Peripheral arterial disease in diabetes mellitus type 1 and type 2: are there different risk factors?

Diabetic Vasculopathy: Molecular Mechanisms and Clinical Insights

Clinical and basic studies have documented that both hyperglycemia and insulin-resistance/hyperinsulinemia not only constitute metabolic disorders contributing to cardiometabolic syndrome, but also predispose to diabetic vasculopathy, which refers to diabetes-mellitus-induced microvascular and macrovascular complications, including retinopathy, neuropathy, atherosclerosis, coronary artery disease, hypertension, and peripheral artery disease. The underlying molecular and cellular mechanisms include inappropriate activation of the renin angiotensin-aldosterone system, mitochondrial dysfunction, excessive oxidative stress, inflammation, dyslipidemia, and thrombosis. These abnormalities collectively promote metabolic disorders and further promote diabetic vasculopathy. Recent evidence has revealed that endothelial progenitor cell dysfunction, gut dysbiosis, and the abnormal release of extracellular vesicles and their carried microRNAs also contribute to the development and progression of diabetic vasculopathy. Therefore, clinical control and treatment of diabetes mellitus, as well as the development of novel therapeutic strategies are crucial in preventing cardiometabolic syndrome and related diabetic vasculopathy. The present review focuses on the relationship between insulin resistance and diabetes mellitus in diabetic vasculopathy and related cardiovascular disease, highlighting epidemiology and clinical characteristics, pathophysiology, and molecular mechanisms, as well as management strategies.

Limb and cardiovascular event risk in type 1 and 2 diabetic patients with peripheral artery disease

Background: Peripheral artery disease (PAD) is a risk factor for adverse limb events (LE) and cardiovascular events (CVE) that coexists with type 1 (T1) and 2 (T2) diabetes mellitus (DM). Little is known about comparative risk of LE and CVE in T1/T2 DM patients with PAD. Patients and methods: We queried our database of 40,144 patients ≥18 years old who underwent ankle brachial index (ABI) measurement from 01/1996-02/2020. We isolated T1/T2 DM patients with PAD diagnosed by ankle brachial index (ABI; low [<1.0] or elevated [>1.4]) and retrieved demographics including glycated hemoglobin (HbA1c). Primary outcomes were LE (critical limb ischemia/vascular amputation) and CVE (myocardial infarction/ischemic stroke). All-cause mortality was a secondary outcome. Multivariable Cox proportional regression yielded hazard ratios (HR) with 95% confidence intervals (CI) after adjusting for pertinent risk factors including age, hypertension, hyperlipidemia, smoking, and HbA1c. Results: Our study found 10,156 patients with PAD and DM (34% T1DM, 66% T2DM) with median follow-up time 34 mo (IQR 85 mo). T1DM patients were younger than T2DM (mean age 67 vs. 70 years), with higher median HbA1c (7.7 [IQR 1.9] vs. 6.7% [IQR 1.6]), and more prevalent hypertension, hyperlipidemia, CAD, and CKD. Antiplatelet and statin use was equivocal. Elevated ABI was more common in T1DM (47 vs. 28%). LE occurred in 23% and CVE in 12% patients. LE risk was higher in T1 than T2 DM patients (HR 1.58 [95% CI 1.44, 1.73], p<0.0001), but CVE and all-cause mortality were equivocal. These observations were preserved across ABI and HbA1c subgroup analyses. Conclusions: PAD patients with T1DM had a higher LE risk than those with T2DM, even after adjustment for glycemic control and pertinent risk factors, but CVE risk and all-cause mortality were equivocal. These data suggest a potential role for more intensive LE risk modification in PAD patients with T1DM, but further investigation is needed.

Association Between HbA1c Levels and Diabetic Peripheral Neuropathy: A Case-Control Study of Patients with Type 2 Diabetes Using Claims Data

BACKGROUND

Evidence on the efficacy of glycemic control for diabetic peripheral neuropathy (DPN) is limited in patients with type 2 diabetes mellitus. Despite the known relationship between hemoglobin A1c (HbA1c) and DPN, the parameters (e.g., mean values or variability) that play an important role have not been elucidated.

OBJECTIVE

The objective of this study was to explore factors associated with DPN, including long-term HbA1c parameters, among patients with type 2 diabetes, in a large-scale longitudinal study.

METHODS

We conducted a case-control study using a medical claims database. We extracted data of patients with type 2 diabetes and disease records of DPN (indicating that they received treatment for DPN) and those without DPN records (controls), and matched for age, sex, index year, and duration since the first type 2 diabetes record. A logistic regression analysis was performed to explore factors associated with DPN, and a receiver-operating characteristic analysis to estimate the optimal mean HbA1c target.

