Glycemic control and cardiovascular mortality

Evolving understanding of cardiovascular protection by SGLT2 inhibitors: focus on renal protection, myocardial effects, uric acid, and magnesium balance

Robust clinical data indicate that inhibitors of the sodium/glucose cotransporter 2 (SGLT2) dramatically improve clinical outcomes in diabetes, especially heart failure and progression of kidney disease. Factors that may contribute to these findings include: 1) improved glycemic control, 2) diuresis and reduced extracellular fluid volume, 3) reduced serum uric acid levels, 3) direct myocardial effects, 4) reduction in proteinuria and preservation of kidney function, and 5) correction of diabetic magnesium deficiency. Understanding the mechanisms by which SGLT2 inhibitors improve cardiovascular outcomes has the potential to improve clinical management not only of diabetes, but also of other cardiovascular disorders such as heart failure and chronic kidney disease.

Vanillic acid alleviates palmitic acid-induced oxidative stress in human umbilical vein endothelial cells via Adenosine Monophosphate-Activated Protein Kinase signaling pathway

Vanillic acid (VA), one of the phenolic acids metabolized by anthocyanidins, can modulate vascular reactivity by reducing the superoxide. We investigated that VA alleviated fatty acid-induced oxidative stress and clarified its potential mechanisms in human umbilical vein endothelial cells (HUVECs). Our results showed that VA reduced the production of reactive oxygen species and malondialdehyde levels. It also restored mitochondrial membrane potential and enhanced the activities of antioxidant enzymes. In addition, VA promoted the expression of p-Nrf2 and HO-1 through LKB1/AMPK signaling pathway, as well as the level of SIRT1 and PGC-1α. Moreover, compound C reduced the effect of VA on the enhancement of p-Nrf2 and HO-1. These results indicated that AMPK was an important target molecule of VA in the process of alleviating oxidative stress in HUVECs, providing a new potential evidence for vascular protection of anthocyanin in vitro. PRACTICAL APPLICATIONS: As a phenolic derivative and phase II metabolite of anthocyanins in vivo, VA can be found in various edible plants and fruits. This study revealed that VA improved oxidative stress in endothelial cells stimulated by palmitic acid by activating AMPK and its downstream proteins. VA could be a potential functional material for the protection of diabetic vascular complications.

Functional differences between healthy and diabetic endothelial cells on topographical cues

The endothelial lining of blood vessels is severely affected in type II diabetes. Yet, there is still a paucity on the use of diabetic endothelial cells for study and assessment of implantable devices targeting vascular disease. This critically impairs our ability to determine appropriate topographical cues to be included in implantable devices that can be used to maintain or improve endothelial cell function in vivo. Here, the functional responses of healthy and diabetic human coronary arterial endothelial cells were studied and observed to differ depending on topography. Gratings (2 μm) maintained normal endothelial functions such as adhesiveness, angiogenic capacity and cell-cell junction formation, and reduced immunogenicity of healthy cells. However, a significant and consistent effect was not observed in diabetic cells. Instead, diabetic endothelial cells cultured on the perpendicularly aligned multi-scale hierarchical gratings (250 nm gratings on 2 μm gratings) drastically reduced the uptake of oxidized low-density lipoprotein, decreased immune activation, and accelerated cell migration. Concave microlens (1.8 μm diameter) topography was additionally observed to overwhelmingly deteriorate diabetic endothelial cell function. The results of this study support a new paradigm and approach in the design and testing of implantable devices and biomedical interventions for diabetic patients.

