Carotid intima-media thickness and apolipoprotein B/apolipoprotein A-I ratio in middle-aged patients with Type 2 diabetes

Plasma mid-regional pro-atrial natriuretic peptide predicts cardiovascular events in patients with type 2 diabetes independently of subclinical organ damage

AIM

The aim of this study was to investigate the association between plasma MR-proANP and cardiovascular disease (CVD) in a middle-aged population with type 2 diabetes.

METHODS

MR-proANP was measured in 690 patients with type 2 diabetes participating in the epidemiological study CARDIPP (Cardiovascular Risk Factors in Patients with Diabetes-a Prospective Study in Primary Care). The outcome variables were incident major adverse cardiovascular events (MACE) and all-cause mortality. Patients were followed using the national Swedish Cause of Death Registry and the Inpatient Register.

RESULTS

During the mean follow-up period of 10.8 years, MACE occurred in 111 patients and 102 patients died. The hazard ratio for an increment of MR-proANP of 1 pmol/l adjusted for sex, age, current smoking, previous CVD, HbA1c, serum cholesterol, eGFR, systolic blood pressure, C-reactive protein, aortic pulse wave velocity, left ventricular mass and intima media thickness in the carotid arteries was 1.007 (95% CI 1.000-1.013, P = 0.042) for MACE and 1.008 (95% CI 1.001-1.014, P = 0.017) for all-cause mortality.

CONCLUSIONS

Elevated MR-proANP levels predict an increased risk for MACE and all-cause mortality in patients with type 2 diabetes independently of CVD risk factors and markers for subclinical organ damage.

Plasma Protein Profile of Carotid Artery Atherosclerosis and Atherosclerotic Outcomes: Meta-Analyses and Mendelian Randomization Analyses

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Clinical Utility of the Logarithmically Transformed Ratio of Triglycerides-to- High-Density Lipoprotein Cholesterol and Its Relationship with Other Atherosclerosis-Related Lipid Factors in Type 2 Diabetes

Background: Elevated triglyceride (TG) levels and reduced high-density lipoprotein-cholesterol (HDL-c) levels indicate lipid abnormalities, but their levels alone do not reflect the actual status of plasma atherogenicity and cardiovascular disease risk (CVD). TG and HDL-c levels directly affect the balance between plasma atherogenic and antiatherogenic factors, as well as values of the atherogenic index of plasma [AIP (logarithmically transformed ratio of TG-to-HDL-c)]. The aim of this study was to evaluate the AIP risk categories (an indicator of plasma atherogenicity) and the relationships of AIP with other atherosclerosis-related lipid parameters in patients with type 2 diabetes mellitus (T2DM) and their potential clinical utility. Methods: Standard lipid profile, AIP, and lipid hydroperoxides (LOOH) were investigated in 124 T2DM outpatients (mean age 52.7 ± 5.9 years) and 61 healthy subjects (mean age 50.9 ± 6.8 years). T2DM patients were subclassified according to the AIP risk category and glycemic control. Results: Higher levels of AIP, LOOH, and TG and lower HDL-c (all P < 0.0001) were observed in T2DM patients than in the control group. AIP positively correlated with LOOH, non-HDL-c, and the non-HDL/HDL ratio (all P < 0.0001). The TG level was strongly correlated with the LOOH level among T2DM patients (P < 0.0001). Conclusions: The close association of AIP with other atherosclerosis-related lipid factors reveals an increased plasma atherogenicity. AIP risk categories indicate the actual status of plasma atherogenicity and identify subjects who are at an increased atherogenic risk and the development of CVD. In this respect, AIP has a promising future in routine clinical practice.