RESULTS

Of 1,792,037 patients with type 2 diabetes, data from 1632 patients (816 per group) were analyzed. The mean HbA1c levels in the 3-year observation period were 7.2 ± 1.0% in the DPN group and 6.9 ± 1.1% in the control group. Elevated 3-year mean HbA1c levels were significantly associated with DPN records (adjusted odds ratio: 1.23, 95% confidence interval 1.06-1.42), while HbA1c variability was not significantly associated. The mean HbA1c levels that discriminated between patients with and without DPN records were 6.5% (unadjusted) and 7.1% (adjusted).

CONCLUSIONS

The development or progression of DPN in patients with type 2 diabetes was associated with the 3-year mean HbA1c level in real-world data.

High Normal Urinary Albumin-Creatinine Ratio Is Associated With Hypertension, Type 2 Diabetes Mellitus, HTN With T2DM, Dyslipidemia, and Cardiovascular Diseases in the Chinese Population: A Report From the REACTION Study

Background

Albuminuria has been widely considered a risk factor for cardiovascular diseases (CVDs), which is associated with hypertension (HTN), type 2 diabetes mellitus (T2DM), HTN with T2DM, and dyslipidemia. However, the associations between albuminuria and HTN, T2DM, HTN with T2DM, dyslipidemia, and CVDs are still unclear. Thus, this study aimed to explore the association of albuminuria thoroughly, especially within the normal range, with the abovementioned diseases in the Chinese population.

Methods

This study included 40,188 participants aged over 40 years from seven centers across China. Urinary albumin-creatinine ratio (UACR) was firstly divided into the ≥30-mg/g group, indicating kidney damage, and <30-mg/g group. Furthermore, UACR was divided into five groups: the <20%, 20%-39%, 40%-59%, 60%-79%, and ≥80% groups, according to the quintile division of participants within the normal range. Propensity score matching was used to reduce bias, and multiple logistic regression models were conducted to examine the association between UACR and HTN, T2DM, HTN with T2DM, dyslipidemia, and CVDs.

Results

Multivariable regression analysis revealed that UACR, even within the normal range, is significantly associated with HTN, T2DM, HTN with T2DM, dyslipidemia, and CVDs, and the association between UACR and HTN with T2DM was the most significant in model 3 even after adjusting for confounding factors (HTN: OR = 1.56 (95% CI = 1.45-1.68), p < 0.0001; T2DM: OR = 1.78 (95% CI = 1.60-1.97), p < 0.0001; HTN with T2DM: OR = 1.76 (95% CI = 1.59-1.95), p < 0.0001; dyslipidemia: OR = 1.08 (95% CI = 1.01-1.14), p = 0.0146; CVDs: OR = 1.12 (95% CI = 1.00-1.25), p = 0.0475). In the stratified analysis, high normal UACR was significantly associated with HTN, T2DM, HTN with T2DM, and dyslipidemia in subgroups.

Conclusions

In summary, we observe a higher prevalence of HTN, T2DM, HTN with T2DM, dyslipidemia, and CVDs in abnormal UACR and reveal a significant association of UACR, even within the normal range, with HTN, T2DM, HTN with T2DM, dyslipidemia, and CVDs.

Visceral adiposity index is closely associated with urinary albumin-creatinine ratio in the Chinese population with prediabetes

AIMS

Visceral obesity is a major health issue and is a risk factor for an atherogenic state. Visceral obesity has been reported to be a crucial link between albuminuria and cardiovascular diseases (CVD). This study attempted to explore the association between visceral obesity and albuminuria in prediabetic individuals.

METHODS

This cross-sectional study included 24871 prediabetic participants over 40 years of age from seven centres across China (REACTION study). The visceral adiposity index (VAI) was determined based on the measurements of anthropometric indices and lipid parameters. Increased albuminuria was defined as a urinary albumin-creatinine ratio (UACR) ≥30 mg/g, indicating kidney damage. Propensity score matching was used to reduce bias, and a multiple logistic regression model was performed to evaluate the association between visceral obesity and albuminuria in the population with prediabetes.

RESULTS

Participants with increased UACR exhibited increased VAI, age, blood pressure, triglycerides, poor glycaemic control, CVD events, and decreased estimated glomerular filtration rate (eGFR). Multiple logistic regression analysis demonstrated that VAI quartiles were positively associated with an increased risk of albuminuria (Q2: odds rate [OR]: 1.10, 95% confidence intervals [CI] 0.96-1.25; Q3: OR: 1.16, 95% CI 1.01-1.32; Q4: OR: 1.26, 95% CI 1.10-1.44, p for trend = 0.001). Stratified analysis revealed that the association of VAI level with increased albuminuria risk also occurred in people who were young, women, overweight or obese, with poor control of blood pressure, and eGFR ≥90 ml/min per 1.73 m² .

