on study outcomes.

RESULTS

In a T2DM cohort without PDRCs, fourth-line insulin therapy was not associated with greater risks of clinical outcomes, except hypoglycaemia (hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.02-2.07), compared with enhanced OAD therapy. Among patients with T2DM with/without PDRCs, fourth-line insulin therapy was associated with greater risks of the composite cardiovascular outcome (HR 1.23, 95% CI 1.03-1.46), heart failure (HR 1.59, 95% CI 1.12-2.25), ischaemic heart disease (HR 1.37, 95% CI 1.09-1.73), PVD (HR 1.17, 95% CI 1.00-1.36), hypoglycaemia (HR 1.49, 95% CI 1.20-1.85) and all-cause mortality (HR 1.48, 95% CI 1.01-2.17), but adjustment for hypoglycaemia significantly attenuated the risk of heart failure (HR 1.34, 95% CI 0.92-1.94), PVD (HR 1.15, 95% CI 0.98-1.34) and all-cause mortality (HR 1.30, 95% CI 0.84-1.99).

CONCLUSIONS

Initiation of fourth-line insulin therapy can be considered for patients with T2DM with triple OAD therapy failure, and the importance of awareness and prevention of hypoglycaemia among insulin-treated patients with T2DM cannot be overstated.

Editor’s Choice- Impact of insulin-treated diabetes on cardiovascular outcomes following high-risk myocardial infarction

Background:

Diabetes is associated with poor cardiovascular outcomes, and insulin-treated patients usually have a worse prognosis than non-insulin-treated subjects. The relationship between insulin treatment and outcomes in high-risk myocardial infarction patients has not been described in a large dataset.

Methods:

To investigate the association between insulin-treated diabetes and long-term cardiovascular outcomes in patients with high-risk myocardial infarction, we used adjusted Cox models to compare cardiovascular mortality and hospitalisation among 28,771 patients grouped by diabetes status and insulin treatment from four randomised clinical trials (VALIANT, EPHESUS, OPTIMAAL, CAPRICORN) of acute myocardial infarction complicated by heart failure and/or left ventricular systolic dysfunction.

Results:

After an approximately 2-year follow-up, patients with no diabetes (21,386 subjects, 74.3%), non-insulin-treated diabetes (4977 patients, 17.3%) and insulin-treated diabetes (2409 subjects, 8.4%) had an incremental yearly mortality risk (15.8%, 21.3% and 28.1%, respectively). Insulin-treated diabetes patients presented with a higher cardiovascular burden and comorbidities. After adjustment for 18 baseline covariates, patients with non-insulin-treated and insulin-treated diabetes were at higher risk of cardiovascular death (hazard ratio (HR) 1.25, 95% confidence interval (CI) 1.13–1.38 and HR 1.49, 95% CI 1.31–1.69, respectively; P for comparison of non-insulin-treated vs. insulin-treated diabetes =0.016) and cardiovascular hospitalisation (HR 1.33, 95% CI 1.25–1.41 and HR 1.16, 95% CI 1.11–1.22, respectively) compared to patients without diabetes. These results remained consistent after further adjustment for medications and left ventricular ejection fraction.

Conclusions:

Insulin-treated diabetes patients had higher event rates than diabetes patients taking oral treatments and patients without diabetes. However, insulin-treated diabetes patients had more comorbidities and atherosclerotic disease, precluding any causality suggestion between insulin treatment and outcomes. This high-risk population may require specific and/or more intense cardiovascular protective therapies.

Are the favorable cardiovascular outcomes of empagliflozin treatment explained by its effects on multiple cardiometabolic risk factors? A simulation of the results of the EMPA-REG OUTCOME trial

AIMS

It is unclear whether the favorable impact of empagliflozin on cardiovascular outcomes (CVOs) is due to its effect on multiple cardiometabolic risk factors (CRFs).

METHODS

We used the Michigan Model for Diabetes, a validated computer simulation model, and published data from the EMPA-REG OUTCOME trial to estimate three-year CVOs in the placebo and pooled empagliflozin treatment groups to assess whether the observed benefits might be attributable to differences in CRFs.

RESULTS

When we programmed the model to match the baseline characteristics of the trial population and the reported trajectories of five CRFs (weight, HbA1c, systolic blood pressure, low- and high-density lipoprotein cholesterol), the simulated hazard ratio (HR) for the primary composite CVO did not differ from the reported result. The simulated HRs for fatal/nonfatal myocardial infarction and coronary revascularization procedure fell within the reported 95% confidence intervals (CIs), but those for fatal/nonfatal stroke, hospitalization for heart failure, cardiovascular death, and all-cause mortality fell outside the reported 95% CIs. The effects of empagliflozin on CRFs accounted for approximately half of the observed benefit for the primary composite CVO, but explained smaller proportions of risk reductions for hospitalization for heart failure, cardiovascular death, and all-cause mortality.

