Systemic arterial compliance is reduced in young patients with IDDM

Arterial stiffness is not increased in teens with early uncomplicated type 1 diabetes mellitus

People with type 1 diabetes mellitus are at an increased risk of cardiovascular mortality. Studies comparing arterial stiffness between subjects with type 1 diabetes and nondiabetic controls have provided controversial findings.We investigated brachial–ankle pulse wave velocity (baPWV) in 87 teenagers with type 1 diabetes mellitus and in 21 matched healthy controls. Our data show that baPWV was not increased in teenagers after a median illness of 5 years.

Cardiac autonomic function correlates with arterial stiffness in the early stage of type 1 diabetes

Arterial stiffness is increased in type 1 diabetes (T1D), before any clinical complications of the disease are evident. The aim of the present paper was to investigate the association between cardiac autonomic function and arterial stiffness in a cohort of young T1D patients, without history of hypertension and any evidence of macrovascular and/or renal disease. Large artery stiffness was assessed by measurement of carotid-femoral pulse wave velocity (PWV). Cardiac autonomic function was assessed by the cardiovascular tests proposed by Ewing and Clarke. Patients with a high cardiac autonomic neuropathy score (≥4) had significantly higher PWV than those with a low score (0-1). A negative, heart rate-independent, correlation between PWV and heart rate variation during respiration was observed (r = -0.533,  P < 0.001). In multivariable analysis, E/I index was the strongest correlate of PWV (β-coefficient = -0.326, P = 0.002). Cardiac parasympathetic function is a strong predictor of large arterial stiffness, in young T1D patients free of macrovascular and renal complications.

Quantitative analysis of the postcontractile blood-oxygenation-level-dependent (BOLD) effect in skeletal muscle

Previous studies show that transient increases in both blood flow and magnetic resonance image signal intensity (SI) occur in human muscle after brief, single contractions, and that the SI increases are threefold larger in physically active compared with sedentary subjects. This study examined the relationship between these transient changes by measuring anterior tibial artery flow (Doppler ultrasound), anterior muscle SI (3T, one-shot echo-planar images, TR/TE = 1,000/35), and muscle blood volume and hemoglobin saturation [near-infrared spectroscopy (NIRS)] in the same subjects after 1-s-duration maximum isometric ankle dorsiflexion contractions. Arterial flow increased to a peak 5.9 ± 0.7-fold above rest (SE, n = 11, range 2.6-10.2) within 7 s and muscle SI increased to a peak 2.7 ± 0.6% (range 0.0-6.0%) above rest within 12 s after the contractions. The peak postcontractile SI change was significantly correlated with both peak postcontractile flow (r = 0.61, n = 11) and with subject activity level (r = 0.63, n = 10) estimated from 7-day accelerometer recordings. In a subset of 7 subjects in which NIRS data acquisition was successful, the peak magnitude of the postcontractile SI change agreed well with SI calculated from the NIRS blood volume and saturation changes (r = 0.80, slope = 1.02, intercept = 0.16), confirming the blood-oxygenation-level-dependent (BOLD) mechanism underlying the SI change. The magnitudes of postcontractile changes in blood saturation and SI were reproduced by a simple one-compartment muscle vascular model that incorporated the observed pattern of postcontractile flow, and which assumed muscle O(2) consumption peaks within 2 s after a brief contraction. The results show that muscle postcontractile BOLD SI changes depend critically on the balance between O(2) delivery and O(2) consumption, both of which can be altered by chronic physical activity.

Subclinical vascular alterations in young adults with type 1 diabetes detected by arterial tonometry

BACKGROUND

Diabetes mellitus is characterized by a very high prevalence of atherosclerotic disease. Aims of this study were to determine arterial compliance parameters in type 1 diabetes (T1D) patients as an expression of early pre-clinical endothelial dysfunction and to evaluate the impact of glucose exposure parameters such as the duration of diabetes and glycosylated haemoglobin (HbA(1c)) on the risk of developing alterations in vascular compliance.

METHODS

23 patients with uncomplicated type 1 diabetes (mean age: 32.78 +/- 9.06 years, mean disease duration: 10.78 +/- 7.51 years, mean HbA(1c) levels: 7.7 +/- 1.9) and 26 age- and sex-matched healthy subjects (mean age: 32.3 +/- 8.51 years) were recruited. In these subjects, we evaluated arterial compliance by calibrated tonometry (HDI/Pulsewave() CR-2000). Parameters included the following: large artery elasticity (C1), small artery elasticity (C2), systemic vascular resistance (SVR) and total vascular impedance (TVI).