CONCLUSIONS

Visceral obesity assessed by VAI is significantly associated with increased UACR in a Chinese population with prediabetes.

[Preparation of the dialysis patient with type 1 diabetes mellitus for kidney transplantation]

Kidney transplantation is unique method of renal replacement therapy, allowing to improve quality and duration of life for patients with diabetes mellitus type 1 (DM1) and end-stage renal disease (ESRD) on dialysis therapy. Recently using of innovation technologies for diabetes management and modern immunosuppression enable achieving better results of posttransplant rehabilitation for patients with DM1, especially if kidney transplantation is performed early after initiation of dialysis. Detailed examination of patient with DM1 before potential kidney transplantation is very important to reduce of early and late postoperative complications. Kidney transplantation preparation includes effective glycemic control, adequate dialysis therapy, treatment of diabetes and ESRD complications and concomitant conditions, especially cardiovascular diseases, accounting for kidney transplantation perspective. Furthermore, diagnostics and treatment of any infectious process, timely vaccination, cancer screening are basic approaches of kidney transplantation preparation program, providing the best survival rate of kidney graft and patient.

Skeletal Muscle Reflex-Induced Sympathetic Dysregulation and Sensitization of Muscle Afferents in Type 1 Diabetic Rats

The blood pressure response to exercise is exaggerated in the type 1 diabetes mellitus (T1DM). An overactive exercise pressor reflex (EPR) contributes to the potentiated pressor response. However, the mechanism(s) underlying this abnormal EPR activity remains unclear. This study tested the hypothesis that the heightened blood pressure response to exercise in T1DM is mediated by EPR-induced sympathetic overactivity. Additionally, the study examined whether the single muscle afferents are sensitized by PKC (protein kinase C) activation in this disease. Sprague-Dawley rats were intraperitoneally administered either 50 mg/kg streptozotocin (T1DM) or saline (control). At 1 to 3 weeks after administration, renal sympathetic nerve activity and mean arterial pressure responses to activation of the EPR, mechanoreflex, and metaboreflex were measured in decerebrate animals. Action potential responses to mechanical and chemical stimulation were determined in group IV afferents with pPKCα (phosphorylated-PKCα) levels assessed in dorsal root ganglia. Compared with control, EPR (58±18 versus 96±33%; P<0.05), mechanoreflex (21±13 versus 51±20%; P<0.05), and metaboreflex (40±20 versus 88±39%; P<0.01) activation in T1DM rats evoked significant increases in renal sympathetic nerve activity as well as mean arterial pressure. The response of group IV afferents to mechanical (18±24 versus 61±45 spikes; P<0.01) and chemical (0.3±0.4 versus 1.6±0.8 Hz; P<0.01) stimuli were significantly greater in T1DM than control. T1DM rats showed markedly increased pPKCα levels in dorsal root ganglia compared with control. These data suggest that in T1DM, abnormally muscle reflex-evoked increases in sympathetic activity mediate exaggerations in blood pressure. Further, sensitization of muscle afferents, potentially via PKC activation, may contribute to this abnormal circulatory responsiveness.

Retinal microvascular findings and risk of incident peripheral artery disease: An analysis from the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND AND AIMS

Lower-extremity peripheral artery disease (PAD) is usually considered large artery disease. Interestingly, retinal microvascular findings were shown to predict PAD progression in diabetes. However, it is unknown whether retinal microvascular parameters are associated with incident PAD and its severe form, critical limb ischemia (CLI), in a community-based cohort.

METHODS

Among 9371 ARIC participants (aged 49-72 years) free of a history of PAD, we quantified the associations of several retinal measures by retinal photography during the period 1993-1995 with PAD risk using Cox models. Incident PAD was defined as the first hospitalization with PAD diagnosis or leg revascularization (considered CLI if an additional diagnosis of ulcer, gangrene, or amputation).

RESULTS

During a median follow-up of 18.8 years, 303 participants developed PAD (including 91 CLI cases). Although generalized retinal arteriolar narrowing was not associated with PAD, most measures of retinopathy demonstrated strong associations with PAD beyond potential confounders including diabetes, with adjusted hazard ratios (HR) of 3.26 (95% CI 2.18-4.90) for blot-shaped hemorrhages, 3.11 (1.83-5.29) for hard exudates, and 2.18 (1.62-2.95) for any retinopathy. Adjusted HRs were significantly greater for CLI (ranging from 3.2 to 5.9) than for PAD (all p-values <0.05). Retinopathy measures showed particularly strong associations in participants with diabetes (p-value for interaction [vs. those without diabetes] <0.001).

