Lack of correlation between the optimal glycaemic control and coronary micro vascular dysfunction in patients with diabetes mellitus: a cross sectional study

Cardiovascular Determinants of Aerobic Exercise Capacity in Adults With Type 2 Diabetes

OBJECTIVE

To assess the relationship between subclinical cardiac dysfunction and aerobic exercise capacity (peak VO₂) in adults with type 2 diabetes (T2D), a group at high risk of developing heart failure.

RESEARCH DESIGN AND METHODS

Cross-sectional study. We prospectively enrolled a multiethnic cohort of asymptomatic adults with T2D and no history, signs, or symptoms of cardiovascular disease. Age-, sex-, and ethnicity-matched control subjects were recruited for comparison. Participants underwent bioanthropometric profiling, cardiopulmonary exercise testing, and cardiovascular magnetic resonance with adenosine stress perfusion imaging. Multivariable linear regression analysis was undertaken to identify independent associations between measures of cardiovascular structure and function and peak VO₂.

RESULTS

A total of 247 adults with T2D (aged 51.8 ± 11.9 years, 55% males, 37% black or south Asian ethnicity, HbA_1c 7.4 ± 1.1% [57 ± 12 mmol/mol], and duration of diabetes 61 [32-120] months) and 78 control subjects were included. Subjects with T2D had increased concentric left ventricular remodeling, reduced myocardial perfusion reserve (MPR), and markedly lower aerobic exercise capacity (peak VO₂ 18.0 ± 6.6 vs. 27.8 ± 9.0 mL/kg/min; P < 0.001) compared with control subjects. In a multivariable linear regression model containing age, sex, ethnicity, smoking status, and systolic blood pressure, only MPR (β = 0.822; P = 0.006) and left ventricular diastolic filling pressure (E/e') (β = -0.388; P = 0.001) were independently associated with peak VO₂ in subjects with T2D.

CONCLUSIONS

In a multiethnic cohort of asymptomatic people with T2D, MPR and diastolic function are key determinants of aerobic exercise capacity, independent of age, sex, ethnicity, smoking status, or blood pressure.

Cardiologist and Diabetologist crosstalk in the era of cardiovascular outcome trials of novel glucose-lowering drugs

The prevalence of type 2 diabetes continues to increase and cardiovascular (CV) diseases remain the leading cause of death in diabetic patients. Diabetologists and Cardiologists have to work together in order to provide the best management to these patients. After years of disappointing studies showing no reduction of CV events with strict glycaemic control, some of the novel glucose-lowering drugs (GLDs) seem to offer a new approach to tackle the problem, since the CV outcome trials (CVOTs-D) of liraglutide, semaglutide, empagliflozin and canagliflozin have demonstrated not only their CV safety but also their efficacy in the reduction of CV morbidity and mortality. Along with the initial enthusiasm, concerns have been raised about the economical sustainability of long-term therapies considering higher costs of new molecules relative to the traditional ones. As expenses in the medical field are on the rise, healthcare systems need to balance the positive impact of an intervention and its overall cost. This review is meant to offer the Cardiologists a different point of view on the positive influence of GLDs, in the light of the main trials in the CV fields they are familiar with. The purpose of this article is to critically review the magnitude of the CVOTs-D results by the analysis of their statistical determinants, to establish the extent of the GLDs positive impact on patients with both diabetes and CV disease. The analysis has been performed taking into account models and statistical determinants used in the main landmark cardiology trials. It is fundamental to translate the result of CVOTs-D in clinical practice: the interdisciplinary crosstalk between the Cardiologist and Diabetologist is of paramount importance in order to fully exploit the power of the new available pharmacological strategies.

Arginase inhibition improves endothelial function in patients with type 2 diabetes mellitus despite intensive glucose-lowering therapy

BACKGROUND

Arginase is implicated in the pathogenesis behind endothelial dysfunction in type 2 diabetes mellitus (T2DM) by its inhibition of nitric oxide formation. Strict glycaemic control is not sufficient to improve endothelial function or cardiovascular outcomes in patients with T2DM, thus other treatment strategies are needed. We hypothesized that arginase inhibition improves endothelial function beyond glucose-lowering therapy following glucose optimization in patients with poorly controlled T2DM.