Using proximity extension proteomics assay to discover novel biomarkers associated with circulating leptin levels in patients with type 2 diabetes

We aimed to discover novel associations between leptin and circulating proteins which could link leptin to the development of cardiovascular disease in patients with type 2 diabetes (T2DM). In a discovery phase, we investigated associations between 88 plasma proteins, assessed with a proximity extension assay, and plasma leptin in a cohort of middle-aged patients with T2DM. Associations passing the significance threshold of a False discovery rate of 5% (corresponding to p < 0.0017) were replicated in patients with T2DM in an independent cohort. We also investigated if proteins mediated the longitudinal association between plasma leptin and the incidence of major cardiovascular events (MACE). One protein, adipocyte fatty acid binding protein (A-FABP), was significantly associated with leptin in both the discovery phase [95% CI (0.06, 0.17) p = 0.00002] and the replication cohort [95% CI (0.12, 0.39) p = 0.0003]. Multiplicative interaction analyses in the two cohorts suggest a stronger association between A-FABP and leptin in men than in women. In longitudinal analyses, the association between leptin and MACE was slightly attenuated after adding A-FABP to the multivariate model. Our analysis identified a consistent association between leptin and A-FABP in two independent cohorts of patients with T2DM, particularly in men.Trial registration: ClinicalTrials.gov identifier NCT01049737.

Toe brachial index predicts major acute cardiovascular events in patients with type 2 diabetes independently of arterial stiffness

OBJECTIVE

Our aim was to analyze the predictive value of toe brachial index (TBI) as a risk marker for future major adverse cardiovascular events (MACE) and all-cause mortality in patients with type 2 diabetes (T2D).

METHODS

TBI was measured in 741 patients with T2D in 2005-2008. Conventional risk factors for vascular disease as well as non-invasive measurements such as pulse-wave velocity (PWV) and intima-media thickness (IMT) of the carotid arteries were estimated. MACE was defined as cardiovascular death or hospitalization for non fatal myocardial infarction or non fatal stroke. Patients were followed for incidence of MACE using the national Swedish Cause of Death Registry and the Inpatient Register.

RESULTS

During the follow-up for a period of 9 years MACE occurred in 97 patients and 85 patients died. TBI tertile, 1 versus 3, was significantly related to MACE (HR 2.67, 95%CI 1.60-4.50; p < 0.001) and to all-cause mortality (HR 1.98, 95%CI 1.16-3.83; p = 0.01). TBI tertile 1 as compared to TBI tertile 3 predicted MACE, but not all-cause mortality, independently of age, sex, diabetes duration and treatment, antihypertensive treatment, previous cardiovascular diseases, office systolic blood pressure, HbA1c, LDL cholesterol, estimated glomerular filtration rate, body mass index, current smoking PWV, IMT and carotid plaque presence (HR 3.39, 95%CI 1.53-7.51; p = 0.003 and HR 1.81, 95%CI 0.87-3.76; p = 0.1, respectively).

CONCLUSIONS

Low TBI predicts an increased risk for MACE independently of arterial stiffness in patients with type 2 diabetes.

TRIAL REGISTRATION

Clinical Trials.gov number NCT01049737. Registered January 14, 2010.

Variation of Carotid Intima Media Thickness With Body Mass Index in Healthy Adults of Black African Descent

OBJECTIVES

Studies have shown that common carotid intima media thickness (CIMT) measured by B-mode sonography increases with body mass index (BMI) among subjects with cardiovascular diseases in different populations. However, association of body fat and subclinical atherosclerosis in the absence of these cardiovascular diseases is understudied. We aimed to evaluate the correlation between BMI and CIMT in a healthy adult population of black African ancestry.

METHODS

This is a cross-sectional prospective study in 300 consecutive apparently healthy subjects aged 18 to 70 years without history of hypertension, dyslipidemia, diabetes mellitus, and renal disease. Subjects' common carotid artery intima media thickness was measured with a 7.5-MHz linear ultrasound transducer at a point 10 mm proximal to the carotid bulb. All subjects' biodata, medical history, anthropometric (weight and height from which BMI was calculated), laboratory (fasting lipid profile and blood glucose), and CIMT values were recorded on a pro forma. Data were analysed using SPSS version 21, and significant P was set at less than .05.

