Lipid levels and peripheral vascular disease in diabetic and non-diabetic subjects

Association of apolipoprotein levels with peripheral arterial disease: a meta-analysis of literature studies

AIMS

Lower limb peripheral artery disease (PAD) is a leading cause of atherosclerotic cardiovascular disease (ASCVD). Discordant data are available on the association between apolipoprotein and PAD. We performed a meta-analyses on the association between apolipoprotein (apo)B, apoA-I, and apoB/apoA-I ratio with PAD.

METHODS AND RESULTS

PubMed, Web of Science, Scopus databases were systematically searched. Studies providing data about apoB, apoA-I, apoB/apoA-I ratio in PAD subjects and non-PAD controls were included. Differences between PAD and non-PAD subjects were expressed as mean difference (MD) with pertinent 95% confidence intervals (95%CI). Twenty-two studies were included. Peripheral artery disease subjects showed higher apoB (MD: 12.5 mg/dL, 95%CI: 2.14, 22.87) and lower apoA-I levels (MD: -7.11 mg/dL, 95%CI: -11.94, -2.28) than non-PAD controls. Accordingly, ApoB/ApoA-I ratio resulted higher in PAD subjects than non-PAD controls (MD: 0.11, 95% CI: 0.00, 0.21). Non-HDL-C showed a direct association with the difference in apoB (z-value: 4.72, P < 0.001) and an inverse association with the difference of apoA-I (z-value: -2.43, P = 0.015) between PAD subjects and non-PAD controls. An increasing BMI was associated with an increasing difference in apoA-I values between PAD subjects and non-PAD controls (z-value: 1.98, P = 0.047).

CONCLUSIONS

Our meta-analysis suggests that PAD subjects exhibit increased apoB and reduced apoA-I levels, accompanied by an increased apoB/apoA-I ratio as compared with non-PAD controls.

Factors associated with diabetic polyneuropathy-related sensory symptoms and signs in patients with polyneuropathy: A cross-sectional Japanese study (JDDM 52) using a non-linear model

AIMS/INTRODUCTION

To assess the prevalence of diabetic polyneuropathy (DPN)-related sensory symptoms/signs and associated factors in patients with polyneuropathy, considering non-linear effects for numerical variables.

MATERIALS AND METHODS

A cross-sectional survey of patients with type 2 diabetes mellitus from 17 primary care clinics across Japan was carried out. DPN and DPN-related sensory symptoms/signs were diagnosed according to the Diabetic Neuropathy Study Group in Japan criteria.

RESULTS

Of the 9,914 patients with type 2 diabetes mellitus in this study, 2,745 had DPN and 1,689 had DPN-related sensory symptoms/signs (61.5% of patients with DPN). There were significant correlations between DPN-related sensory symptoms/signs and smoking status (odds ratio 2.04 for current and 1.64 for former; P < 0.001 and P = 0.002, respectively), sex (odds ratio 0.56 for male/female; P < 0.001) and alcohol consumption (odds ratio 2.02 for former/never; P = 0.004). Based on the non-linear logistic regression model, significant correlations were observed between the presence of DPN-related sensory symptoms/signs and higher systolic blood pressure (SBP), longer diabetes duration, and decreasing age. The logarithm of odds for SBP increased until reaching approximately 130 mmHg, then it plateaued.

CONCLUSIONS

Some modifiable factors assessed in the large survey database might be associated with DPN-related sensory symptoms/signs, namely smoking, alcohol consumption and SBP. Maintaining SBP <130 mmHg was associated with lower odds of DPN-related sensory symptoms/signs in patients with DPN.

Lipoprotein Particle Profiles, Standard Lipids, and Peripheral Artery Disease Incidence

BACKGROUND

Despite strong and consistent prospective associations of elevated low-density lipoprotein (LDL) cholesterol concentration with incident coronary and cerebrovascular disease, data for incident peripheral artery disease (PAD) are less robust. Atherogenic dyslipidemia characterized by increased small LDL particle (LDL-P) concentration, rather than total LDL cholesterol content, along with elevated triglyceride-rich lipoproteins and low high-density lipoprotein (HDL) cholesterol (HDL-C), may be the primary lipid driver of PAD risk.

METHODS

The study population was a prospective cohort study of 27 888 women ≥45 years old free of cardiovascular disease at baseline and followed for a median of 15.1 years. We tested whether standard lipid concentrations, as well as nuclear magnetic resonance spectroscopy-derived lipoprotein measures, were associated with incident symptomatic PAD (n=110) defined as claudication and/or revascularization.