GATA4 protects against hyperglycemia‑induced endothelial dysfunction by regulating NOX4 transcription

Endothelial dysfunction is one of the most common complications associated with diabetes and may lead to atherosclerosis. Conflicting reports indicate that NADPH oxidase 4 (NOX4) induces hydrogen peroxide production and cytotoxicity, but also has a protective effect on endothelial dysfunction. The present study aimed to identify the transcription factor responsible for NOX4 expression using a transcription factor activation profiling plate array and chromatin immunoprecipitation. Data from these analyses indicated that GATA-binding protein 4 (GATA4) was able to mediate NOX4 transcription and is downregulated in human umbilical vein endothelial cells (HUVECs) that were exposed to hyperglycemic conditions as well as in the endothelial cells of a mouse diabetes model. Overexpression of GATA4 was demonstrated to lead to increased expression of NOX4 mRNA and protein. Furthermore, GATA4 overexpression resulted in increased nitric oxide (NO) production through the upregulation of endothelial NO synthase phosphorylation. Treatment with simvastatin, a drug known to preserve endothelial function through an unknown mechanism, improved endothelial cell function by upregulating GATA4 expression in HUVECs exposed to hyperglycemia. Results from these experiments demonstrated that GATA4 may inhibit diabetes-induced endothelial dysfunction by acting as a transcription factor for NOX4 expression and increasing NO production. Thus, the present study revealed a novel molecular mechanism underlying endothelial dysfunction in diabetes and identified GATA4 as a potential therapeutic target.

Long-term follow-up of a hospital-based, multi-intervention programme in type 2 diabetes mellitus: impact on cardiovascular events and death

Objective

To report the long-term impact on cardiovascular (CV) outcomes and mortality of a 2-year hospital-based multi-interventional care programme as compared with general practitioner (GP)-provided standard care.

Methods

Patients with type 2 diabetes with ≥ 1 additional CV risk factor were randomized to 2 years of specialist-based, multi-intervention comprising lifestyle modification and specific pharmacological treatment, or GP-based standard care. After the 2-year intervention period, all participants returned to pre-study care, but were followed up for CV outcomes and mortality. The primary outcome was time to any first severe CV event or death.

Results

A total of 120 patients (31 women) were enrolled in the study. During the mean ± SD observational period of 8.7 ± 2.0 years, 27 patients (16 and 11 in the multi-intervention and standard care groups, respectively) experienced at least one primary outcome event, with a hazard ratio (HR) if allocated to the multi-intervention group of 1.73 (95% confidence interval (CI) 0.80, 3.75). The HR for total mortality was 1.82 (95% CI 0.66, 5.01).

Conclusions

Hospital-based multi-intervention in patients with type 2 diabetes mellitus improved long-term glycaemic control, but failed to reduce CV outcomes and deaths.

Clinical trials.gov id: NCT00133718.

Diabetes, Endothelial Dysfunction, and Vascular Repair: What Should a Diabetologist Keep His Eye on?

Cardiovascular complications are the most common complications of diabetes mellitus. A prominent attribute of diabetic cardiovascular complications is accelerated atherosclerosis, considered as a still incurable disease, at least at more advanced stages. The discovery of endothelial progenitor cells (EPCs), able to replace old and injured mature endothelial cells and capable of differentiating into healthy and functional endothelial cells, has offered the prospect of merging the traditional theories on the pathogenesis of atherosclerosis with evolving concepts of vascular biology. The literature supports the notion that EPC alterations are involved in the pathogenesis of vascular diseases in diabetics, but at present many questions remain unanswered. In this review the aspects linking endothelial progenitor cells to the altered vascular biology in diabetes mellitus are discussed.

Neutral impact on systolic and diastolic cardiac function of 2 years of intensified multi-intervention in type 2 diabetes: the randomized controlled Asker and Bærum Cardiovascular Diabetes (ABCD) study

BACKGROUND

Patients with type 2 diabetes (T2D) are prone to develop preclinical myocardial dysfunction, but no single strategy to prevent progression to heart failure has been established. We aimed to assess whether intensified global cardiovascular (CV) risk factor control would improve left ventricular (LV) systolic and diastolic function as compared with standard of care.