RESULTS

The right, left, and average CIMT of both sides in our study subjects are 0.52 ± 0.11 mm, 0.51 ± 0.11 mm and 0.52 ± 0.11 mm respectively, with no significant difference between the right and left sides (P > .05). The right, left, and average CIMT increased with increasing age and BMI category (all P < .01) but were not significantly different between men and women (all P > .05). Age (r = .824, .825, and .827; P < .01) and BMI (r = .503, .504, .507; P < .01) had strong positive correlations with right, left, and average CIMT.

CONCLUSIONS

Increasing age and BMI category, but not sex, significantly influenced CIMT values in our apparently healthy black African population.

Multiplex proteomics for prediction of major cardiovascular events in type 2 diabetes

AIMS/HYPOTHESIS

Multiplex proteomics could improve understanding and risk prediction of major adverse cardiovascular events (MACE) in type 2 diabetes. This study assessed 80 cardiovascular and inflammatory proteins for biomarker discovery and prediction of MACE in type 2 diabetes.

METHODS

We combined data from six prospective epidemiological studies of 30-77-year-old individuals with type 2 diabetes in whom 80 circulating proteins were measured by proximity extension assay. Multivariable-adjusted Cox regression was used in a discovery/replication design to identify biomarkers for incident MACE. We used gradient-boosted machine learning and lasso regularised Cox regression in a random 75% training subsample to assess whether adding proteins to risk factors included in the Swedish National Diabetes Register risk model would improve the prediction of MACE in the separate 25% test subsample.

RESULTS

Of 1211 adults with type 2 diabetes (32% women), 211 experienced a MACE over a mean (±SD) of 6.4 ± 2.3 years. We replicated associations (<5% false discovery rate) between risk of MACE and eight proteins: matrix metalloproteinase (MMP)-12, IL-27 subunit α (IL-27a), kidney injury molecule (KIM)-1, fibroblast growth factor (FGF)-23, protein S100-A12, TNF receptor (TNFR)-1, TNFR-2 and TNF-related apoptosis-inducing ligand receptor (TRAIL-R)2. Addition of the 80-protein assay to established risk factors improved discrimination in the separate test sample from 0.686 (95% CI 0.682, 0.689) to 0.748 (95% CI 0.746, 0.751). A sparse model of 20 added proteins achieved a C statistic of 0.747 (95% CI 0.653, 0.842) in the test sample.

CONCLUSIONS/INTERPRETATION

We identified eight protein biomarkers, four of which are novel, for risk of MACE in community residents with type 2 diabetes, and found improved risk prediction by combining multiplex proteomics with an established risk model. Multiprotein arrays could be useful in identifying individuals with type 2 diabetes who are at highest risk of a cardiovascular event.

Apolipoprotein B/apolipoprotein A1 ratio and mortality among incident peritoneal dialysis patients

BACKGROUND

To investigate the association between the ratio of apolipoprotein B (apo B) / apolipoprotein A1 (apo A1) with all-cause mortality and cardiovascular events in peritoneal dialysis (PD) patients.

METHODS

Eight hundred and sixty incident PD patients were enrolled from November 1, 2005, to February 28, 2017, and followed until May 31, 2017. Outcomes were all-cause mortality and cardiovascular events. Associations between the apo B/apo A1 ratio with all-cause mortality and cardiovascular events were evaluated using multivariable-adjusted Cox models.

RESULTS

Of the 860 patients, the mean age was 49.9 ± 14.5 years, 57.6% were men, and 19.3% were diabetic patients. The median apo B/apo A1 ratio was 0.65 (range: 0.22-2.24). During a median follow-up period of 27 months (interquartile range, 13 - 41 months), 202 deaths, and 145 cardiovascular events were recorded. After adjustment for age, sex, body mass index, diabetes, cardiovascular disease, systolic blood pressure, total Kt/V, estimated glomerular filtration rate, hemoglobin level, neutrophil to lymphocyte ratio and albumin, triglyceride, and cholesterol, as well as the use of lipid-lowering agents, the highest apo B/apo A1 ratio tertile was significantly associated with a hazard ratio for all-cause mortality of 1.60 (95% CI: 1.02 to 2.49, P = 0.040) and for cardiovascular events of 2.04 (95% CI: 1.21 to 3.44, P = 0.008).

