Endothelial perturbation: a link between non-dipping and retinopathy in type 2 diabetes?

Blood Pressure, Congestion and Heart Failure with Preserved Ejection Fraction Among Patients with and Without Type 2 Diabetes Mellitus. A Cluster Analysis Approach from the Observational Registry DICUMAP

INTRODUCTION

The association of patients with heart failure (HF) and preserved ejection fraction (HFpEF) and with type 2 diabetes mellitus (T2DM) is strong and related additionally to blood pressure (BP).

AIMS

To analyze distinctive clinical profiles among patients with HFpEF both with and without T2DM.

METHODS

The study was based on a Spanish National Registry (multicenter and prospective) of patients with HF (DICUMAP), that enrolled outpatients with HF who underwent an ambulatory BP monitoring (ABPM) and then were followed-up for 1 year. We categorized patients according to the presence/absence of T2DM then building different clusters based on K-medoids algorithm.

RESULTS

103 patients were included. T2DM was present in 44.7%. The patients with T2DM were grouped into two clusters and those without T2DM into three. All patients with T2DM had kidney disease and anemia. Among them, cluster 2 had higher systolic blood pressure and pulse pressure (PP) with a bad outcome (p = 0.03) regarding HF mortality and readmissions, influenced by eGFR (HR 0.93, 95% CI 0.97-0.87, p = 0.04), and hemoglobin (HR 0.65, 95% CI 0.71-0.63, p = 0.03). Among those without T2DM, cluster 3 had a pathological ABPM pattern with the highest PP, cluster 4 was slightly similar to cluster 2, and cluster 5 expressed a more benign pattern without differences on both, HF mortality and readmissions.

CONCLUSIONS

Patients with HFpEF and T2DM expressed two different profiles depending on neurohormonal activation and arterial stiffness with prognostic implications. Patients without T2DM showed three profiles depending on ABPM pattern, kidney disease and PP without prognostic repercussion.

Microbiota-governed microRNA-204 impairs endothelial function and blood pressure decline during inactivity in db/db mice

An impaired decline in blood pressure at rest is typical in people with diabetes, reflects endothelial dysfunction, and increases the risk of end-organ damage. Here we report that microRNA-204 (miR-204) promotes endothelial dysfunction and impairment in blood pressure decline during inactivity. We show that db/db mice overexpress miR-204 in the aorta, and its absence rescues endothelial dysfunction and impaired blood pressure decline during inactivity despite obesity. The vascular miR-204 is sensitive to microbiota, and microbial suppression reversibly decreases aortic miR-204 and improves endothelial function, while the endothelial function of mice lacking miR-204 remained indifferent to the microbial alterations. We also show that the circulating miR-122 regulates vascular miR-204 as miR-122 inhibition decreases miR-204 in endothelial cells and aorta. This study establishes that miR-204 impairs endothelial function, promotes impairment in blood pressure decline during rest, and opens avenues for miR-204 inhibition strategies against vascular dysfunction.

Impaired nocturnal blood pressure dipping in patients with type 2 diabetes mellitus

Hypertension is a common comorbidity of type 2 diabetes mellitus (T2DM). Both conditions are associated with an increased cardiovascular risk, which is reduced by tight blood pressure (BP) and glycemic control. However, nondipping BP status continues to be an enduring cardiovascular risk factor in T2DM. Cardiovascular autonomic neuropathy and endothelial dysfunction have been proposed as potential mechanisms. This study tested the hypothesis that microvascular disease rather than cardiovascular autonomic neuropathy interferes with the physiological nocturnal BP reduction. Cardiovascular autonomic function and baroreflex sensitivity were determined in 22 type 2 diabetic patients with (DM+) and 23 diabetic patients without (DM-) manifest microvascular disease. BP dipping status was assessed from 24-hour ambulatory BP measurements. Sixteen nondiabetic subjects served as controls (CTRL). Cardiovascular autonomic function was normal in all subjects. Baroreflex sensitivity was lower in DM- compared with CTRL (7.7 ± 3.3 vs. 12.3 ± 8.3 ms·mm Hg^-1; P < 0.05) and was further reduced in DM + (4.6 ± 2.0 ms·mm Hg^-1; P < 0.01 vs. DM- and CTRL). The nocturnal decline in systolic and diastolic BP was blunted in DM- (12% and 14% vs. 17% and 19% in CTRL; P < 0.05) and even more so in DM+ (8% and 11%; P < 0.05 vs. DM- and P < 0.001 vs. CTRL). A nocturnal reduction in pulse pressure was observed in CTRL and DM- but not in DM+ (P < 0.05 vs. DM- and P < 0.01 vs. CTRL). In T2DM, progression of microvascular disease interferes with the normal nocturnal BP decline and coincides with a persistently increased pulse pressure and reduced baroreflex sensitivity, contributing to their increased cardiovascular risk.