CONCLUSIONS

Several retinopathy measures were strongly associated with PAD, especially with CLI and in diabetes. Our results support the contribution of microvascular abnormalities to the development and progression of PAD and would have implications on its preventive and therapeutic approaches.

In experimental peripheral arterial disease, type 2 diabetes alters post-ischemic gene expression

Peripheral arterial disease is characterized by impaired blood flow to tissues outside the heart due to atherosclerosis and it most frequently occurs in the lower extremities. Type 2 diabetes (T2D) is a well-known risk factor that accelerate the course and contributes to poor clinical outcomes of PAD. While there is some evidence that T2D is associated with altered expression of genes involved in regulating PAD severity, our knowledge about the specific genes and pathways involved remains incomplete.

We induced experimental PAD or hind limb ischemia in T2D and non-diabetic mice and subjected the ischemic gastrocnemius muscle tissues to genome-wide mRNA transcriptome analysis. We subsequently performed pathway analysis on the top 500 genes that showed the most significant expression differences between the ischemic diabetic and ischemic non-diabetic muscle tissues. Pathway analysis of the differentially expressed genes identified pathways involved in essential biological processes such as “metabolic pathways,” “phagosomes,” “lysosomes,” and “regulation of actin cytoskeleton”. Overall, our data provides the opportunity to test hypotheses on the potential role of the altered genes/molecular pathways in poor PAD outcomes in diabetes.

Ankle Brachial Pressure Index: An update for the vascular specialist and general practitioner

Objectives

Ankle brachial pressure index (ABPI) is an invaluable tool for assessing the severity of peripheral arterial disease. In addition, it can be used as an independent marker of cardiovascular risk, with a predictive ability similar to the Framingham criteria. Identification of an abnormal ABPI should therefore trigger aggressive cardiac risk factor modulation for a patient. Unfortunately, the significance of abnormal ABPIs is poorly understood within the general medical community. This is compounded by the influence of various comorbidities on accurate measurement of ABPI, potentially leading to a wide variability in readings that need to be considered before interpretation in these patient populations. We aim to address these issues by revealing several common misunderstandings and pitfalls in ABPI measurement, describing accurate methodology, and highlighting patient cohorts in whom additional or alternative approaches may be required.

Methods

We present a narrative review of the role of ABPI in both the community and hospital setting. We have performed a literature review, exploring the validity and reproducibility of methodology for obtaining ABPI, alongside the utility of ABPI in different clinical scenarios.

Results

The measurement of ABPI is often performed incorrectly. Common pitfalls include inadequate patient preparation, failure to obtain the blood pressure from the correct lower limb artery in patients with tibial disease, failure to account for differences in brachial blood pressure between the arms, inappropriately chosen equipment and patient factors such as highly calcified arteries. Standardisation of methodology greatly improves reliability of the test. Exercise ABPI can identify significant peripheral arterial disease in patients with normal resting ABPI. In addition to its role in peripheral arterial disease, ABPI measurement has a role in assessing venous ulcers, entrapment syndromes and injured extremities; conversely, it has a more limited utility in the diabetic population.

Conclusions

A thorough understanding of the correct technique and associated limitations of ABPI measurement is essential in accurately generating and interpreting the data it provides. With this knowledge, the ABPI is an invaluable tool to help manage patients with peripheral arterial disease. Perhaps more importantly, ABPI can be used to identify and risk stratify patients with asymptomatic peripheral arterial disease, itself a major indicator of significant underlying cardiovascular disease. With the emergence of best medical therapy, targeted pharmacotherapy and lifestyle changes can reduce the risk of major cardiovascular events in high-risk patients by approximately 30%, particularly in diabetic patients. Therefore, the utility of ABPI transgresses vascular surgery, with an essential role in general practice and public health.

Vascular disease in the lower limb in type 1 diabetes

This review considers peripheral arterial disease (PAD) in the diabetic ischaemic lower limb including both macrovascular and microvascular aspects. The presentation of PAD is probably not significantly different in type 1 compared with type 2 diabetes. PAD in diabetic patients is diffuse and located distally being most severe in the crural and also the foot arteries. It is associated with arterial calcification and occlusion of the arteries rather than stenosis. Compared with the nondiabetic patient, PAD develops at a younger age, and women are equally affected as men. It is not known whether the presentation of ischaemic lower limb disease in diabetes can be explained by one disease, namely, atherosclerosis, which has particular features peculiar to diabetes such as distal arterial involvement, or by the occurrence of two separate diseases: first, classical atherosclerosis and, second, a diabetic macroangiopathy, a term for nonatherosclerotic arterial disease in diabetes that is characterized by medial arterial calcification. Furthermore, there is controversy with regard to the significance of structural changes in the microcirculation of the diabetic foot.