RESULTS

In age-adjusted analyses, while LDL cholesterol was not associated with incident PAD, we found significant associations for increased total and small LDL-P concentrations, triglycerides, and concentrations of very LDL (VLDL) particle (VLDL-P) subclasses, increased total cholesterol (TC):HDL-C, low HDL-C, and low HDL particle (HDL-P) concentration (all P for extreme tertile comparisons <0.05). Findings persisted in multivariable-adjusted models comparing extreme tertiles for elevated total LDL-P (adjusted hazard ratio [HR_adj] 2.03; 95% CI, 1.14-3.59), small LDL-P (HR_adj 2.17; 95% CI, 1.10-4.27), very large VLDL-P (HR_adj 1.68; 95% CI, 1.06-2.66), medium VLDL-P (HR_adj 1.98; 95% CI, 1.15-3.41), and TC:HDL-C (HR_adj, 3.11; 95% CI, 1.67-5.81). HDL was inversely associated with risk; HR_adj for extreme tertiles of HDL-C and HDL-P concentration were 0.30 ( P trend < 0.0001) and 0.29 ( P trend < 0.0001), respectively. These components of atherogenic dyslipidemia, including small LDL-P, medium and very large VLDL-P, TC:HDL-C, HDL-C, and HDL-P, were more strongly associated with incident PAD than incident coronary and cerebrovascular disease. Finally, the addition of LDL-P and HDL-P concentration to TC:HDL-C measures identified women at heightened PAD risk.

CONCLUSIONS

In this prospective study, nuclear magnetic resonance-derived measures of LDL-P, but not LDL cholesterol, were associated with incident PAD. Other features of atherogenic dyslipidemia, including elevations in TC:HDL-C, elevations in triglyceride-rich lipoproteins, and low standard and nuclear magnetic resonance-derived measures of HDL, were significant risk determinants. These data help clarify prior inconsistencies and may elucidate a unique lipoprotein signature for PAD compared to coronary and cerebrovascular disease.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov/ . Unique Identifier: NCT00000479.

Low-density-lipoprotein particle size predicts a poor outcome in patients with atherothrombotic stroke

BACKGROUND AND PURPOSE

Low-density lipoprotein (LDL) particle size is considered to be one of the more important cardiovascular risk factors, and small LDL particles are known to have atherogenic potential. The aim of this study was to determine whether LDL particle size is associated with stroke severity and functional outcome in patients with atherothrombotic stroke.

METHODS

Between January 2009 and May 2011, 248 patients with first-episode cerebral infarction who were admitted to our hospital within 7 days after symptom onset were prospectively enrolled. LDL particle size was measured using the nondenaturing polyacrylamide gradient gel electrophoresis assay. Stroke severity was assessed by applying the National Institutes of Health Stroke Scale (NIHSS) at admission. Functional outcome was investigated at 3 months after the index stroke using the modified Rankin Scale (mRS), and poor functional outcome was defined as an mRS score of ≥3.

RESULTS

The LDL particle size in the 248 patients was 25.9±0.9 nm (mean±SD). LDL particle size was inversely correlated with the degree of cerebral artery stenosis (p=0.010). Multinomial multivariate logistic analysis revealed that after adjustment for age, sex, and variables with p<0.1 in univariate analysis, LDL particle size was independently and inversely associated with stroke severity (NIHSS score ≥5; reference, NIHSS score 0-2; odds ratio=0.38, p=0.028) and poor functional outcome (odds ratio=0.44, p=0.038).

CONCLUSIONS

The results of this study demonstrate that small LDL particles are independently correlated with stroke outcomes. LDL particle size is thus a potential biomarker for the prognosis of atherothrombotic stroke.

Peripheral arterial disease, type 2 diabetes and postprandial lipidaemia: Is there a link?

Peripheral arterial disease, manifested as intermittent claudication or critical ischaemia, or identified by an ankle/brachial index < 0.9, is present in at least one in every four patients with type 2 diabetes mellitus. Several reasons exist for peripheral arterial disease in diabetes. In addition to hyperglycaemia, smoking and hypertension, the dyslipidaemia that accompanies type 2 diabetes and is characterised by increased triglyceride levels and reduced high-density lipoprotein cholesterol concentrations also seems to contribute to this association. Recent years have witnessed an increased interest in postprandial lipidaemia, as a result of various prospective studies showing that non-fasting triglycerides predict the onset of arteriosclerotic cardiovascular disease better than fasting measurements do. Additionally, the use of certain specific postprandial particle markers, such as apolipoprotein B-48, makes it easier and more simple to approach the postprandial phenomenon. Despite this, only a few studies have evaluated the role of postprandial triglycerides in the development of peripheral arterial disease and type 2 diabetes. The purpose of this review is to examine the epidemiology and risk factors of peripheral arterial disease in type 2 diabetes, focusing on the role of postprandial triglycerides and particles.