Biomarkers in Diabetic Retinopathy

There is a global diabetes epidemic correlating with an increase in obesity. This coincidence may lead to a rise in the prevalence of type 2 diabetes. There is also an as yet unexplained increase in the incidence of type 1 diabetes, which is not related to adiposity. Whilst improved diabetes care has substantially improved diabetes outcomes, the disease remains a common cause of working age adult-onset blindness. Diabetic retinopathy is the most frequently occurring complication of diabetes; it is greatly feared by many diabetes patients. There are multiple risk factors and markers for the onset and progression of diabetic retinopathy, yet residual risk remains. Screening for diabetic retinopathy is recommended to facilitate early detection and treatment. Common biomarkers of diabetic retinopathy and its risk in clinical practice today relate to the visualization of the retinal vasculature and measures of glycemia, lipids, blood pressure, body weight, smoking, and pregnancy status. Greater knowledge of novel biomarkers and mediators of diabetic retinopathy, such as those related to inflammation and angiogenesis, has contributed to the development of additional therapeutics, in particular for late-stage retinopathy, including intra-ocular corticosteroids and intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') agents. Unfortunately, in spite of a range of treatments (including laser photocoagulation, intraocular steroids, and anti-VEGF agents, and more recently oral fenofibrate, a PPAR-alpha agonist lipid-lowering drug), many patients with diabetic retinopathy do not respond well to current therapeutics. Therefore, more effective treatments for diabetic retinopathy are necessary. New analytical techniques, in particular those related to molecular markers, are accelerating progress in diabetic retinopathy research. Given the increasing incidence and prevalence of diabetes, and the limited capacity of healthcare systems to screen and treat diabetic retinopathy, there is need to reliably identify and triage people with diabetes. Biomarkers may facilitate a better understanding of diabetic retinopathy, and contribute to the development of novel treatments and new clinical strategies to prevent vision loss in people with diabetes. This article reviews key aspects related to biomarker research, and focuses on some specific biomarkers relevant to diabetic retinopathy.

Association between glycemic control and morning blood pressure surge with vascular endothelial dysfunction in type 2 diabetic patients

OBJECTIVE

Morning blood pressure surge (MBPS) is an independent predictor of cardiovascular events. However, little is known about the association between glycemic control and MBPS, and its effect on vascular injury in patients with type 2 diabetes mellitus (T2DM). The current study examined the association between glycemic control and MBPS, and the involvement of MBPS in the development of vascular dysfunction in T2DM patients.

RESEARCH DESIGN AND METHODS

We examined MBPS in T2DM patients (25 male patients/25 female patients; mean age, 60.1 ± 13.2 years; n = 50) using 24-h ambulatory blood pressure monitoring, and assessed vascular function by brachial artery flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD).

RESULTS

HbA1c (ρ = 0.373, P = 0.009) and triglyceride (TG) (ρ = 0.375, P = 0.009) levels correlated significantly and positively with MBPS. In multiple regression analysis, including TG and HbA1c levels in addition to age and 24-h systolic blood pressure (SBP) as independent variables, HbA1c (β = 0.328, P = 0.016) and TG (β = 0.358, P = 0.014) were associated significantly in a positive manner with MBPS. In a noninsulin user, when homeostasis model assessment ratio (HOMA-R) was included in place of TG, HOMA-R emerged as a significant factor. MBPS (ρ = -0.289, P = 0.043) and HbA1c (ρ = -0.301, P = 0.035) correlated significantly and negatively with FMD, whereas 24-h SBP correlated with both FMD (ρ = -0.359, P = 0.012) and NMD (ρ = -0.478, P = 0.004). In multiple regression analysis, including age, gender, 24-h SBP, MBPS, LDL cholesterol, and HbA1c, MBPS (β = -0.284, P = 0.044) alone associated significantly in a negative manner with FMD, but not with NMD.

CONCLUSIONS

The current study demonstrated that poor glycemic control and insulin resistance are independently associated with the occurrence of MBPS in T2DM patients, which might be significantly associated with endothelial dysfunction.

Ambulatory pulse pressure, decreased nocturnal blood pressure reduction and progression of nephropathy in type 2 diabetic patients

AIMS/HYPOTHESIS

We followed type 2 diabetic patients over a long period to evaluate the predictive value of ambulatory pulse pressure (PP) and decreased nocturnal BP reduction (non-dipping) for nephropathy progression.

METHODS

Type 2 diabetic patients (n = 112) were followed for an average of 9.5 (range 0.5-14.5) years. At baseline, all patients underwent 24 h ambulatory BP measurement. Urinary albumin excretion rate was evaluated by three urinary albumin:creatinine ratio measurements at baseline and follow-up.

RESULTS

At baseline, patients who subsequently progressed to a more advanced nephropathy stage (n = 35) had reduced diastolic night/day BP variation and higher 24 h systolic BP and PP values; they also had more advanced nephropathy and were more likely to smoke than those with no progression of nephropathy (n = 77). In a Cox regression analysis, independent predictors of nephropathy progression were 24 h PP (p < 0.01), diastolic night:day BP ratio (p = 0.02) and smoking (p = 0.02). The adjusted hazards ratio (95% CI) for each mmHg increment in 24 h PP was 1.04 (1.01-1.07), whereas the adjusted hazards ratio (95% CI) for each 1% increase in diastolic night:day BP ratio was 1.06 (1.01-1.11). Only one of 33 patients (3.0%) with both a diastolic night:day BP ratio and a 24 h PP below the median progressed, whereas 17 of 32 patients (53.1%) with both a diastolic night:day BP ratio and a 24 h PP equal to or above the median progressed to a more advanced nephropathy stage (p < 0.001).

CONCLUSIONS/INTERPRETATION

Ambulatory PP, impaired nocturnal BP decline and smoking are strong, independent predictors of nephropathy progression in type 2 diabetic patients.