Prevalence and predictors of abnormal arterial function in statin-treated type 2 diabetes mellitus patients

Albuminuria rather than glomerular filtration rate is associated with vascular endothelial function in patients with type 2 diabetes

AIMS

Albuminuria and reduced glomerular filtration rate (GFR) are manifestations of diabetic kidney disease and are both shown to be associated with cardiovascular outcomes. However, the differential association of albuminuria and reduced GFR with endothelial dysfunction, an early feature of atherosclerotic vascular damage, remains unclear. In this study, we investigated the association between albuminuria or estimated GFR (eGFR) and flow-mediated dilatation (FMD), a marker of endothelial function, in patients with type 2 diabetes.

METHODS

This study included 633 patients with type 2 diabetes. The FMD of the brachial artery was measured by ultrasonography. Albuminuria was evaluated by urinary albumin-to-creatinine ratio (ACR).

RESULTS

The mean FMD and eGFR, and the median value of ACR were 6.7%, 66.5 mL/min/1.73m² and 12.5 mg/g creatinine, respectively. Impaired FMD was found in patients with advanced stages of chronic kidney disease based on both GFR and albuminuria categories. Multivariate analysis after adjusting for potential confounders revealed that ACR, but not eGFR, was significantly and inversely associated with FMD.

CONCLUSIONS

Albuminuria is associated with FMD, independently of traditional cardiovascular risk factors in patients with type 2 diabetes. This study suggests a close relationship between albuminuria, rather than reduced GFR, and endothelial dysfunction in type 2 diabetes.

Impaired endothelial function and arterial stiffness in patients with type 2 diabetes - The effect of a very low-dose combination of fluvastatin and valsartan

AIM

Patients with type 2 diabetes are at increased cardiovascular risk. The aim was to explore whether the impaired arterial wall characteristics typical of these patients could be improved by the unique beneficial effects of a very low-dose combination of fluvastatin and valsartan (low-flu/val).

METHODS

Forty middle-aged males (50.4±6.1years) with type 2 diabetes were recruited to a double-blind, randomized study. Patients (N=20) received low-flu/val (10/20mg) or placebo (N=20) over 30days in addition to their regular therapy. Brachial artery flow mediated dilation (FMD), common carotid artery pulse wave velocity (PWV) and β-stiffness were assessed before and after treatment, and 3 and 6months after treatment discontinuation. The treatment was then repeated.

RESULTS

Arterial wall characteristics significantly improved. After 30days of intervention, FMD increased from 2.4±0.3 to 4.2±0.3 (p<0.001), PWV decreased from 6.4±0.1 to 5.8±0.2 (p<0.001) and β stiffness decreased from 7.8±0.4 to 6.7±0.4 (p<0.001). Lipids and arterial pressure did not change. After treatment discontinuation, the beneficial effects decreased over the following months. The repetition of treatment completely regained the initial benefits. No changes were observed in the placebo group.

CONCLUSIONS

Low-flu/val added on-top of optimal therapy substantially improves arterial wall characteristics in patients with type 2 diabetes.

GLP-1 promotes angiogenesis in human endothelial cells in a dose-dependent manner, through the Akt, Src and PKC pathways

INTRODUCTION

Novel anti-diabetic medications that mimic or augment the physiological actions of GLP-1 improve cardiovascular risk factors in diabetics and GLP-1 has been proposed to have a beneficial role in the cardiovascular system. GLP-1 may have a direct cardioprotective role by decreasing infarct size and protecting from ischemia-reperfusion injury while prolonging survival in rodent models. The mechanisms underlying these observations remain largely unknown. In vitro studies suggest that GLP-1 may promote endothelial cell proliferation, but no study to date has evaluated a potential direct effect of GLP-1 on angiogenesis.

SPECIFIC AIM

To evaluate whether GLP-1 affects angiogenesis in humans and to elucidate underlying molecular mechanisms.

MATERIAL AND METHODS

We utilized a 3D culture system where spherules of human umbilical vein endothelial cells (HUVECs) embedded in a collagen scaffold were treated with escalating doses of human recombinant GLP-1 (50-2000 nmol/L) and the formation of new vessels was observed and quantified. Signaling inhibitors were utilized to identify molecular pathways through which GLP-1 promotes angiogenesis.

RESULTS

We demonstrate that GLP-1 promotes angiogenesis in a dose-dependent manner. The maximum effect on angiogenesis was observed at a GLP-1 dose of 500 nmol/L, while increased angiogenesis occurred in response to doses ranging from 200 nmol/L to 1000 nmol/L. Pre-treatment of the system with Akt inhibitor IV, Bisindolylmaleimide (PKC inhibitor) and src inhibitor I resulted in a significant decrease of the GLP-1 induced angiogenesis.

CONCLUSIONS

This is the first study to demonstrate that GLP-1 promotes angiogenesis in a HUVEC three dimensional in vitro model. This effect requires pharmacological doses and is mediated through the Akt, PKC and src pathways.