CaMKII in Vascular Signalling: "Friend or Foe"?

Signalling mechanisms within and between cells of the vasculature enable function and maintain homeostasis. However, a number of these mechanisms also contribute to the pathophysiology of vascular disease states. The multifunctional signalling molecule calcium/calmodulin-dependent kinase II (CaMKII) has been shown to have critical functional effects in many tissue types. For example, CaMKII is known to have a dual role in cardiac physiology and pathology. The function of CaMKII within the vasculature is incompletely understood, but emerging evidence points to potential physiological and pathological roles. This review discusses the evidence for CaMKII signalling within the vasculature, with the aim to better understand both positive and potentially deleterious effects of CaMKII activation in vascular tissue.

The comparative efficacy of angiosome-directed and indirect revascularisation strategies to aid healing of chronic foot wounds in patients with co-morbid diabetes mellitus and critical limb ischaemia: a literature review

BACKGROUND

Ischaemic ulcerations have been reported to persist and/or deteriorate despite technically successful revascularisations; a higher incidence of which affects patients with diabetes and critical limb ischaemia. In the context of wound healing, it is unclear if applications of the angiosome concept in 'direct revascularisation' (DR) would be able to aid the healing of chronic foot ulcerations better than the current 'best vessel' or 'indirect revascularisation' (IR) strategy in patients with co-morbid diabetes and critical limb ischaemia.

METHODS

A literature search was conducted in eight electronic databases, namely AMED, CINAHL, The Cochrane Library, ProQuest Health & Medicine Complete, ProQuest Nursing & Allied Health Source, PubMed, ScienceDirect and TRIP database. Articles were initially screened against a pre-established inclusion and exclusion criteria to determine eligibility and subsequently appraised using the Newcastle-Ottawa Scale.

RESULTS

Five retrospective studies of varying methodological quality were eligible for inclusion in this review. Critical analysis of an aggregated population (n = 280) from methodologically stronger studies indicates better wound healing outcomes in subjects who had undergone DR as compared to IR (p < 0.001; p = 0.04). DR also appears to result in a nearly twofold increase in probability of wound healing within 12 months (hazard ratio, 1.97; 95% CI, 1.34-2.90). This suggests that achieving direct arterial perfusion to the site of ulceration may be important for the healing of chronic diabetic foot ulcerations.

CONCLUSION

Incorporating an angiosome-directed approach in the lower limb revascularisation strategy could be a very useful adjunct to a solely indirect approach, which could increase the likelihood of wound healing. With the limited data currently available, findings appear promising and merit from further investigation. Additional research to form a solid evidence base for this revised strategy in patients with co-morbid diabetes and critical limb ischaemia is warranted.

The receptor for advanced glycation end products and risk of peripheral arterial disease, amputation or death in type 2 diabetes: a population-based cohort study

Background

Patients with type 2 diabetes have a high risk for early and extensive development of peripheral arterial disease (PAD) and this excess risk is not explained by increased burden of traditional atherosclerotic risk factors. Activation of the receptor for advanced glycation end products (RAGE) could be one additional mechanism for accelerated PAD and increased risk for amputation and death. We investigated the association between RAGE plasma components and the risk for PAD, amputation and death in patients with type 2 diabetes. We also estimated the rate of amputation-free survival and survival without PAD.

Methods

We investigated if plasma levels of carboxymethyl-lysine, S100A12 and endosecretory RAGE (esRAGE) were associated with two endpoints: survival without development of PAD and survival without amputation in a 12 years prospective population-based cohort of 146 patients with type 2 diabetes, free from PAD at inclusion. Influence of baseline plasma levels of RAGE ligands (individually and combined by a RAGE-score) were evaluated for both endpoints in the Cox-regression analysis.