CONCLUSION

An increased apo B/apo A1 ratio was independently associated with all-cause mortality and cardiovascular events in PD patients.

Apolipoprotein-defined lipoprotein subclasses, serum apolipoproteins, and carotid intima-media thickness in T1D

Circulating apolipoprotein-defined lipoprotein subclasses (ADLS) and apolipoproteins predict vascular events in the general and type 2 diabetes populations, but data in T1D are limited. We examined associations of ADLS, serum apolipoproteins, and conventional lipids with carotid intima-media thickness (IMT) measured contemporaneously and 6 years later in 417 T1D participants [men: n = 269, age 42 ± 6 y (mean ± SD); women: n = 148, age 39 ± 8 y] in the Epidemiology of Diabetes Interventions and Complications study, the follow-up of the Diabetes Control and Complications Trial (DCCT). Date were analyzed by multiple linear regression stratified by sex, and adjusted for time-averaged hemoglobin A1C, diabetes duration, hypertension, BMI, albuminuria, DCCT randomization, smoking, statin treatment, and ultrasound devices. In cross-sectional analyses, lipoprotein B (Lp-B), Lp-B:C, Lp-B:E+Lp-B:C:E, Apo-A-II, Apo-B, Apo-C-III-HP (heparin precipitate; i.e., Apo-C-III in Apo-B-containing lipoproteins), and Apo-E were positively associated with common and/or internal carotid IMT in men, but only Apo-C-III (total) was (positively) associated with internal carotid IMT in women. In prospective analyses, Lp-B, Apo-B, and Apo-C-III-HP were positively associated with common and/or internal carotid IMT in men, while Lp-A1:AII and Apo-A1 were inversely associated with internal carotid IMT in women. The only significant prospective association between conventional lipids and IMT was between triacylglycerols and internal carotid IMT in men. ADLS and apolipoprotein concentrations may provide sex-specific biomarkers and suggest mechanisms for IMT in people with T1D.

The association between circulating endostatin and a disturbed circadian blood pressure pattern in patients with type 2 diabetes

BACKGROUND

Endostatin, cleaved from collagen XVIII in the extracellular matrix, is a promising circulating biomarker for cardiovascular damage. It possesses anti-angiogenic and anti-fibrotic functions and has even been suggested to be involved in blood pressure regulation. Less is known if endostatin levels relate to circadian blood pressure patterns. In the present paper we studied the association between circulating levels of endostatin and nocturnal dipping in blood pressure.

METHODS

We used the CARDIPP-study, a cohort of middle aged, type 2 diabetics (n = 593, 32% women), with data on both 24-hour and office blood pressure, serum-endostatin, cardiovascular risk factors, and incident major cardiovascular events. Nocturnal dipping was defined as a >10% difference between day- and night-time blood pressures.

RESULTS

Two-hundred four participants (34%) were classified as non-dippers. The mean endostatin levels were significantly higher in non-dippers compared to dippers (mean ± standard deviation: 62.6 ± 1.8 µg/l vs. 58.7 ± 1.6 µg/l, respectively, p = .007). Higher serum levels of endostatin were associated with a diminished decline in nocturnal blood pressure adjusted for age, sex, HbA1c, mean systolic day blood pressure, hypertension treatment, glomerular filtration rate, and prevalent cardiovascular disease (regression coefficient per SD increase of endostatin -0.01, 95% CI, -0.02-(-0.001), p = .03). Structural equation modelling analyses suggest that endostatin mediates 7% of the association between non-dipping and major cardiovascular events.

CONCLUSION

We found an independent association between higher circulating levels of endostatin and a reduced difference between day- and night-time systolic blood pressure in patients with type 2 diabetes. Yet endostatin mediated only a small portion of the association between non-dipping and cardiovascular events arguing against a clinical utility of our findings.

ApoB/ApoA-I ratio is independently associated with carotid atherosclerosis in type 2 diabetes mellitus with well-controlled LDL cholesterol levels

BACKGROUND/AIMS

This study aimed to investigate whether the apolipoprotein (Apo) B/ApoA-I ratio is associated with carotid intima-media thickness (CIMT) in type 2 diabetes mellitus (T2DM) subjects with low density lipoprotein cholesterol (LDL-C) levels less than 100 mg/dL.