RESULTS

Patients with longer duration of T1D (>10 years) showed significant alterations in C2 (4.97 +/- 2.7 mL/mmHg x 100) and in SVR (1464.67 +/- 169.16 dina x s x cm(-5)) when compared with both healthy individuals (C2: 8.28 +/- 2.67 mL/mmHg x 100, p = 0.001; SVR: 1180.58 +/- 151.55 dina x s x cm(-5), p = 0.01) and patients with recent-onset disease (<or=10 years) (C2: 10.02 +/- 3.6 mL/mmHg x 100, p < 0.001; SVR: 1124.18 +/- 178.5 dina x s x cm(-5), p < 0.000). Both disease duration and HbA(1c) independently predicted impaired arterial compliance.

CONCLUSIONS

Young adult T1D patients with no signs of disease complication have detectable vessel wall abnormalities, particularly of small arteries, suggestive of hyperglycaemia-related early endothelial dysfunction.

Autoimmunity and atherosclerosis: the presence of antinuclear antibodies is associated with decreased carotid elasticity in young women. The Cardiovascular Risk in Young Finns Study

OBJECTIVE

There is ample evidence demonstrating that accelerated atherosclerosis prevails in autoimmune rheumatic diseases, particularly in SLE, and that the risk is due not only to traditional cardiovascular risk factors but also to the disease itself. ANAs are a hallmark of SLE and are known even to antedate the development of SLE. Our aim was to investigate whether positive ANAs in young adults are associated with risk factors for atherosclerosis or subclinical markers of atherosclerosis.

METHODS

ANAs were examined by IIF using HEp-2 cells as substrate in 2278 participants in the Cardiovascular Risk in Young Finns Study for whom detailed data on cardiovascular risk factors and markers of subclinical atherosclerosis (including brachial flow-mediated dilatation, carotid compliance and carotid intima-media thickness) were available.

RESULTS

In multivariate analyses, adjusted for age, BMI, serum concentrations of CRP, triglycerides, high-density lipoprotein and low-density lipoprotein cholesterol, blood pressure and smoking habits, ANA positivity (titre > 160) was inversely associated (beta = -0.145; P = 0.034) with carotid compliance in women.

CONCLUSIONS

Our results indicate that ANA positivity is associated with decreased carotid elasticity in women, suggesting that mechanisms resulting in ANA production may be involved in the development of early atherosclerosis.

Arterial stiffness in diabetes and the metabolic syndrome: a pathway to cardiovascular disease

Increased arterial stiffness associated with diabetes and the metabolic syndrome may in part explain the increased cardiovascular disease risk observed in these conditions. Arterial stiffness can be estimated by quantifying pulse pressure but is better described by distensibility and compliance coefficients, pulse wave velocity and wave reflection. The most common non-invasive methodologies used to quantify these estimates of arterial stiffness (e.g. ultrasonography and applanation tonometry) are also described. We then review and summarise the current data on the associations between diabetes, the metabolic syndrome and insulin resistance on the one hand and greater arterial stiffness on the other, and identify and discuss some unresolved issues such as differential stiffening of central vs peripheral arterial segments, the impact of sex, and the pathobiology of increased arterial stiffness in diabetes and the metabolic syndrome. Finally, some considerations with regard to treatment options are presented. At present the most powerful therapy available for reducing arterial stiffness is to vigorously treat hypertension using pharmacological agents. New pharmacological strategies to reduce arterial stiffness are likely to be especially relevant to individuals with diabetes.

Squatting amplifies pulse pressure increase with disease duration in patients with type 1 diabetes

OBJECTIVE

To evaluate pulse pressure changes according to duration of type 1 diabetes and to assess the influence of posture.

RESEARCH DESIGN AND METHODS

We performed continuous measurement of blood pressure with a Finapres device during a 3 x 1 min posture test (standing, squatting, standing) in 159 type 1 diabetic patients divided into four groups according to diabetes duration (<or=10, 11-20, 21-30, and >30 years, groups 1-4, respectively) and compared the results with those of age-matched nondiabetic subjects.