METHODS AND RESULTS

Endothelial function was evaluated in 16 patients with poorly controlled T2DM (visit 1) and 16 age-matched controls using venous occlusion plethysmography. T2DM patients were re-evaluated (visit 2) after intensive glucose-lowering regimen. Endothelium-dependent (EDV) and -independent (EIDV) vasodilatations were evaluated before and after 120 min intra-arterial infusion of the arginase inhibitor N(ω)-hydroxy-nor-L-arginine (nor-NOHA). HbA1c was reduced from 87 ± 17 (visit 1) to 65 ± 11 mmol mol^-1 (visit 2, P < 0.001). Basal EDV, but not EIDV, was significantly lower in patients with T2DM than in healthy subjects (P < 0.05). EDV and EIDV were unaffected by glucose-lowering regimen in patients with T2DM. Arginase inhibition enhanced EDV in T2DM patients both at visit 1 and visit 2 (P < 0.01). There was no difference in improvement in EDV between the two occasions. EIDV was unaltered by nor-NOHA in T2DM at visit 1, but was slightly improved at visit 2.

CONCLUSIONS

Arginase inhibition improves endothelial function in patients with poorly controlled T2DM, which is maintained following glucose optimization. Thus, arginase inhibition is a promising therapeutic target beyond glucose lowering for improving endothelial function in T2DM patients.

Diabetes, cardiovascular disease and the microcirculation

Cardiovascular disease (CVD) is the leading cause of mortality in people with type 2 diabetes mellitus (T2DM), yet a significant proportion of the disease burden cannot be accounted for by conventional cardiovascular risk factors. Hypertension occurs in majority of people with T2DM, which is substantially more frequent than would be anticipated based on general population samples. The impact of hypertension is considerably higher in people with diabetes than it is in the general population, suggesting either an increased sensitivity to its effect or a confounding underlying aetiopathogenic mechanism of hypertension associated with CVD within diabetes. In this contribution, we aim to review the changes observed in the vascular tree in people with T2DM compared to the general population, the effects of established anti-diabetes drugs on microvascular outcomes, and explore the hypotheses to account for common causalities of the increased prevalence of CVD and hypertension in people with T2DM.

Coronary microvascular dysfunction in diabetes mellitus

The significance, mechanisms and consequences of coronary microvascular dysfunction associated with diabetes mellitus are topics into which we have insufficient insight at this time. It is widely recognized that endothelial dysfunction that is caused by diabetes in various vascular beds contributes to a wide range of complications and exerts unfavorable effects on microcirculatory regulation. The coronary microcirculation is precisely regulated through a number of interconnected physiological processes with the purpose of matching local blood flow to myocardial metabolic demands. Dysregulation of this network might contribute to varying degrees of pathological consequences. This review discusses the most important findings regarding coronary microvascular dysfunction in diabetes from pre-clinical and clinical perspectives.

The impact of cardiovascular co-morbidities and duration of diabetes on the association between microvascular function and glycaemic control

BACKGROUND

Good glycaemic control in type 2 diabetes (T2DM) protects the microcirculation. Current guidelines suggest glycaemic targets be relaxed in advanced diabetes. We explored whether disease duration or pre-existing macrovascular complications attenuated the association between hyperglycaemia and microvascular function.

METHODS

743 participants with T2DM (n = 222), cardiovascular disease (CVD = 183), both (n = 177) or neither (controls = 161) from two centres in the UK, underwent standard clinical measures and endothelial dependent (ACh) and independent (SNP) microvascular function assessment using laser Doppler imaging.

RESULTS

People with T2DM and CVD had attenuated ACh and SNP responses compared to controls. This was additive in those with both (ANOVA p < 0.001). In regression models, cardiovascular risk factors accounted for attenuated ACh and SNP responses in CVD, whereas HbA₁c accounted for the effects of T2DM. HbA₁c was associated with ACh and SNP response after adjustment for cardiovascular risk factors (adjusted standardised beta (β) -0.096, p = <0.008 and -0.135, p < 0.001, respectively). Pre-existing CVD did not modify this association (β -0.099; p = 0.006 and -0.138; p < 0.001, respectively). Duration of diabetes accounted for the association between HbA₁c and ACh (β -0.043; p = 0.3), but not between HbA₁c and SNP (β -0.105; p = 0.02).

CONCLUSIONS

In those with T2DM and CVD, good glycaemic control is still associated with better microvascular function, whereas in those with prolonged disease this association is lost. This suggests duration of diabetes may be a better surrogate for "advanced disease" than concomitant CVD, although this requires prospective validation.

PRotective Effect on the coronary microcirculation of patients with DIabetes by Clopidogrel or Ticagrelor (PREDICT): study rationale and design. A randomized multicenter clinical trial using intracoronary multimodal physiology

Background

In diabetic patients a predisposed coronary microcirculation along with a higher risk of distal particulate embolization during primary percutaneous intervention (PCI) increases the risk of peri-procedural microcirculatory damage. However, new antiplatelet agents, in particular Ticagrelor, may protect the microcirculation through its adenosine-mediated vasodilatory effects.