METHODS

A total of 100 patients with ≥1 CV risk factor (29% female, mean ± SD age 58 ± 10 years, LV ejection fraction 63 ± 8%, 16% with LV diastolic dysfunction) were randomized to 2 years of intensified CV risk multi-intervention (INT, n = 50) or standard care (STAND, n = 50). Echocardiography, including tissue Doppler imaging, and maximum exercise test were performed at baseline and study end. Multi-intervention comprised lifestyle intervention and pharmacologic treatment to reach strict prespecified CV risk factor goals, whereas STAND group received current guideline care.

RESULTS

Greater reductions were observed for hemoglobin A1c and total cholesterol in the INT group (P < .001 and P = .021, respectively), whereas blood pressure reduction was similar. Work capacity increased in INT and decreased in STAND (P = .014). There was no significant between-group difference in the change in any of the echocardiographic parameters.

CONCLUSIONS

Two years of intensified multi-intervention in patients with T2D improved work capacity and glycemic and lipid control and had no significant benefit or harm on resting cardiac function.

The association of body mass index with the risk of type 2 diabetes: a case-control study nested in an electronic health records system in the United States

OBJECTIVES

Obesity is a known risk factor for type 2 diabetes (T2D). We conducted a case-control study to assess the association between body mass index (BMI) and the risk of being diagnosed with T2D in the United States.

METHODS

We selected adults (≥ 18 years old) who were diagnosed with T2D (defined by ICD-9-CM diagnosis codes or use of anti-diabetic medications) between January 2004 and October 2011 ("cases") from an electronic health records database provided by an integrated health system in the Middle Atlantic region. Twice as many individuals enrolled in the health system without a T2D diagnosis during the study period ("controls") were selected based on age, sex, history of cardiac comorbidities or hyperinflammatory state (defined by C-reactive protein and erythrocyte sedimentation rate), and use of psychiatric or beta blocker medications. BMI was measured during one year prior to the first observed T2D diagnosis (for cases) or a randomly assigned date (for controls); individuals with no BMI measure or BMI < 18.5 kg/m2 were excluded. We assessed the impact of increased BMI (overweight: 25-29.9 kg/m2; Obesity Class I: 30-34.9 kg/m2; Obesity Class II: 35-39.9 kg/m2; Obesity Class III: ≥40 kg/m2), relative to normal BMI (18.5-24.9 kg/m2), on a T2D diagnosis using odds ratios (OR) and relative risks (RR) estimated from multiple logistic regression results.

RESULTS

We included 12,179 cases (mean age: 55, 43% male) and 25,177 controls (mean age: 56, 45% male). We found a positive association between BMI and the risk of a T2D diagnosis. The strength of this association increased with BMI category (RR [95% confidence interval]: overweight, 1.5 [1.4-1.6]; Obesity Class I, 2.5 [2.3-2.6]; Obesity Class II, 3.6 [3.4-3.8]; Obesity Class III, 5.1 [4.7-5.5]).

CONCLUSIONS

BMI is strongly and independently associated with the risk of being diagnosed with T2D. The incremental association of BMI category on the risk of T2D is stronger for people with a higher BMI relative to people with a lower BMI.

Hypoglycemia as a driver of cardiovascular risk in diabetes

Severe hypoglycemia in patients with diabetes is associated with increased risk of adverse cardiovascular events and death. Recent large randomized clinical trials in individuals with type 2 diabetes have shown that intensive glycemic control may result in increased mortality, and hypoglycemia has been investigated as a possible cause. Acute hypoglycemia is a proarrhythmic, proinflammatory, and prothrombotic state, and several mechanisms have been proposed to explain how hypoglycemia might increase cardiovascular morbidity and mortality. However, data from large clinical trials do not provide strong evidence to establish hypoglycemia as a cause of increased mortality. Severe hypoglycemia is also a marker of frailty and a predictor of adverse outcomes in patients with diabetes. Individualized therapy should be the goal in patients with diabetes to avoid severe hypoglycemia and any related adverse outcomes.

Assessing achievement and maintenance of glycemic control by patients initiating basal insulin

OBJECTIVE

Describe characteristics of diabetic patients who initiated basal insulin and assess their glycemic control.