RESULTS

Pulse pressure progressively increased according to type 1 diabetes duration (P < 0.0001), especially in women, but not in age-matched nondiabetic subjects (NS). Pulse-pressure increase from group 1 to group 4 was amplified in the squatting position (from 50 +/- 17 to 69 +/- 14 mmHg) compared with standing (from 44 +/- 15 to 55 +/- 12 mmHg).

CONCLUSIONS

Pulse pressure increases according to type 1 diabetes duration more in women than in men, and the squatting position sensitizes such pulse-pressure increase in both sexes.

Endothelial function and arterial stiffness in uncomplicated type 1 diabetes and healthy controls and the impact of insulin on these parameters during an euglycemic clamp

BACKGROUND

In addition to its role in glucose metabolism, insulin has shown to exert numerous vascular effects, and an impaired vascular function of insulin is assumed to be a major contributor in the development of vascular complications. Arterial augmentation (AP) and the augmentation index (Aix) are surrogate parameters of arterial stiffness and are commonly used as predictors for cardiovascular risk. The aim of this study is to investigate the effect of insulin on arterial stiffness and parameters of endothelial function in patients with type 1 diabetes and healthy control subjects.

METHODS

Fourteen patients with type 1 diabetes (six male, eight female) with a mean age of 36.6 +/- 11.8 years and 14 healthy subjects (seven male, seven female) with a mean age of 27.3 +/- 5.5 years were randomized to an euglygemic clamp with either a low (0.25 mU/kg/min) or a high (1.0 mU/kg/min) insulin dose on two different days. The mean HbA1c in the diabetic subjects was 7.3 +/- 0.7%. In these subjects, arterial stiffness was measured by pulse wave analysis (SphygmoCor, AtCor Medical, Australia). AP was calculated as the difference between the second and the first systolic shoulders of the central pressure wave curve, and the Aix was expressed as the percentage of AP from total pulse pressure. As parameters of endothelial function, cyclic guanosine monophosphate, nitrotyrosine, and asymmetric dimethylarginine were determined at baseline and after 120 minutes.

RESULTS

Patients with type 1 diabetes showed increased values for AP with 3.5 +/- 3.1 mm Hg and Aix with 12.5 +/- 12.5% compared to healthy controls with -0.7 +/- 2.6 mm Hg for AP and -4.2 +/- 10.6% for Aix. This difference was statistically significant (p < 0.01). During the euglycemic clamp, insulin improved, but did not normalize the increased values for AP and Aix in patients with type 1 diabetes. Concerning parameters of endothelial function, patients with type 1 diabetes showed statistically significant increased values for nitrotyrosine compared to healthy controls at baseline [low insulin: diabetes mellitus (DM) 1993.12 +/- 1330.85 nmol/liter vs healthy controls 803.7 +/- 726.91; high insulin DM: 2208.02 +/- 1736.57 nmol/liter vs healthy controls: 750.83 +/- 426.03 nmol/liter] (p < 0.05).

CONCLUSION

Patients with type 1 diabetes mellitus revealed an increased arterial stiffness measured as augmentation and augmentation index and increased nitrotyrosine levels as a marker of oxidative stress compared to healthy control subjects at baseline. Application of insulin improves the arterial elastic properties, but was not able to normalize the vascular function in patients with type 1 diabetes.

Relationship Between Glycosylated Hemoglobin and Arterial Elasticity

Arterial elasticity is decreased in diabetes, but it is unclear whether there is a relationship between glycosylated hemoglobin (HbA1c) and arterial elasticity. To evaluate this question, 111 subjects with diabetes mellitus had HbA1c and arterial elasticity determined in an academic outpatient setting. Three measurements of arterial elasticity indices were obtained supine using the HDI/PulseWave CR-2000 Research CardioVascular Profiling System (Hypertension Diagnostics Inc., Eagan, MN). The study population was 49% black and 51% women. Population characteristics included age, 49.2 years; duration of diabetes, 12.1 years; HbA1c, 8.9%; large artery elasticity, 11.8 mL/mm Hg x 10; and small artery elasticity, 4.7 mL/mm Hg x 100. Age correlated with diminished large artery elasticity. Women had a lower large artery elasticity than men (10.6 vs. 13.3 mL/mm Hg x 10; p = 0.0002). Decreasing small artery elasticity was associated with increasing age (p = 0.0001), HbA1c (p = 0.0184), and African-American ethnicity (p = 0.0306). Women had less small artery elasticity than men (3.8 vs. 5.8 mL/mm Hg x 100; p = 0.0001). Black diabetic patients had a reduced arterial elasticity compared with whites. Increasing HbA1c is associated with decreasing small artery elasticity, but not large artery elasticity. In diabetic patients, small artery elasticity is reduced to a greater extent in women than men and in blacks than whites.