Lipoprotein(a), inflammation, and peripheral arterial disease in a community-based sample of older men and women (the InCHIANTI study)

Lipoprotein(a) (Lp[a]) may represent an independent risk factor for peripheral arterial disease of the lower limbs (LL-PAD), but prospective data are scant. We estimated the association between baseline Lp(a) with prevalent and incident LL-PAD in older subjects from the InCHIANTI Study. LL-PAD, defined as an ankle-brachial index <0.90, was assessed at baseline and over a 6-year follow-up in a sample of 1,002 Italian subjects 60 to 96 years of age. Plasma Lp(a) and potential traditional and novel cardiovascular risk factors (including a score based on relevant inflammatory markers) were entered in multivariable models to assess their association with prevalent and incident LL-PAD. At baseline, Lp(a) concentration was directly related to the number of increased inflammatory markers (p <0.05). There were 125 (12.5%) prevalent cases of LL-PAD and 57 (8.3%) incident cases. After adjustment for potential confounders, participants in the highest quartile of the Lp(a) distribution (>/=32.9 mg/dl) were more likely to have LL-PAD compared to those in the lowest quartile (odds ratio [OR] 1.83, 95% confidence interval [CI] 1.01 to 3.33). The association was stronger (OR 3.80, 95% CI 1.50 to 9.61) if LL-PAD was defined by harder criteria, namely an ankle-brachial index <0.70. Compared to subjects in the lowest Lp(a) quartile, those in the highest quartile showed a somewhat increased risk of incident LL-PAD (lowest quartile 7.7%, highest quartile 10.8%), but the association was not statistically significant (OR 1.52, 95% CI 0.71 to 3.22). In conclusion, Lp(a) is an independent LL-PAD correlate in the cross-sectional evaluation, but further prospective studies in larger populations, with longer follow-up and more definite LL-PAD ranking, might be needed to establish a longitudinal association.

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 predictive role of atherogenic dyslipidemia in subjects with non-coronary atherosclerosis

BACKGROUND

Recent findings have suggested that subjects with non-coronary atherosclerosis may show elevated prevalence of atherogenic dyslipidemia, including higher triglyceride levels, reduced HDL-cholesterol concentrations and increased levels of small, dense low-density lipoproteins (LDL). These three lipid abnormalities constitute the so-called "atherogenic-lipoprotein-phenotype" (ALP) but its predictive role in these patients still remains to be established.

METHODS

We performed a 2-year follow-up study to assess clinical and biochemical predictors of cardiovascular events in 44 male patients (64+/-5 years, BMI: 27+/-3), 26 with peripheral arterial disease and 18 with abdominal aortic aneurysm. Beyond traditional cardiovascular risk factors, we measured LDL size and subclasses by gradient gel electrophoresis.

RESULTS

Clinical events were registered in the 43% of patients. At univariate analysis we found that patients with events had increased prevalence of hypertension (p=.0098), diabetes (p=.0089), family history of cardiovascular diseases (p=.0089), of elevated small, dense LDL (p=.0222) and ALP (p=.0224). At multivariate analysis (including all clinical and laboratory variables) we found the following independent predictors of events: hypertension (OR 8.9, p=.0347), diabetes (OR 9.4, p=.0270), elevated small, dense LDL (OR 6.9, p=.0488) and ALP (OR 8.7, p=.0497).

CONCLUSIONS

This is the first study that evaluated the predictive role of ALP beyond traditional cardiovascular risk factors in patients with peripheral arterial disease or abdominal aortic aneurysm. We confirmed that hypertension and diabetes are strong predictors of cardiovascular events in these subjects but ALP seems to be an independent predictor too. Yet, the therapeutical consequences of these findings need to be tested by future studies.

Atherogenic dyslipidemia and oxidative stress: a new look

Although results from in vitro studies and clinical trials demonstrate strong associations between oxidative stress and cardiovascular risk, to date still no convincing data are available to suggest that treatment with antioxidants might reduce vascular events. Oxidative modifications of low-density lipoproteins (LDL) represent an early stage of atherosclerosis, and small, dense LDL are more susceptible to oxidation than larger, more buoyant particles. Oxidized LDL are independent predictors of subclinical and clinical atherosclerosis. Recent studies suggested that novel therapeutic strategies may take into account the removal of such particles from circulation. Future research is required to explore the potential synergistic impact of markers of oxidative stress and atherogenic dyslipidemia, particularly small dense LDL, on cardiovascular risk.

