Hyperinsulinemia and sulfonylurea use are independently associated with left ventricular diastolic dysfunction in patients with type 2 diabetes mellitus with suboptimal blood glucose control

Glimepiride Use is Associated with Reduced Cardiovascular Mortality in Patients with Type 2 Diabetes and Chronic Heart Failure: A Prospective Cohort Study

BACKGROUND

Glimepiride has good cardiovascular safety. However, whether glimepiride benefits clinical cardiovascular outcomes is unclear.

METHODS

A total of 21,451 inpatients with type 2 diabetes (T2D) and chronic heart failure (CHF) were analyzed, including 638 who received glimepiride treatment and 20,813 who did not. Propensity score matching yielded 509 pairs (glimepiride and non-glimepiride groups), and both groups were followed up. Kaplan-Meier and Cox regression analyses were used to compare all-cause mortality, cardiovascular mortality, hospitalizations and emergency visits for heart failure, and hospitalizations for acute myocardial infarction or stroke.

RESULTS

During follow-up, the all-cause mortality (adjusted hazard ratio [HR], 0.47; 95% confidence interval [CI], 0.35-0.63; P < 0.001), cardiovascular mortality (adjusted HR, 0.34; 95% CI, 0.24-0.48; P < 0.001), and number of hospitalizations and emergency visits for heart failure (adjusted HR, 0.42; 95% CI, 0.36-0.50; P < 0.001) and hospitalizations for acute myocardial infarction or stroke (adjusted HR, 0.53; 95% CI, 0.38-0.73; P < 0.001) were significantly lower in the glimepiride group; the conclusion remained similar in all subgroups. Furthermore, high-dose glimepiride use (2-4 mg/day) was associated with lower cardiovascular mortality than low-dose (1 mg/day) (adjusted HR, 0.55; 95% CI, 0.31-0.99; P = 0.047). Glimepiride exhibited good molecular docking with soluble epoxide hydrolase (sEH) and increased the level epoxyeicosatrienoic acid (EET).

CONCLUSIONS

Long-term continuous glimepiride use is associated with better survival, fewer hospitalizations and emergency visits for heart failure, and fewer hospitalizations for acute myocardial infarction or stroke in patients with T2D and CHF. High-dose glimepiride has greater cardiovascular protective advantages than low-dose glimepiride. The cardiovascular protective effect of glimepiride may be related to the EET level increase through sEH inhibition.

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.

Left ventricular diastolic dysfunction in diabetes mellitus and the therapeutic role of exercise training

Abstract Left ventricular diastolic dysfunction (LVDD) with normal ejection fraction is considered common among people with diabetes mellitus (DM). LVDD is a progressive condition and an independent predictor of mortality in diabetic patients. The etiopathogenesis of LVDD is multifactorial, including diabetes associated comorbidities, such as hypertension, coronary atherosclerosis and obesity, as well as myocardial vascular and metabolic disturbances which lead to diabetic cardiomyopathy. Early stages of LVDD may be detected using echocardiographic techniques. Treatment strategies evolve, based on a better understanding of pathogenic mechanisms, although it is still difficult to efficiently control LVDD evolution. This review synthesizes the main pathophysiological processes and clinical features that characterize DM associated LVDD. Among treatment options, the therapeutic relevance of exercise training programs is underlined. Key words: diabetes mellitus, left ventricular diastolic dysfunction, physical training,

The impact of oral anti-diabetic medications on heart failure: lessons learned from preclinical studies

The prevalence of heart failure (HF) in the diabetic population has rapidly increased over the past 2 decades, triggering research about the impact of oral anti-diabetic medications on it. Unfortunately, not all success at the bench in preclinical experiments has translated to success at the bedside. On the other hand, recent promising clinical data from oral SGLT2 inhibitors mainly lack mechanistic explanation from experimental studies. Hence, it is critical to understand the lessons learned from prior translational studies to gain a better knowledge of the mechanisms of oral anti-diabetic drugs in HF. This review aims to summarize the results from preclinical studies regarding the interaction between oral anti-diabetic medications and heart failure development and/or exacerbation. Although there is a wide spectrum of controversial results, the underlying hope is that the clinical success rate will improve and the adverse events during ineffective targeted therapy will be limited.

Effect of canagliflozin on left ventricular diastolic function in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) greatly increases the risks of cardiovascular disease and heart failure. In particular, left ventricular diastolic dysfunction that develops from the early stages of T2DM is an important factor in the onset and exacerbation of heart failure. The effect of sodium-glucose cotransporter 2 inhibitors on left ventricular diastolic function has not been elucidated. We have performed the first prospective study on the effects of canagliflozin on left ventricular diastolic function in T2DM.

METHODS

This study was performed to evaluate the effects of additional treatment with canagliflozin for 3 months on left ventricular diastolic function in patients with T2DM. A total of 38 patients with T2DM were consecutively recruited for this study. Left ventricular diastolic function was assessed by echocardiography. The primary study outcome was a change in the septal E/e' as a parameter of left ventricular diastolic function.

RESULTS

A total of 37 patients (25 males and 12 females) were included in the analysis. Mean age of participants was 64.2 ± 8.1 years (mean ± SD), mean duration of diabetes was 13.5 ± 8.1 years, and mean HbA1c was 7.9 ± 0.7%. Of the participants, 86.5% had hypertension, 100% had dyslipidemia, and 32.4% had cardiovascular disease. Canagliflozin significantly improved left ventricular diastolic function (septal E/e' ratio 13.7 ± 3.5-12.1 ± 2.8, p = 0.001). Furthermore, among the various parameters that changed through the administration of canagliflozin, only changes in hemoglobin significantly correlated with changes in the septal E/e' ratio (p = 0.002). In multiple regression analysis, changes in hemoglobin were also revealed to be an independent predictive factor for changes in the septal E/e' ratio.