Arterial stiffness in type 1 diabetes mellitus is aggravated by autoimmune thyroid disease

OBJECTIVE

The aim of our study was to measure arterial stiffness in patients with Type 1 diabetes mellitus, its contributing factors and its relation to macrovascular arterial changes.

MATERIALS AND METHODS

Thirty-one female Type 1 diabetic patients were studied; 11 had concomitant autoimmune thyroid disease although euthyroid during the study period. Stiffness was studied using applanation tonometry and pulse wave analysis for evaluation of systolic arterial pressure augmentation secondary to arterial stiffening and early wave reflection. Results were compared to 24 healthy individuals. In all patients, endothelium-related flow-mediated dilation (FMD) of the brachial artery and intima-media thickness (IMT) of the carotid artery were measured.

RESULTS

Augmentation pressure (AP) and augmentation index (AI) were higher in Type 1 diabetic patients suggesting stiffer arteries compared to controls (AP: 5.8 +/- 3.6 vs 2.8 +/- 2.2 mmHg, p < 0.001; and AI:18.3 +/- 9 vs 11.1 +/- 8.8%, p = 0.004). The subgroup of diabetic patients with autoimmune thyroid disease presented stiffer arteries than those without (AP: 6.5 +/- 2.9 vs 5.5 +/- 3.9 mmHg, p < 0.05; and AI: 21.3 +/- 5.4 vs 16.7 +/- 10.3%, p < 0.05), though the two groups did not differ statistically by means of age, disease duration, hemoglobin A1c (HbA1c), lipid levels, FMD and IMT. In multiple regression analysis, variables independently associated to AI in the diabetes group were: age (p = 0.028), IMT of the carotid artery bifurcation (p = 0.045), disease duration (p = 0.031) and autoimmune thyroid disease (p = 0.015). No correlation was observed between AI and metabolic control, blood pressure, microalbuminuria, presence of retinopathy and endothelial function (FMD).

CONCLUSIONS

Women with Type 1 diabetes have increased arterial stiffness, which indicates macroangiopathy. An independent correlation between these indices and carotid IMT was observed. Concomitant autoimmune thyroid disease seems to aggravate arterial compliance in these patients, a finding that merits further investigation.

Assessment of flow-mediated vasodilatation (FMD) of the brachial artery: effects of technical aspects of the FMD measurement on the FMD response

AIMS

The ability to assess endothelial function non-invasively with B-mode ultrasound has lead to its widespread application in a variety of studies. However, the absolute values obtained using this approach vary considerably across studies. We studied whether technical aspects of the methodology can explain the wide variety in absolute values across studies.

METHODS AND RESULTS

A literature search was performed to identify published reports on flow-mediated vasodilatation (FMD) of the brachial artery published between 1992 and 2001. Information on type of equipment (wall track/B-mode), location of the measurement (antecubital fossa/upper arm), occlusion site (lower/upper arm), occlusion duration (min), and occlusion pressure was extracted. Patient characteristics were also extracted. For the healthy populations, mean FMD varied from 0.20 to 19.2%; for the coronary heart disease (CHD) patients FMD varied from -1.3 to 14%; for subjects with diabetes mellitus FMD varied from 0.75 to 12%. Compared with occlusion at the upper arm, lower arm occlusion was related to decreased FMD (mean difference in FMD -2.47%; 95% CI 0.55-4.39). An occlusion duration of > or =4.5 min was related to an increased FMD compared with an occlusion time of < or =4 min (mean difference 1.30%; 95% CI 0.35-2.46). These findings were adjusted for other technical aspects of the methodology and for differences in risk factors between populations.

CONCLUSION

Mean FMD differs widely between studies. There is a great overlap between populations (healthy, CHD, diabetics). Our findings suggest that the technical aspects of the measurements, the location, and the duration of the occlusion may explain some of these differences, whereas type of equipment, location of the measurement, and occlusion pressure do not.