Increased apoB/apoA-I Ratio is Predictive of Peripheral Arterial Disease in Initially Healthy 58-Year-old Men during 8.9 Years of Follow-up

The aim of the present study was to investigate, if increased levels of apoB/apoA-I ratios are associated with future peripheral arterial disease as measured by ankle-brachial index. Increased apoB/apoA-I levels are defined as 0.9, which has been suggested for men, and as 0.63, which has observed to be associated with plaques in the femoral artery. The study was performed in a cohort of initially clinically healthy 58-year-old men living in the city of Göteborg, Sweden. The group with an apoB/apoA-I ratio ≥0.9 had a significantly increased risk of having PAD during 8.9 years of follow-up than the group below that level (OR: 2.15 CI: 1.21 to 3.82, p < 0.01). When applying the lower apoB/apoA-I cut off, results showed that the group with a level >0.63 had more than a three-fold risk of future PAD compared to the group ≤0.63 (OR: 3.28 CI: 1.14 to 9.40, p < 0.05).

Who needs to care about small, dense low-density lipoproteins?

BACKGROUND

Increasing evidence suggest that the 'quality' rather than only the 'quantity' of low-density lipoprotein (LDL) exerts a great influence on the cardiovascular risk. Small, dense LDL seem to be an important predictor of cardiovascular events and progression of coronary artery disease (CAD) and their predominance has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III.

DISCUSSION

Some studies showed in past years that small, dense LDL are usually elevated in patients at very high cardiovascular risk, such as those with CAD and type 2 diabetes. More recently elevated levels of these particles have been found in other categories of patients at high cardiovascular risk, such as those with non-coronary forms of atherosclerosis (e.g. with carotid artery disease, aortic abdominal aneurysm and peripheral arterial disease) and metabolic diseases (with polycystic ovary syndrome and growth hormone deficiency); notably, in most of them, the predominance of small, dense LDL characterised their type of dyslipidaemia, alone or in combination with elevated triglycerides and reduced high-density lipoproteins cholesterol concentrations.

CONCLUSIONS

The therapeutical modulation of small, dense LDL have been shown to significantly reduce cardiovascular risk and weight reduction and increased physical activity may constitute first-line therapy. In addition, lipid-lowering drugs are able to favourably alter these particles and fibrates and nicotinic acid seem to be the most effective agents. Promising data are also available with the use of rosuvastatin, the latest statin introduced in the market, and ezetimibe, a cholesterol absorption inhibitor.

Atherogenic lipoprotein phenotype and LDL size and subclasses in patients with peripheral arterial disease

The type of dyslipidemia in patients with peripheral arterial disease (PAD) is still ill defined. PAD patients often show elevated triglycerides and reduced HDL-cholesterol, two lipid abnormalities usually accompanied by decreased LDL size in the "atherogenic lipoprotein phenotype" (ALP). We investigated (1) whether PAD patients have lower LDL size, (2) altered LDL subclass distribution and (3) the prevalence of ALP. We measured plasma lipids and LDL size and subclasses by gradient gel electrophoresis in 31 adults with intermittent claudication and 31 age-BMI-matched controls. Patients had higher prevalence of hypertension (p=.0132), smoking (p<.0020) and diabetes (p=.0024), with lower HDL-cholesterol (p<.0001) and increased triglycerides (p=.0057); LDL size was smaller (p<.0001), with decreased larger subclasses (LDL-I, p<.0001; LDL-IIA, p=.0068) and increased smaller particles (LDL-IIIA, p<.0001; LDL-IIIB, p=.0013; LDL-IVA, p=.0029; LDL-IVB, p<.0001). The presence of PAD was independently associated with smoking (OR 7.2, p=.0099), hypertension (OR 6.5, p=.0362), diabetes (OR 5.5, p=.0450) and elevated small, dense LDL (OR 6.7, p=.0497). The concomitant presence of high triglycerides, low HDL-cholesterol and elevated small, dense LDL in patients was 26% (versus 0% controls, p=.0024). ALP seems to characterize PAD dyslipidemia, but prospective studies are needed to test whether this lipoprotein phenotype may represent a risk factor too.