CONCLUSIONS

This study showed for the first time that canagliflozin could improve left ventricular diastolic function within 3 months in patients with T2DM. The benefit was especially apparent in patients with substantially improved hemoglobin values. Trial registration UMIN Clinical Trials Registry UMIN000028141.

Serum Bilirubin Concentration is Associated with Left Ventricular Remodeling in Patients with Type 2 Diabetes Mellitus: A Cohort Study

INTRODUCTION

Previous studies have shown that serum bilirubin concentration is inversely associated with the risk of cardiovascular disease. The relationship between serum bilirubin concentration and left ventricular geometry, however, has not been investigated in patients with diabetes mellitus.

METHODS

In this cohort study, 158 asymptomatic patients with type 2 diabetes mellitus without overt heart disease were enrolled. Left ventricular structure and function were assessed using echocardiography. Serum bilirubin concentration, glycemic control, lipid profile, and other clinical characteristics were evaluated, and their association with left ventricular geometry was determined. Patients with New York Heart Association Functional Classification greater than I, left ventricular ejection fraction less than 50%, history of coronary artery disease, severe valvulopathy, chronic atrial fibrillation, or creatinine clearance less than 30 ml/min, and those receiving insulin treatment, were excluded.

RESULTS

Univariate analyses showed that relative wall thickness (RWT) was significantly correlated with diastolic blood pressure (P = 0.003), HbA1c (P = 0.024), total cholesterol (P = 0.043), urinary albumin (P = 0.023), and serum bilirubin concentration (P = 0.009). There was no association between left ventricular mass index and serum bilirubin concentration. Multivariate linear regression analysis showed that log RWT was positively correlated with diastolic blood pressure (P = 0.010) and that log RWT was inversely correlated with log bilirubin (P = 0.003). In addition, the patients with bilirubin less than 0.8 mg/dl had a higher prevalence of concentric left ventricular remodeling compared with those with bilirubin 0.8 mg/dl or more.

CONCLUSION

Our study shows that the serum bilirubin concentration may be associated with the progression of concentric left ventricular remodeling in patients with type 2 diabetes mellitus.

Insulin and β Adrenergic Receptor Signaling: Crosstalk in Heart

Recent advances show that insulin may affect β adrenergic receptor (βAR) signaling in the heart to modulate cardiac function in clinically relevant states, such as diabetes mellitus (DM) and heart failure (HF). Conversely, activation of βAR regulates cardiac glucose uptake and promotes insulin resistance (IR) in HF. Here, we discuss the recent characterization of the interaction between the cardiac insulin receptor (InsR) and βAR in the myocardium, in which insulin stimulation crosstalks with cardiac βAR via InsR substrate (IRS)-dependent and G-protein receptor kinase 2 (GRK2)-mediated phosphorylation of β₂AR. The insulin-induced phosphorylation promotes β₂AR coupling to G_i and expression of phosphodiesterase 4D, which both inhibit cardiac adrenergic signaling and compromise cardiac contractile function. These recent developments could support new approaches for the effective prevention or treatment of obesity- or DM-related HF.

The relationship between insulin sensitivity and heart rate-corrected QT interval in patients with type 2 diabetes

BACKGROUND

Reduced insulin sensitivity not only contributes to the pathogenesis of type 2 diabetes but is also linked to multiple metabolic risk factors and cardiovascular diseases (CVD). A prolonged heart rate-corrected QT interval (QTc interval) is related to ventricular arrhythmias and CVD mortality and exhibits a high prevalence among type 2 diabetes patients. The aim of the study was to investigate the relationship between insulin sensitivity and the QTc interval in patients with type 2 diabetes.

METHODS

This cross-sectional observational study recruited 2927 patients with type 2 diabetes who visited the Affiliated Haian Hospital and Second Affiliated Hospital of Nantong University. The insulin sensitivity index (Matsuda index, ISI_Matsuda) derived from 75-g OGTT and other metabolic risk factors were examined in all patients. The QTc interval was estimated using a resting 12-lead electrocardiogram, and an interval longer than 440 ms was considered abnormally prolonged.

RESULTS

The QTc interval was significantly and negatively correlated with the ISI_Matsuda (r = -0.296, p < 0.001), and when the multiple linear regression analysis was adjusted for anthropometric parameters, metabolic risk factors, and current antidiabetic treatments, the QTc interval remained significantly correlated with the ISI_Matsuda (β = -0.23, t = -12.63, p < 0.001). The proportion of patients with prolonged QTc interval significantly increased from 12.1% to 17.9%, 25.6% and 37.9% from the fourth to third, second and first quartile of the ISI_Matsuda, respectively. After adjusting for anthropometric parameters by multiple logistic regression analysis, the corresponding odd ratios (ORs) for prolonged QTc interval of the first, second and third quartiles versus the fourth quartile of ISI_Matsuda were 3.11 (95% CI 2.23-4.34), 2.09 (1.51-2.88) and 1.53 (1.09-2.14), respectively, and p for trend was <0.001.

CONCLUSIONS

Reduced insulin sensitivity is associated with an increase in the QTc interval in patients with type 2 diabetes.