Use of arterial transfer functions for the derivation of central aortic waveform characteristics in subjects with type 2 diabetes and cardiovascular disease

OBJECTIVE

Optimal blood pressure control in subjects with diabetes reduces cardiovascular complications. There is theoretical benefit in the assessment of central aortic waveforms including the augmentation index, which is taken as a putative index of stiffness. Transfer functions may be used to reconstruct aortic from radial pressure waveforms; however, a single generalized transfer function may not be appropriate for all patients. We aimed to evaluate the technique in subjects with diabetes.

RESEARCH DESIGN AND METHODS

Simultaneous invasive central aortic and noninvasive radial waveforms were acquired in 19 subjects with type 2 diabetes, and a diabetes-specific transfer function was derived. Similar data were acquired from 38 age- and sex-matched subjects without diabetes. Central waveforms were reconstructed using a generalized transfer function in all patients and the diabetes-specific transfer function in individuals with diabetes.

RESULTS

There was no difference between groups in measured central pressures. The error in generalized transfer function-derived systolic pressure was greater in individuals with diabetes (6 +/- 7 mmHg) (mean +/- SD) than without diabetes (2 +/- 8 mmHg) (P<0.05). Errors in other parameters were no different. The diabetes-specific transfer function reduced the error in derived systolic pressure to 0 +/- 7 mmHg in individuals with diabetes--no different than that with the generalized transfer function in individuals without diabetes. The central augmentation index reconstructed by either transfer function was unrelated to that directly measured.

CONCLUSIONS

A generalized transfer function is inappropriate for the derivation of central waveforms in subjects with type 2 diabetes. Errors in subjects with diabetes might be reduced with a diabetes-specific transfer function.

The ocular hemodynamic response to nitric oxide synthase inhibition is unaltered in patients with early type I diabetes

BACKGROUND

An impaired ocular hemodynamic response to systemic nitric oxide synthesis inhibition has been demonstrated in patients with long-standing insulin-dependent diabetes mellitus. It is unclear whether this altered responsiveness is already detectable in early uncomplicated type I diabetes.

METHODS

The effect of the nitric oxide synthase inhibitor N(G)-monomethyl- l-arginine (L-NMMA) was studied in 10 male patients with early type I diabetes under euglycemic conditions and 10 healthy matched control subjects in a single (analyst) blinded cohort study design. Changes in ocular hemodynamics (fundus pulsation amplitude, mean flow velocity in the ophthalmic artery) and in pulse rate and mean blood pressure were measured in response to systemic intravenous doses of 1.5, 3, and 6 mg/kg L-NMMA.

RESULTS

L-NMMA dose-dependently and significantly decreased fundus pulsation amplitude (-21.0% vs -23.3% in diabetics and controls, respectively), mean flow velocity in the ophthalmic artery (-12.3% vs -10.8%) and pulse rate (-15.4% vs -16.6%) and increased mean arterial pressure (+19.5% vs +14.7%). The ocular and systemic hemodynamic effects of L-NMMA were not different between patients with diabetes and controls.

CONCLUSION

The responsiveness of the choroidal vasculature and the ophthalmic artery to L-NMMA is not altered in early type 1 diabetes. An impaired hemodynamic response to nitric oxide synthesis inhibition in diabetes is therefore not caused by a primary defect but rather due to altered vascular responsiveness secondary to long-standing disease.

The aging of elastic and muscular arteries: a comparison of diabetic and nondiabetic subjects

OBJECTIVE

To compare age-related changes in the mechanical properties of different arterial segments in normal volunteers and subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In 169 subjects (diabetic n = 57 and nondiabetic n = 112), we assessed the mechanical properties of three arterial segments of differing wall composition. Pulse wave velocity (PWV) was measured noninvasively in a thoraco-abdominal segment (carotid femoral PWV [PWV(cf)]), in an upper limb muscular artery (carotid radial PWV [PWV(cr)]), and from the aorta to the finger (PWV from the aorta to the finger [PWV(fin)]). Central aortic compliance (CAC) was also measured.