Results

106 patients survived without amputation and 93 survived without signs of PAD during follow up. Higher levels of S100A12 and RAGE-score were associated with increased risk for amputation or death, hazard ratios (HR) 1.29; 95% confidence interval (CI) [1.04, 1.59] and 1.79; 95% CI [1.07, 2.99] and with increased risk for PAD or death, HR 1.22; 95% CI [1.00, 1.49] and 1.56; [1.00, 2.44] after adjustment for age and sex. The effect was decreased after adjustment for Framingham cardiovascular disease score: risk for amputation or death, HR 1.17; 95% CI [0.94, 1.46] and 1.54; [0.95, 2.49], and risk for PAD or death, HR 1.12; 95% CI [0.91, 1.38] and 1.38; [0.91, 2.11] for S100A12 and RAGE-score respectively. The incidence for amputation or death was 2.8 per 100 person-years; 95% CI [2.0, 3.7] and the incidence rate for PAD or death was 3.6 per 100 person-years; 95% CI [2.7, 4.8].

Conclusion

Higher plasma levels of S100A12 and the combined effect (RAGE-score) of esRAGE, carboxymethyl-lysine and S100A12 seem to be associated with shorter PAD- and amputation-free survival in patients with type 2 diabetes. This may indicate a role for S100A12 in PAD by activation of the RAGE system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0257-5) contains supplementary material, which is available to authorized users.

Use and utility of ankle brachial index in patients with diabetes

Ankle brachial index (ABI) is a simple method to screen peripheral arterial disease (PAD) and to evaluate cardiovascular (CV) prognosis in the general population. Measuring it requires a hand-held Doppler probe but it can be done also with an automatic device. ABI is an effective tool for clinical practice or clinical studies. However, in diabetic patients, it has some specific caveats. Sensitivity of the standard threshold of 0.9 appears to be lower in diabetic patients with complications. Moreover, highly frequent arterial medial calcifications in diabetes increase ABI. It has been demonstrated that measurements >1.3 are well correlated with both an increased prevalence of PAD and CV risk. Therefore, ABI thresholds of less than 0.9 and more than 1.3 are highly suspicious for PAD and high CV risk in diabetic patients. However, when there is concomitant clinical peripheral neuropathy or high risk of arterial calcification, the efficiency of ABI seems to be limited. In this case, other methods should be applied, toe pressure, in particular. Thus, the ABI could be used in patients with diabetes, but values should be interpreted with precision, according to the clinical situation.

Peripheral arterial disease in diabetes--a review

Diabetic patients are at high risk for peripheral arterial disease (PAD) characterized by symptoms of intermittent claudication or critical limb ischaemia. Given the inconsistencies of clinical findings in the diagnosis of PAD in the diabetic patient, measurement of ankle-brachial pressure index (ABI) has emerged as the relatively simple, non-invasive and inexpensive diagnostic tool of choice. An ABI < 0.9 is not only diagnostic of PAD even in the asymptomatic patient, but is also an independent marker of increased morbidity and mortality from cardiovascular diseases. With better understanding of the process of atherosclerosis, avenues for treatment have increased. Modification of lifestyle and effective management of the established risk factors such as smoking, dyslipidaemia, hyperglycaemia and hypertension retard the progression of the disease and reduce cardiovascular events in these patients. Newer risk factors such as insulin resistance, hyperfibrinogenaemia, hyperhomocysteinaemia and low-grade inflammation have been identified, but the advantages of modifying them in patients with PAD are yet to be proven. Therapeutic angiogenesis, on the other hand, represents a promising therapeutic adjunct in the management of PAD in these patients. Outcomes after revascularization procedures, such as percutaneous transluminal angioplasty and surgical bypasses in diabetic patients, are poorer, with increased perioperative morbidity and mortality compared with that in non-diabetic patients. Amputation rates are higher due to the distal nature of the disease. Efforts towards increasing awareness and intensive treatment of the risk factors will help to reduce morbidity and mortality in diabetic patients with PAD.

The role of ankle-brachial index as a screening test for coronary artery disease in the Hispanic population

OBJECTIVES

This study evaluated the role of ankle-brachial index (ABI) as an effective screening test of coronary artery disease (CAD) in the Hispanic population.

METHODS

This was an observational cross-sectional study, based on a retrospective review of the medical management of the study patients using already available data. The study comprised 155 patients, aged 50 to 70 years with metabolic syndrome but no known CAD, presenting in El Paso, Texas between February 2004 and November 2006. An ABI test had been performed on all the patients in this study. Also, myocardial nuclear perfusion imaging using single photon emission computed tomography and electrocardiogram gating tests had been performed on these patients, because they all had multiple traditional risk factors for CAD.

RESULTS

Sensitivity of low ABI in screening for CAD was 82.61%, while the specificity was 77.27%.

CONCLUSION

ABI is an effective and cost-efficient screening test for CAD.

Metabolic syndrome and incident end-stage peripheral vascular disease: a 14-year follow-up study in elderly Finns

OBJECTIVE

We investigated the relationship of the metabolic syndrome and its single components, defined by four different criteria, with peripheral vascular disease (PVD) in a prospective population-based study.