RESEARCH DESIGN AND METHODS

Physician encounters in the General Electric EMR Database (2005-2010) were assessed for patients with type II diabetes (T2DM) who initiated basal insulin between February 2006 and August 2009, with initiation defined as no prescription record of insulin in prior 15 months. Patients were followed for an average 2.5 years after insulin initiation. The proportion and time to achieving HbA1c ≤ 7% ('goal') were assessed. Among patients who reached goal, the proportion and time to HbA1c increasing above 7% were analyzed. Cox proportional hazard models were estimated to identify predictors of HbA1c goal achievement and goal sustainability.

RESULTS

Basal insulin initiators with T2DM (n = 13,373) were on average 60 years old, 50.5% were females, and 59.5% had HbA1c > 8%; 5840 (44%) patients reached goal within one year and 7699 (58%) reached goal during the ∼2.5-year follow-up. Being older, white or male, lower baseline HbA1c values, and no OAD use before insulin initiation were associated with significantly higher rates of reaching goal. Among patients who reached goal, 57.6% could not sustain the goal. Being Hispanic, higher baseline HbA1c values, and baseline OAD use were associated with significantly lower rates of goal sustainment.

CONCLUSION

A high proportion of T2DM patients did not have adequate glycemic control after initiating basal insulin. Various factors existing prior to insulin initiation were related to successful treatment of T2DM. Further research on how to improve glycemic control is encouraged.

Chronic Inhibition of cGMP phosphodiesterase 5A improves diabetic cardiomyopathy: a randomized, controlled clinical trial using magnetic resonance imaging with myocardial tagging

BACKGROUND

cGMP phosphodiesterase type 5 protein is upregulated in myocardial hypertrophy. However, it has never been ascertained whether phosphodiesterase type 5 inhibition exerts an antiremodeling effect in nonischemic heart disease in humans. We explored the cardioreparative properties of a selective phosphodiesterase type 5 inhibitor, sildenafil, in a model of diabetic cardiomyopathy.

METHODS AND RESULTS

Fifty-nine diabetic men (60.3 ± 7.4 years) with cardiac magnetic resonance imaging consistent with nonischemic, nonfailing diabetic cardiomyopathy (reduced circumferential strain [σ], -12.6 ± 3.1; increased left ventricular [LV] torsion [θ], 18.4 ± 4.6°; and increased ratio of LV mass to volume, 2.1 ± 0.5 g/mL) were randomized to receive sildenafil or placebo (100 mg/d). At baseline, the metabolic indices were correlated with torsion, strain, N-terminal pro-B-type natriuretic peptide, vascular endothelial growth factor, monocyte chemotactic protein-1, and blood pressure. After 3 months, sildenafil produced a significant improvement compared with placebo in LV torsion (Δθ: sildenafil, -3.89 ± 3.11° versus placebo, 2.13 ± 2.35°; P<0.001) and strain (Δσ: sildenafil, -3.30 ± 1.86 versus placebo, 1.22 ± 1.84; P<0.001). Sildenafil-induced improvement of LV contraction was accompanied by consistent changes in chamber geometry and performance, with a 6.5 ± 11 improvement in mass-to-volume ratio over placebo (P=0.021). Monocyte chemotactic protein-1 and transforming growth factor-β were the only markers affected by active treatment (Δmonocyte chemotactic protein-1: -75.30 ± 159.28 pg/mL, P=0.032; Δtransforming growth factor-β: 5.26 ± 9.67 ng/mL, P=0.009). No changes were found in endothelial function, afterload, or metabolism.

CONCLUSIONS

The early features of diabetic cardiomyopathy are LV concentric hypertrophy associated with altered myocardial contraction dynamics. Chronic phosphodiesterase type 5 inhibition, at this stage, has an antiremodeling effect, resulting in improved cardiac kinetics and circulating markers. This effect is independent of any other vasodilatory or endothelial effects and is apparently exerted through a direct intramyocardial action.