Methods

PREDICT is an original, prospective, randomized, multicenter controlled study designed to investigate the protective effect of Ticagrelor on the microcirculation during PCI in patient with diabetes mellitus type 2 or pre-diabetic status. The primary endpoints of this study aim to test (i) the decrease in microcirculatory resistance with antiplatelet therapy (Ticagrelor > Clopidogrel; mechanistic effect) and (ii) the relative microcirculatory protection of Ticagrelor compared to Clopidogrel during PCI (Ticagrelor < Clopidogrel; protective effect).

Conclusions

PREDICT will be the first multicentre clinical trial to test the adenosine-mediated vasodilatory effect of Ticagrelor on the microcirculation during PCI in diabetic patients. The results will provide important insights into the prospective beneficial effect of this drug in preventing microvascular impairment related to PCI (http://www.clinicaltrials.gov No. NCT02698618).

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0543-5) contains supplementary material, which is available to authorized users.

Continued efforts to translate diabetes cardiovascular outcome trials into clinical practice

Diabetic patients suffer from a high rate of cardiovascular events and such risk increases with HbA1c. However, lowering HbA1c does not appear to yield the same benefit on macrovascular endpoints, as observed for microvascular endpoints. As the number of glucose-lowering medications increases, clinicians have to consider several open questions in the management of type 2 diabetes, one of which is the cardiovascular risk profile of each regimen. Recent placebo-controlled cardiovascular outcome trials (CVOTs) have responded to some of these questions, but careful interpretation is needed. After general disappointment around CVOTs assessing safety of DPP-4 inhibitors (SAVOR, TECOS, EXAMINE) and the GLP-1 receptor agonist lixisenatide (ELIXA), the EMPA-REG Outcome trial and the LEADER trial have shown superiority of the SGLT2-I empagliflozin and the GLP-1RA liraglutide, respectively, on the 3-point MACE outcome (cardiovascular death, non-fatal myocardial infarction or stroke) and cardiovascular, as well as all-cause mortality. While available mechanistic studies largely support a cardioprotective effect of GLP-1, the ability of SGLT2 inhibitor(s) to prevent cardiovascular death was unexpected and deserves future investigation. We herein review the results of completed CVOTs of glucose-lowering medications and suggest a possible treatment algorithm based on cardiac and renal co-morbidities to translate CVOT findings into clinical practice.

The prevalence of diabetes, hypertension and obesity among immigrants from East Africa and the former Soviet Union: a retrospective comparative 30-year cohort study

Background

Previous studies have reported an increasing prevalence of metabolic abnormalities in immigrants who moved from low-cardiovascular-risk regions to Western countries, but little is known about time trends following immigration.

Methods

A retrospective cohort study of immigrants from Ethiopia in east Africa (EAI), the former Soviet Union (FSUI) and native-born Israelis (NBI) over a 35-year period. EAI were divided into three groups by date of immigration. Associations between ethnicity, age, sex and metabolic risk factors were assessed using logistic regression models.

Results

The study included 58,901 individuals (20,768 EAI, 20,507 FSUI, and 17,626 NBI). The multivariate odds ratios (OR) for diabetes were 2.4 (95 % CI 2.1–2.6), 2.1 (95 % CI 1.9–2.2) and 1.5 (95 % CI 1.3–1.7), respectively, for the three waves of EAI immigrations (P < 0.001 for trend) and 1.1 (95 % CI 0.9–1.2) for FSUI. For hypertension, the corresponding ORs were 1.8 (95 % CI 1.6–1.9), 1.4 (95 % CI 1.3–1.5), and 1.1 (95 % CI 0.9–1.2), respectively (P < 0.001) for EAI, and 2.1 (95 % CI 1.9–2.2) for FSUI. For obesity the ORs were −0.5 (95 % CI 0.4–0.6), 0.5 (95 % CI 0.4–0.6), and 0.3 (95 % CI 0.2–0.3), respectively (P < 0.001) for EAI, and 1.2 (95 % CI 1.1–1.3) for FSUI. The prevalence of diabetes in NBI with a BMI of 30 was identical to a BMI of 23.4 for EAI and 28.9 for FSUI.

Conclusions

The prevalence of diabetes and hypertension was higher in EAI and increased over the years, despite a lower prevalence of obesity. It exceeded the prevalence rates in NBI.