RESEARCH DESIGN AND METHODS

The metabolic syndrome was defined according to the World Health Organization (WHO), the National Cholesterol Education Program (NCEP), the International Diabetes Federation (IDF), and the American Heart Association (updated NCEP) criteria. We investigated the relationship of the metabolic syndrome defined by the aforementioned four criteria with PVD (revacularization and amputation) by Cox regression analyses in a Finnish population of 1,212 subjects, aged 65-74 years, with and without diabetes during a 14-year follow-up.

RESULTS

The metabolic syndrome defined by the WHO, NCEP, and updated NCEP criteria was associated with a statistically significant risk for incident PVD (n = 57) with adjustment for all confounding variables except for prevalent diabetes (hazard ratios [HRs] from 1.91 to 2.62). After adjustment for prevalent diabetes or after the exclusion of subjects with prevalent diabetes, there was no association between the metabolic syndrome by any criteria and incident PVD. Of the single components of the metabolic syndrome, elevated fasting glucose by the WHO and NCEP criteria (HR 2.35) and microalbuminuria by the WHO definition (2.56) predicted PVD in multivariable models (prevalent diabetes included).

CONCLUSIONS

The metabolic syndrome defined by the WHO, NCEP, and updated NCEP criteria predicted incident end-stage PVD in elderly Finns but only when not adjusted for diabetes status. Two of the single components of the metabolic syndrome, elevated fasting plasma glucose and microalbuminuria, predicted PVD. We conclude that the metabolic syndrome predicts PVD but not above and beyond the risk associated with diabetes and microalbuminuria.

Non-traditional cardiovascular risk factors contribute to peripheral arterial disease in patients with type 2 diabetes

OBJECTIVE

This study evaluated the prevalence of peripheral arterial disease (PAD) in type 2 diabetes and its association with traditional and non-traditional cardiovascular (CV) risk factors.

SUBJECTS AND METHODS

In 1610 type 2 diabetics PAD was defined as ankle-brachial pressure index (ABPI)<0.9.

RESULTS

PAD prevalence was 17%, increased with age, diabetes duration, HbA 1c levels, previous CV events. There were no significant differences in the prevalence of traditional CV risk factors between patients with and without PAD. PAD patients had higher levels of fibrinogen (10.88+/-2.32 versus 10.2+/-2.23micromol/L; p<0.0001), uric acid (327.1+/-89.2 versus 315.2+/-83.3micromol/L, p<0.01), pulse pressure (70+/-18 versus 60+/-16mm Hg, p<0.0001), higher rate of microalbuminuria (21.3% versus 13.7%; p<0.05) and lower glomerular filtration rate (GFR, 80.7+/-24 versus 89.9+/-22 ml/min/1.73 m2; p<0.001) than those without. In age-gender-adjusted analysis, smoking (OR 1.5; CI: 1.07-2.2), HbA 1c (OR 1.45; CI: 1.07-2.08), high pulse pressure (OR 2.81; CI: 1.63-4.82), reduced GFR (OR 2.16; CI: 1.4-3.3), microalbuminuria (OR 1.62; CI: 1.11-2.36), high fibrinogen levels (OR 2.03; CI: 1.34-3.07) were associated with PAD. In multivariate analysis age, male sex, smoking, high pulse pressure, low GFR, high fibrinogen levels, previous CV events were independent risk factors for PAD.

CONCLUSIONS

PAD prevalence is high in Type 2 diabetic patients. Non-traditional cardiovascular risk factors may be involved in the development of this complication.

Ankle brachial pressure index usefulness as predictor factor for coronary heart disease in diabetic patients