CONCLUSIONS

The effects of empagliflozin on multiple CRFs account for some but not all of reduced risks of CVOs in the EMPA-REG OUTCOME trial. More comparable control of established CRFs in type 2 diabetes CVO trials of antidiabetic agents with pleiotrophic effects would facilitate the interpretation of the observed outcomes.

The effect of antidiabetic medications on non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and is prevalent in more than 50% of patients with type II diabetes. At present, there is no approved therapy for NASH. Until now, the only proven effective interventions in improving biochemical and histological features of NASH, including fibrosis, are weight loss and physical activity even without weight loss. Because of the common epidemiological and pathophysiological features between NAFLD and T2DM, many antidiabetics drugs have been tested in patients with NAFLD over the years. Among these, pioglitazone and liraglutide seem to improve some histological features of NASH but have no clear effect on fibrosis. Metformin has been largely studied in the past years without convincing evidence of improving NAFLD. Data on other compounds such as DDP-4 and SGLT-2 inhibitors are limited. The rational and results of such studies are discussed in the present review.

Coadministration of DPP-4 inhibitor and insulin therapy does not further reduce the risk of cardiovascular events compared with DPP-4 inhibitor therapy in diabetic foot patients: a nationwide population-based study

BACKGROUND

The effect of combined insulin and dipeptidyl peptidase-4 inhibitor (DPP4i) therapy on major adverse cardiovascular events (MACEs) in patients with diabetic foot is unclear.

METHODS

We conducted this nationwide cohort study using longitudinal claims data obtained from the Taiwan National Health Insurance program and included 19,791 patients with diabetic foot from 2007 to 2014. Patients receiving DPP4i-based therapy and/or insulin-based therapy after a diagnosis of diabetic foot were categorized into combined, DPP4i- or insulin-based groups, respectively. The risk of MACEs including nonfatal myocardial infarction, nonfatal stroke, cardiac death, and heart failure was assessed using Cox proportional hazards analysis and propensity score matching.

RESULTS

Among the 19,791 patients with diabetic foot (mean age, 58.8 years [SD, 12.5]; men, 51.2%), 6466 received DPP4i-based therapy, 1925 received insulin-based therapy, and 11,400 received combined DPP4i and insulin therapy. The DPP4i-based and insulin-based groups had a lower risk of MACEs (HR 0.53, 95% CI 0.50-0.57 DPP4i only; HR 0.89, 95% CI 0.81-0.97 insulin only) than the combined group. After propensity score matching, the incidence of all complications in the DPP4i-based group was still significantly lower than that in the combined group (HR 0.55, 95% CI 0.51-0.59 for MACEs; HR 0.32, 95% CI 0.24-0.42 for nonfatal myocardial infarction; HR 0.70, 95% CI 0.63-0.78 for nonfatal stroke; HR 0.22, 95% CI 0.13-0.38 for cardiac death; HR 0.22, 95% CI 0.19-0.25 for any death; HR 0.16, 95% CI 0.13-0.20 for amputation). In the diabetic foot patients with end-stage renal disease (ESRD), the benefit of a lower incidence of MACEs in the DPP4i-based group disappeared (HR 0.77, 95% CI 0.58-1.08).

CONCLUSIONS

This study demonstrated that the patients with diabetic foot receiving DPP4i-based therapy had a lower risk of MACEs than those receiving combined therapy with DPP4i and insulin, but that the effect disappeared in those with concurrent ESRD.

Insulin Therapy Increases Cardiovascular Risk in Type 2 Diabetes

Insulin therapy increased cardiovascular (CV) risk and mortality among type 2 diabetes (T2D) patients in several recently reported clinical outcomes trials. To assess whether this association is causative or coincidental, PubMed searches were used to query the effects of insulin therapy for T2D on CV health and longevity from large-scale outcomes trials, meta-analyses, and patient registry studies, as well as basic research on insulin's direct and pleiotropic actions. Although several old studies provided conflicting results, the majority of large observational studies show strong dose-dependent associations for injected insulin with increased CV risk and worsened mortality. Insulin clearly causes weight gain, recurrent hypoglycemia, and, other potential adverse effects, including iatrogenic hyperinsulinemia. This over-insulinization with use of injected insulin predisposes to inflammation, atherosclerosis, hypertension, dyslipidemia, heart failure (HF), and arrhythmias. These associations support the findings of large-scale evaluations that strongly suggest that insulin therapy has a poorer short- and long-term safety profile than that found to many other anti-T2D therapies. The potential adverse effects of insulin therapy should be weighed against proven CV benefits noted for select other therapies for T2D as reported in recent large randomized controlled trials.