Small, dense low-density-lipoproteins and the metabolic syndrome

Small, dense low-density-lipoproteins (LDL) are associated with increased risk for cardiovascular diseases and diabetes mellitus and a reduction in LDL size has been reported in patients with coronary and non-coronary forms of atherosclerosis. LDL size has been accepted as an important predictor of cardiovascular events and progression of coronary artery disease as well as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. Small, dense LDL, with elevated triglyceride levels and low HDL-cholesterol concentrations, constitute the 'atherogenic lipoprotein phenotype (ALP)', a form of atherogenic dyslipidemia that is a feature of type 2 diabetes and the metabolic syndrome. LDL size and subclasses show specific alterations in patients with the metabolic syndrome that probably significantly increase their cardiovascular risk; however, so far it has not been recommended to incorporate LDL size measurements in treatment plans, when hypolipidemic therapies are installed. Patients with type 2 diabetes are at high cardiovascular risk and it is still on debate if the treatment goals may be identical or whether there are distinct groups with different cardiovascular risks and hence with different treatment goals. Measurements beyond traditional lipids, such as measurements on the presence of small, dense LDL in patients with the metabolic syndrome, may help to identify cardiovascular risk subgroups. In addition, it might be possible in the future to individualize hypolipidemic treatments if more than the traditional lipids are taken into account. LDL size measurement may potentially help to assess cardiovascular risk within the metabolic syndrome and adapt the treatment goals thereafter.

Clinical importance and therapeutic modulation of small dense low-density lipoprotein particles

The National Cholesterol Education Programme Adult Treatment Panel III accepted the predominance of small dense low-density lipoprotein (sdLDL) as an emerging cardiovascular disease (CVD) risk factor. Most studies suggest that measuring low-density lipoprotein (LDL) particle size, sdLDL cholesterol content and LDL particle number provides additional assessment of CVD risk. Therapeutic modulation of small LDL size, number and distribution may decrease CVD risk; however, no definitive causal relationship is established, probably due to the close association between sdLDL and triglycerides and other risk factors (e.g., high-density lipoprotein, insulin resistance and diabetes). This review addresses the formation and measurement of sdLDL, as well as the relationship between sdLDL particles and CVD. The effect of hypolipidaemic (statins, fibrates and ezetimibe) and hypoglycaemic (glitazones) agents on LDL size and distribution is also discussed.

Low-density lipoprotein size and cardiovascular prevention

Low-density lipoprotein (LDL) size appears to be an important predictor of cardiovascular events and progression of coronary artery disease, and the predominance of small, dense LDL has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. Yet, other authors have suggested that LDL subclass measurement does not add independent information to that conferred generically by LDL concentration and other standard risk factors. Therefore, the debate continues as to whether to measure LDL particle size for cardiovascular prevention and, if so, in which categories of patients. Since the therapeutic modulation of distinct LDL subspecies is of great benefit in reducing the risk of cardiovascular events, LDL size measurement should be extended as much as possible to patients at high risk of cardiovascular diseases.

Low-density lipoprotein size and cardiovascular risk assessment

A predominance of small, dense low-density lipoproteins (LDL) has been accepted as an emerging cardiovascular risk factor by the National Cholesterol Education Program Adult Treatment Panel III. LDL size seems to be an important predictor of cardiovascular events and progression of coronary heart disease and evidences suggests that both quality (particularly small, dense LDL) and quantity may increase cardiovascular risk. However, other authors have suggested that LDL size measurement does not add information beyond that obtained by measuring LDL concentration, triglyceride levels and HDL concentrations. Therefore, it remains debatable whether to measure LDL particle size in cardiovascular risk assessment and, if so, in which categories of patient. Therapeutic modulation of LDL particle size or number appears beneficial in reducing the risk of cardiovascular events, but no clear causal relationship has been shown, because of confounding factors, including lipid and non-lipid variables. Studies are needed to investigate the clinical significance of LDL size measurements in patients with coronary and non-coronary forms of atherosclerosis; in particular, to test whether LDL size is associated with even higher vascular risk, and whether LDL size modification may contribute to secondary prevention in such patients.

C-reactive protein and risk factors for peripheral vascular disease in subjects with Type 2 diabetes mellitus

AIMS

To compare the importance of different inflammatory markers and traditional risk factors in predicting peripheral vascular disease (PVD) in patients with Type 2 diabetes mellitus.

METHODS

A cross-sectional analysis of 30 Type 2 diabetic patients with PVD defined by ankle-brachial index (ABI) < 0.9, and 60 Type 2 diabetic patients without PVD (ABI > 1.0). Overnight blood was drawn and sent for study.