METHODS

This cross-sectional study included 845 subjects aged with T2DM 40 to 75 years who had visited Huh's Diabetes Center in Seoul, Republic of Korea for CIMT measurement. Traditional fasting lipid profiles, ApoB and ApoA-I levels were examined. CIMT was measured at three points on the far wall of 1 cm long section of the common carotid artery in the proximity of the carotid bulb. The mean value of six measurements from right and left carotid arteries were used as the mean CIMT. In this study, carotid atherosclerosis was defined as having a focal plaque or diffuse thickening of the carotid wall (mean CIMT ≥ 1.0 mm).

RESULTS

The prevalence of carotid atherosclerosis increased with ApoB/ApoA-I ratio. The ApoB/ApoA-I ratio, expressed as both quartiles (odds ratio [OR], 2.14; 95% confidence interval [CI], 1.21 to 3.79; p for trend = 0.014) and continuous values (OR, 10.05; 95% CI, 3.26 to 30.97; p < 0.001), was significantly associated with a higher risk for carotid atherosclerosis, regardless of conventional cardiovascular disease risk factors. The optimal ApoB/ApoA-I ratio cutoff value for detecting carotid atherosclerosis was 0.57, based on receiver operating characteristic curve analysis with a sensitivity of 58.0% and a specificity of 55.1%.

CONCLUSIONS

A high ApoB/ApoA-I ratio was significantly associated with carotid atherosclerosis in T2DM patients with LDL-C levels less than 100 mg/dL.

Diastolic orthostatic hypertension and cardiovascular prognosis in type 2 diabetes: a prospective cohort study

BACKGROUND

In patients with type 2 diabetes, the prognostic impact of an orthostatic rise in blood pressure is not known. Therefore, the aim of this study was to determine the prognostic implications of the diastolic orthostatic blood pressure response in a cohort of patients with type 2 diabetes. We also evaluated associations between different orthostatic blood pressure responses and markers of subclinical cardiovascular organ damage.

METHODS

Office blood pressures were measured in the sitting and in the standing position in 749 patients with type 2 diabetes who participated in the CARDIPP study (Cardiovascular Risk factors in Patients with Diabetes-a Prospective study in Primary care). Diastolic orthostatic hypertension was defined as a rise of diastolic blood pressure ≥10 mmHg and diastolic orthostatic hypotension was defined as a drop of diastolic blood pressure ≥10 mmHg. Recruitment took place between the years 2005-2008, and patients were followed until any of the primary outcome events (cardiovascular death or hospitalization for either myocardial infarction or stroke) occurred or until December 31st, 2014. Measurements of aortic pulse wave velocity and of carotid intima-media thickness were performed at base-line.

RESULTS

Diastolic orthostatic hypertension was found in 140 patients (18.7 %) and was associated with significantly lower risk of cardiovascular events (crude hazard ratio compared with patients with normal systolic and diastolic orthostatic blood pressure response: 0.450, 95 % C.I. 0.206-0.987, P = 0.046). Diastolic orthostatic hypotension was found in 31 patients (4.1 %) and was associated with higher values for aortic pulse wave velocity and carotid intima-media thickness, compared with patients with normal systolic and diastolic orthostatic blood pressure response.

CONCLUSIONS

Diastolic orthostatic hypertension is common in patients with type 2 diabetes, and may be a novel marker for decreased cardiovascular risk in these patients.

Apolipoprotein-containing lipoprotein subclasses and subclinical atherosclerosis in systemic lupus erythematosus

OBJECTIVE

Traditional classification of hyperlipidemia using high-density lipoprotein, low-density lipoprotein (LDL), and very low-density lipoprotein does not provide information on lipoprotein function. Apolipoproteins (Apos), which are protein components of plasma lipoproteins (including A, B, C, D, E) with their different composition, metabolic, and atherogenic properties, provide insight on lipoprotein functioning. In particular, the Apo B/A-I ratio is associated with atherogenic LDL and development of cardiovascular disease. We explored the baseline association between these nontraditional risk factors with subclinical measures of atherosclerosis (coronary artery calcification [CAC] and carotid intima-media thickness [IMT]) in systemic lupus erythematosus (SLE).