RESULTS

Average CAC was lower (0.662 vs. 0.850, P < 0.05) and all measures of PWV tended to be faster in diabetic subjects despite the fact that they were, on average, 10 years younger. However, these measures were not related to age in diabetic subjects. After correcting for blood pressure, only PWV(cf) was associated with age in nondiabetic subjects (P < 0.001). Expressing results as ratios of nonelastic to elastic arterial segments (i.e., PWV(cr)-to-PWV(cf) and PWV(fin)-to-PWV(cf)) improved the relationship with age. Both PWV(cr)-to-PWV(cf) and PWV(fin)-to-PWV(cf) were significantly associated with age in nondiabetic subjects (r = -0.59, P < 0.001; r = -0.57, P < 0.001) but not in diabetic subjects (r = -0.15, P = 0.302; r = -0.24, P = 0.129). Multivariate analysis showed that the ratios were not associated with systolic blood pressure.

CONCLUSIONS

There are significant differences in the rate of age-related decline in vascular stiffness in elastic arteries of nondiabetic compared with diabetic arteries. Diabetic arteries appear to age at an accelerated rate at an earlier age and then reach a functional plateau.

Vascular compliance in diabetes

The measurement of vascular compliance has assumed increasing importance as a powerful predictor of cardiovascular and all-cause mortality. Arterial stiffness increases with the duration of diabetes, older age, and concomitant hypertension. Hyperglycemia may increase arterial stiffness in diabetes by reducing the bioactivity of endothelium-derived nitric oxide (NO) either by decreasing NO production or inactivating NO by interaction with oxygen-derived free radicals. New approaches to therapy, such as the use of advanced glycation end product "breakers," may potentially benefit patients with diabetes.

Comparison of generalized and gender-specific transfer functions for the derivation of aortic waveforms

Arterial transfer functions have been promoted for the derivation of central aortic waveform characteristics not usually accessible noninvasively, but possibly of prognostic significance. The utility of generalized rather than gender-specific transfer functions has not been assessed. Invasive central aortic and noninvasive radial (Millar Mikro-tip tonometer) blood pressure waveforms were recorded simultaneously in 78 subjects (61 male and 17 female). Average transfer functions were obtained for the whole group and for each gender by two methods. Reverse transformation was performed with the use of each transfer function. Measured aortic waveform parameters were compared with those derived using average, gender-appropriate, and gender-inappropriate transfer functions. Differences in central waveform characteristics were demonstrated between men and women. Derived waveform parameters were significantly different from measured values [e.g., subendocardial viability index and augmentation index (P < 0.001)]. A gender-appropriate transfer function significantly improved the derivation of some parameters, including systolic pressure and systolic and diastolic pressure time integrals (P < 0.05). Generalized arterial transfer functions may not be universally applicable across all waveform parameters of potential interest, and gender-specific transfer functions may be more appropriate.

Vascular compliance is reduced in the early stages of type 1 diabetes

OBJECTIVE

To determine whether arterial compliance of patients with type 1 diabetes is reduced before the development of clinically apparent diabetes complications.

RESEARCH DESIGN AND METHODS

Pulse-wave analysis was used to compare vascular compliance between patients with type 1 diabetes and nondiabetic control subjects. Analysis of covariance was used to determine differences between the two groups with adjustment for age if needed.

RESULTS

A total of 59 patients with type 1 diabetes were studied; age ranged from 17-61 years. Of the 59 patients, 32 had no evidence of diabetes complications and 27 had microvascular complications. The control group consisted of 57 healthy subjects ranging in age from 23-79 years. In the control group, large artery compliance (C1) and small artery compliance (C2) were inversely proportional to age (r = -0.55 for C1 and -0.50 for C2; P < 0.01). When the control subjects were compared with type 1 diabetic patients without microvascular complications, C1 was 1.51 +/- 0.04 (SEM) for the control group and 1.33 +/- 0.06 (SE) ml/mmHg for the diabetic group, whereas C2 was 0.080 +/- 0.005 (SE) and 0.065 +/- 0.005 (SE) ml/mmHg for the control and diabetic subjects, respectively, when adjusted for age (P = 0.03 for both C1 and C2).

CONCLUSIONS

Vascular compliance of both the large and small arteries is reduced in type 1 diabetic patients before any clinical complications from the diabetes are evident. This study serves to emphasize that vascular changes occur at an early point in the disease and may increase risk of cardiovascular events in patients with diabetes. Larger prospective studies are required to confirm this finding and to investigate the efficacy of medical intervention.