RESULTS

Longer diabetic duration (15 +/- 8 vs. 10 +/- 7 years, P = 0.007), higher serum creatinine level (0.11 +/- 0.04 vs. 0.09 +/- 0.03 mmol/l, P = 0.001), higher total cholesterol/high-density lipoprotein-cholesterol (TC/HDL-C) ratio (5.2 +/- 1.6 vs. 4.3 +/- 1.1, P = 0.004) and increased hypertension status (70% vs. 52%, P = 0.014) and cerebral infarction (CI) history (23% vs. 3%, P = 0.009) were noted in Type 2 diabetes with PVD. Those with PVD also showed significantly higher serum levels of C-reactive protein (CRP) (median 0.282 vs. 0.102 mg/dl, P < 0.001) and interleukin (IL)-6 (10.6 +/- 1.81 vs 1.6 +/- 4.6 pg/ml, P = 0.001). Multivariate regression analysis showed that higher serum levels of C-reactive protein (CRP), longer diabetic duration, and use of angiotensin converting enzyme inhibitor (ACEI) were independently associated with PVD in Type 2 diabetes mellitus.

CONCLUSIONS

Type 2 diabetic patients with PVD had longer diabetic duration, higher serum creatinine levels, higher TC/HDL-C ratio, higher hypertension and CI history and higher CRP and IL-6 levels. Only serum CRP level, diabetic duration, and use of ACEI were independently associated with PVD in Type 2 diabetes mellitus.

A cross-sectional study of the effects of type 2 diabetes and other cardiovascular risk factors on structure and function of nonstenotic arteries of the lower limb

OBJECTIVE

To compare intimal-medial thickness (IMT) and pulse wave conduction velocity (PWCV) in unstenosed arteries of the lower limb in subjects with and without type 2 diabetes and to determine the contribution of a range of cardiovascular risk factors.

RESEARCH DESIGN AND METHODS

IMT and PWCV were determined in lower-limb arteries of 79 subjects with diabetes and 77 euglycemic subjects. Plasma lipids were determined by enzymatic assays, and LDL particle size was measured by gradient gel electrophoresis. Lag time for copper-induced oxidation of LDL was determined. alpha-Tocopherol, retinol, and ascorbate levels were determined by high-performance liquid chromatography, soluble E-selectin by enzyme-linked immunosorbent assay, and fibrinogen and factor VII by automated assays.

RESULTS

Subjects with diabetes had greater superficial femoral artery (SFA) IMT, popliteal artery (PA) IMT, and SFA PWCV (all P < 0.0001). In univariate analysis, IMT and PWCV correlated with increased waist-to-hip ratio, triglycerides, and fibrinogen and inversely with HDL cholesterol and LDL size. Ascorbate was inversely associated with IMT, and LDL lag time was inversely correlated with PWCV. Subjects with the greatest number of features of the metabolic syndrome had the highest IMT and PWCV.

CONCLUSIONS

Adverse changes in the structure and function of unstenosed lower-limb arteries are present in type 2 diabetes and are associated with features of the metabolic syndrome.

Serum apolipoprotein AI levels in atherosclerotic and diabetic patients

OBJECTIVE

To evaluate the association between Apolipoprotein AI (ApoAI), Apolipoprotein B100 (ApoB) and the presence of lower limb atherosclerotic occlusive disease.

MATERIALS AND METHODS

Serum lipids, lipoprotein fractions, ApoAI, ApoB and Lp(a) were measured in 52 patients (28 diabetics and 24 non-diabetics) with lower limb occlusive disease. They were evaluated according to patients' glucose and compared with those in 75 healthy controls.

RESULTS

There was a significant decrease in HDL-cholesterol and ApoAI serum levels (p = 0.000001) and an increase in Lp(a) (p = 0.000001) in patients as compared to controls. No difference was observed in total cholesterol, non HDL-cholesterol or triglycerides. Multiple regression analysis revealed a significant association between low ApoAI (or HDL) levels and the disease as well as between high Lp(a) levels and the disease. ApoAI (p = 0.0003), HDL-cholesterol (p = 0.00005) and total cholesterol (p = 0.01) levels were significantly lower in diabetic patients compared to non-diabetic patients. Lp(a) levels did not correlate with fasting glucose concentration. Multiple regression analysis revealed a significant association between low ApoAI (or HDL) levels and diabetes.

CONCLUSION

Decreased ApoAI appears to be a main component of the dyslipidaemic serum profile observed in patients with atherosclerotic occlusive disease of the lower extremities. Increased Lp(a) levels is an independent risk factor. Decreased HDL-cholesterol is also involved in the dyslipidaemic profile.