METHODS

A total of 58 SLE patients (97% women, 58% white, 40% African American, and 2% other, mean ± SD age 44 ± 11 years) had measurement of Apo and lipoproteins by immunoturbidimetric procedures, electroimmunoassays, and immunoprecipitation. CAC was measured by helical computed tomography and carotid IMT by carotid duplex. This study was based on the baseline assessment of subclinical atherosclerosis in the Lupus Atherosclerosis Prevention Study. The measurement of the lipoproteins was made on sera collected at the same time.

RESULTS

There was no association between cardioprotective Apos (Apo A-I, LpA-I, LpA-I:A-II) and CAC (P < 0.15, P < 0.41, and P < 0.39, respectively) or carotid IMT (P < 0.97, P < 0.53, and P < 0.76, respectively). CAC and carotid IMT did not associate with atherogenic Apos either, including LpB:E+LpB:C:E, Apo B, LpB, LpB:C, Apo C-III, Apo C-III-HS, Apo C-III-HP, Apo C-III-R, LpA-II:B:C:D:E, and Apo B/Apo A-I. Measures of disease activity, including physician's global assessment and Systemic Lupus Erythematosus Disease Activity Index, were not associated with CAC or carotid IMT.

CONCLUSION

Neither cardioprotective nor atherogenic lipoproteins were associated with measures of subclinical atherosclerosis in this series of SLE patients. Further studies with a larger sample size are warranted to confirm our findings.

The value of the apoB/apoAΙ ratio and the non-HDL-C/HDL-C ratio in predicting carotid atherosclerosis among Chinese individuals with metabolic syndrome: a cross-sectional study

BACKGROUND

Metabolic syndrome (MetS) is associated with carotid intima-media thickness (CIMT), which is a good predictor of cardiovascular disease (CVD). However, among individuals with MetS, direct comparative data regarding the utility of the apoB/apoAΙ ratio and the non-HDL-C/HDL-C ratio to diagnose carotid atherosclerosis are scarce, particularly in Chinese populations. We aimed to determine the relationship between the apoB/apoAΙ ratio and the non-HDL-C/HDL-C ratio and carotid atherosclerosis among Chinese individuals with MetS.

METHODS

We performed a retrospective study of 5822 Chinese participants who underwent a routine health screening examination. Lipid profiles, fasting glucose, fasting insulin, CRP, apoB, apoAΙ and CIMT were measured.

RESULTS

We observed that among Chinese individuals with MetS, men (53.95±0.58 ys) developed carotid atherosclerosis at a younger age than women (58.47±1.17 ys) (P<0.001). Both the apoB/apoAΙ ratio and the non-HDL-C/HDL-C ratio positively correlated with carotid atherosclerosis among Chinese individuals with MetS, particularly among women. Meanwhile, CIMT increased progressively across the quartiles of the non-HDL-C/HDL-C ratio (P for trend, <0.05). Receiver Operating Characteristic (ROC) analysis indicated that the AUC of the apoB/apoAΙ ratio (0.561) was higher than that of the non-HDL-C/HDL-C ratio (0.522) in men (P<0.05) and the AUC of the apoB/apoAΙ ratio (0.640) was lower than that of the non-HDL-C/HDL-C ratio (0.695) in women (P<0.05). Among Chinese individuals with MetS, the AUC of the non-HDL-C/HDL-C ratio was more prominent among women compared with men (P<0.05).

CONCLUSION

Our findings indicate that among individuals with MetS, Chinese men develop carotid atherosclerosis at a much younger age than women. There were no significant differences between the apoB/apoAΙ ratio and the non-HDL-C/HDL-C ratio for the prediction of carotid atherosclerosis among Chinese individuals with MetS. Among Chinese individuals with MetS, the utility of the non-HDL-C/HDL-C ratio was found to be greater among women than among men.