Ankle brachial pressure index (ABPI) is a non-invasive marker of atherosclerosis, helpful to identify subjects at high-risk for coronary heart disease (CHD) among large populations with cardiovascular disease (CVD) risk factors. The diagnostic role of ABPI has been also recognized in patients with diabetes. In the present study, the role of an ABPI score < 0.90 in predicting CHD has been evaluated in a large series of patients with Type 2 diabetes mellitus and compared to other known CVD risk factors. Nine hundred and sixty-nine (mean age was 66.1 yr) consecutive patients with Type 2 diabetes mellitus were evaluated. The patients were followed-up for 18.3+/-5.2 months (range 12- 24) and all events of CHD, defined as myocardial infarction, unstable and resting angina or coronary atherosclerosis at the instrumental investigation (at the coronary angiography and/or perfusion stress testing) were recorded. A rate of 17.5% of CHD events were recorded in diabetic population during the follow-up period. The relative risk of CHD was significantly increased for male patients [odds ratio (OR): 1.6; 95% confidence interval (CI): 1.1-2.2], patients with age > or = 66 yr (OR: 1.8; 95% CI: 1.3-2.5), body mass index (BMI) > 30 (OR: 1.5; 95% CI: 1.1-2.1), waist circumference > 88 cm for females and 102 cm for males (OR: 1.5; 95% CI: 1.0-2.1), proteinuria > or = 30 microg per min (OR: 1.6; 95% CI: 1.1-2.3), LDL-cholesterol > or = 100 mg/dl (OR: 2.1; 95% CI: 1.5-3.0), glycated hemoglobin > 7% (OR: 1.6; 95% CI: 1.1-2.3), insulin therapy (OR: 1.9; 95% CI: 1.3-2.9), and ABPI < 0.90 (OR: 3.7; 95% CI: 2.2- 6.2). BMI was higher in patients with ABPI < 0.90 than in those with ABPI > or = 0.90 (p<0.05). At the multivariate analysis, ABPI < 0.90 was the best factor independently associated with CHD (p<0.001). APBI < 0.90 is strongly associated to CHD in Type 2 diabetic patients. We recommend to use ABPI in diabetic patients and to carefully monitor diabetic subjects with an ABPI lower than 0.90.

Microalbuminuria and cardiovascular disease

To reduce the burden of cardiovascular disease (CVD), management strategies are increasingly focusing on preventive measures following early detection of markers of atherosclerosis. This review focuses on microalbuminuria, which is gaining recognition as a simple marker of an atherogenic milieu. Prospective and epidemiologic studies have found that microalbuminuria is predictive, independently of traditional risk factors, of all-cause and cardiovascular mortality and CVD events within groups of patients with diabetes or hypertension, and in the general population. The pathophysiologic mechanism underlying the association between albumin excretion and CVD is not fully defined. One hypothesis is that microalbuminuria may be a marker of CVD risk because it reflects subclinical vascular damage in the kidneys and other vascular beds. It may also signify systemic endothelial dysfunction that predisposes to future cardiovascular events. Based on this theory, periodic screening for microalbuminuria could allow early identification of vascular disease and help stratify overall cardiovascular risk, especially in patients with risk factors such as hypertension or diabetes. A positive test for urinary albumin excretion could signify the need for an intensive multifactorial intervention strategy, including behavior modification and targeted pharmacotherapy, aimed at preventing further renal deterioration and improving the overall CVD risk factor profile. Data from intervention studies suggest that treatment with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, statins, and/or strict glycemic control (in diabetics) offer significant reductions in cardiovascular and/or renal morbidity in patients with albuminuria. Use of this (old) marker may allow improved use of medications and strategies for secondary prevention.

Sensitivity and specificity of the ankle-brachial index to predict future cardiovascular outcomes: a systematic review

OBJECTIVE

The ankle-brachial index is the ratio of the ankle and the brachial systolic blood pressure and is used to assess individuals with peripheral arterial disease. An ankle-brachial index <0.90 suggests the presence of peripheral arterial disease and is a marker of cardiovascular risk. The objective of this review is to determine the sensitivity and specificity of an ankle-brachial index <0.90 to predict future cardiovascular events, including coronary heart disease, stroke, and death.

METHODS AND RESULTS

We conducted a systematic review of the literature and included studies that used an ankle-brachial index cutoff between 0.80 and 0.90 to classify patients with or without peripheral arterial disease, followed patients prospectively, and recorded cardiovascular outcomes (ie, myocardial infarction, stroke, or mortality). Data were combined using a random-effects model meta-analysis to determine the sensitivity, specificity, relative risks, and likelihood ratios of a low ankle-brachial index to predict future cardiovascular disease. A total of 22 studies were identified, 13 were excluded, and 9 studies were included in the meta-analysis. The sensitivity and specificity of a low ankle-brachial index to predict incident coronary heart diseases were 16.5% and 92.7%, for incident stroke were 16.0% and 92.2%, and for cardiovascular mortality were 41.0% and 87.9%, respectively. The corresponding positive likelihood ratios were 2.53 (95% CI, 1.45 to 4.40) for coronary heart disease, 2.45 (95% CI, 1.76 to 3.41) for stroke, and 5.61 (95% CI, 3.45 to 9.13) for cardiovascular death.

CONCLUSIONS

The specificity of a low ankle-brachial index to predict future cardiovascular outcomes is high, but its sensitivity is low. The ankle-brachial index should become part of the vascular risk assessment among selected individuals.