Total serum homocysteine--a predictor of extracranial carotid artery stenosis in male patients with symptomatic peripheral arterial disease

High total serum homocysteine (tHcy) concentrations are associated with an increased risk of carotid artery disease in the general population. Since patients with peripheral arterial disease (PAD) have a threefold risk of cerebrovascular morbidity compared to individuals free of PAD, and since the total neurological event rate is associated with a > or = 50% lumen reduction in extracranial carotid arteries, it was tested whether tHcy is a predictor of internal carotid artery stenosis in patients with symptomatic PAD. A total of 443 consecutive male PAD patients without previous carotid surgery/stenting were studied. In all, 100 patients with PAD had an internal carotid artery stenosis > or = 50%. Of the remaining 343 patients, 100 individuals matched for age (+/- 2 years) and diabetes served as controls. The extent of carotid stenosis was evaluated with color duplex measurement; tHcy was determined by high-performance liquid chromatography. Cases displayed a significantly higher median fasting tHcy level (17.0 micromol/l) than controls (13.7 micromol/l, p=0.001). Multivariate analysis showed that tHcy (p=0.036) was an independent predictor of internal carotid artery stenosis > or = 50% in PAD patients, representing an odds ratio of 1.32 (95% CI, 1.02-1.72) for an increment of 5 micromol/l. In the present study, high tHcy was an independent risk factor for an internal carotid artery stenosis > or = 50% in patients with PAD. Since PAD patients suffer a threefold risk of stroke compared to healthy individuals, a simple vitamin substitution in PAD patients may reduce the occurrence of internal carotid artery stenosis and therefore diminish the relatively high rate of cerebrovascular events in this population.

Association between erythrocyte mean corpuscular volume and peripheral arterial disease in male subjects: a case control study

Elevated serum total homocysteine, an established risk factor for peripheral arterial disease, is influenced by the vitamin B12 and folate status. Since these vitamins are inversely correlated with erythrocyte mean corpuscular volume, an investigation of whether mean corpuscular volume is higher in patients with symptomatic peripheral arterial disease than in healthy subjects was performed. Furthermore, a determination of predictors of increased mean corpuscular volume levels in this population free of symptomatic coronary artery disease, cerebrovascular disease, and diabetes mellitus was carried out. From 469 consecutive patients with symptomatic peripheral arterial disease, 100 fulfilled study inclusion criteria. Peripheral arterial disease was confirmed by angiography. One hundred age-matched subjects without peripheral arterial disease as verified by ankle-brachial index measurements >0.9 served as control subjects. Patients with PAD displayed a significantly higher mean corpuscular volume level (94.5 fl) than control subjects (90.9 fl, p<0.001). Logistic regression analysis showed that current smoking status (p<0.001) and mean corpuscular volume (p=0.009), but not total homocysteine or lipid parameters discriminated case control status. In addition, logistic regression analysis revealed a relationship of mean corpuscular volume with smoking (p=0.001), gamma-glutamyltransferase (p<0.001), and total homocysteine (p=0.012). This model predicted mean corpuscular volume values with an accuracy of 83%. Elevated mean corpuscular volume is a predictor of symptomatic peripheral arterial disease in the sample studied. A deficiency of folate and/or vitamin B12 may be responsible for this observation, as indicated by the correlation of mean corpuscular volume with total homocysteine. Due to the additional association of mean corpuscular volume with smoking and gamma-glutamyltransferase, an unhealthy lifestyle with low vitamin intake may cause elevated mean corpuscular volume values in patients with PAD.

Peripheral vascular disease and type 2 diabetes mellitus

Patients with Type 2 diabetes mellitus frequently have peripheral vascular disease, with a predilection for the lower legs. In this review potential mechanisms for this high prevalence and altered distribution are explored. It is hypothesised that the metabolic abnormalities in the prediabetic phase predispose to a more distal and aggressive atherosclerosis. Once diabetes has developed this process is accelerated due to chronic hyperglycaemia. Furthermore, endothelial damage, non-enzymatic glycosylation and polyneuropathy could lead to impaired vascular remodelling and collateral formation.

Serum Lp(a) lipoprotein levels in patients with atherosclerotic occlusive disease of the lower extremities

OBJECTIVE

To evaluate the association between Lp(a) lipoprotein levels, other serum lipids and the presence of lower limb atherosclerotic occlusive disease.

MATERIALS AND METHODS

Angiographic findings in 36 patients were related to serum Lp(a). Total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol and Lp(a) levels were compared with those of 73 age- and sex-matched healthy controls.

RESULTS

Atheromatous lesions were localised in the femoropopliteal ( approximately 60%) and aortoiliac ( approximately 40%) segments. The number of stenosed arteries was > or =2 and the range of stenosis severity was between 40% and 100%. There was a significant increase in serum Lp(a) (p= 0.000001) and a decrease in serum HDL (p= 0.000009) levels in patients compared to controls. No difference was observed in total cholesterol, LDL-cholesterol or triglyceride. However, the ratio of total cholesterol/HDL-cholesterol was significantly higher (p= 0.005) in patients.

CONCLUSION

A dyslipidaemic serum profile, characterised by increased Lp(a) levels and decreased HDL-cholesterol levels, is associated with atherosclerotic occlusive disease of the lower extremities.

Apo E genotype, diabetes, and peripheral arterial disease in older men: the Honolulu Asia-aging study

The epsilon4 allele of the gene coding for apolipoprotein (apo) E is associated with an atherogenic lipid profile that has been linked to increased risk of coronary artery disease (CAD). Apo E genotype may also be associated with peripheral arterial disease (PAD). If present, this association may be modified by diabetes, which is also associated with dyslipidemia that predisposes to macrovascular disease. Observable associations between both ApoE genotype and diabetes with PAD may be confounded by smoking, a potent PAD risk factor that is unrelated to lipids. From 1991 to 1993, apo E genotypes (2/3, 3/3, 3/4), PAD (defined as ankle-brachial index [ABI] <0.9), diabetes (prevalent and newly-diagnosed), and smoking history (ever/never) were determined for 3,161 Japanese-American men aged 71-93. Data on hypertension and other potential confounders were also collected. Logistic regression was used to determine odds ratios (OR) between groups cross-categorized by apo E genotype and diabetes with prevalence of PAD, within strata of smoking. In each smoking stratum, non-diabetic apo epsilon3/3 carriers were considered the reference. Among ever-smokers, there was no association between apo E and PAD, regardless of diabetes status. Among never-smokers there appeared to be both apo E- and diabetes effects on PAD prevalence. Compared to the non-diabetic epsilon3/3 group, the ORS of PAD were 2.3 (1.2-4.4) and 2.0 (1.1-3.4) for epsilon3/3 newly-diagnosed and epsilon3/3 prevalent diabetic subjects, respectively. Associations were stronger among diabetic individuals in the epsilon3/4 group: the ORS were 3.0 (1.1-8.8) and 4.1 (1.9-8.7) for epsilon3/4 newly-diagnosed and epsilon3/4prevalent diabetic subjects, respectively. Despite associations whose pattern and magnitude suggested interaction between apo E genotype and diabetes on PAD prevalence among never-smokers, formal testing of this interaction did not reach statistical significance. Our finding of an apo E-PAD association among never-smokers may result from the effects of an apo epsilon4-related atherogenic lipid profile on peripheral arteries. Further studies are needed to clarify the potential mediating role of diabetes on the apo E-PAD association.

Diabetic dyslipidaemia: current treatment recommendations

Insulin deficiency and hyperglycaemia in type 1 (insulin-dependent) diabetes mellitus produce lipid abnormalities, which can be corrected by appropriate insulin therapy. Diabetic nephropathy, which is the main risk factor for coronary heart disease (CHD) in type 1 diabetes, causes pro-atherosclerotic changes in lipid metabolism. Detection and treatment of elevated cholesterol levels is likely to be of benefit in these patients. Type 2 (noninsulin-dependent) diabetes mellitus is associated with abnormal lipid metabolism, even when glycaemic control is good and nephropathy absent. Elevated triglyceride levels, reduced high density lipoprotein (HDL) cholesterol and a preponderance of small, dense low density lipoprotein (LDL) particles are the key abnormalities that constitute diabetic dyslipidaemia. The prevalence of hypercholesterolaemia is the same as for the nondiabetic population, but the relative risk of CHD is greatly increased at every level of cholesterol. Based on effectiveness, tolerability and clinical trial results, treatment with HMG-CoA reductase inhibitors to lower LDL cholesterol is recommended as primary therapy. These agents are also moderately effective at reducing triglyceride and increasing HDL cholesterol levels. If hypertriglyceridaemia predominates, treatment with fibric acid derivatives is appropriate, although there is currently only limited clinical trial evidence that the risk of CHD will be reduced. In type 1 diabetes, but particularly in type 2 diabetes, lipid disorders are likely to contribute significantly to the increased risk of macrovascular complications. especially CHD. Management of the disordered lipid metabolism should be given a high priority in the clinical care of all patients with diabetes.