Left ventricular diastolic function, assessed by echocardiography and tissue Doppler imaging, is a strong predictor of cardiovascular events, superior to global left ventricular longitudinal strain, in patients with type 2 diabetes

AIMS

The aim of the study was to determine whether left ventricular systolic function, in terms of global left ventricular longitudinal strain (GLS), and diastolic function, expressed as the ratio between early diastolic transmitral flow and mitral annular motion velocities (E/e'), can predict cardiovascular events in patients with diabetes mellitus type 2.

METHODS AND RESULTS

We prospectively investigated 406 consecutive patients, aged 55-65 years, with diabetes mellitus, who participated in the CARDIPP study. Echocardiography, pulse pressure (pp), and glycosylated haemoglobin (HbA1c) were analysed. Twelve cases of myocardial infarction and seven cases of stroke were identified during the follow-up period of 67 ± 17 months. Univariate Cox regression analysis showed that E/e' was a strong predictor of cardiovascular events (hazards ratio 1.12; 95% confidence interval 1.06-1.18, P < 0.001). E/e' was prospectively associated with cardiovascular events independent of age, sex, GLS, left ventricular ejection fraction (LVEF), pp, and HbA1c in multivariate analysis. Receiver operating characteristic curves showed that E/e' and HbA1c were the strongest predictors for cardiovascular events, both having an area under the curve (AUC) of 0.71 followed by LVEF with an AUC of 0.65 and GLS of 0.61. In a Kaplan-Meyer analysis, the cumulative probability of an event during the follow-up period was 8.6% for patients with an E/e' ratio >15 compared with 2.6% for patients with E/e' ≤15, P = 0.011.

CONCLUSION

In middle-aged patients with type 2 diabetes, E/e' is a strong predictor of myocardial infarction and stroke, comparable with HbA1c and superior to GLS and LVEF.

Association between carotid intima-media thickness and index of central fat distribution in middle-aged and elderly Chinese

Background

Evidence has demonstrated that central fat distribution produces the most profound metabolic abnormalities and is associated with an increased risk of atherosclerotic cardiovascular diseases. We aimed to investigate whether the indexes of central fat distribution, including waist-to-height ratio (WHtR) and visceral fat area (VFA), were stronger risk factors of subclinical atherosclerosis than body mass index (BMI) in Chinese adults.

Methods

A total of 3381 participants aged 40 years or older without history of cardiovascular diseases (CVD) were enrolled in the present cross-sectional study from the Songnan community, Shanghai, China. Height, weight and waist circumference (WC) were measured by experienced physicians. High-resolution B-mode ultrasonography was performed to measure carotid intima-media thickness (CIMT). Regional adiposity was measured by a dual-source computed tomography (CT) scanner.

Results

Normal weight but central obesity group (BMI < 23 kg/m² and WHtR > 0.5) had higher levels of systolic blood pressure (SBP), fasting plasma glucose (FPG), 2 h post-load glucose (2 h PG), Hemoglobin A1c (HbA1c), and CIMT, as well as an elevated prevalence of hypertension and diabetes compared with overweight/obesity but not central obesity group (BMI ≥ 23 kg/m² and WHtR ≤ 0.5). In logistic regression analysis, WHtR > 0.5 was significantly and independently associated with elevated CIMT (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.01-1.68, p value = 0.044). Similar association was noted for each standard deviation (SD) increase of WHtR (OR 1.25, 95% CI 1.07-1.47, p value = 0.006). Stepwise multiple linear regression analysis revealed that both WHtR and VFA were important determinants of CIMT, independent of other well-recognized risk factors (both p values < 0.01).

Conclusions

WHtR and VFA were associated with CIMT, independent of BMI and conventional CVD risk factors. Given the relatively high cost and complexness of VFA measurement, WHtR could be a more convenient and appropriate measure of abdominal obesity in clinical practice.

Association of carotid intima-media thickness with leptin and apoliprotein b/apoliprotein a-I ratio reveals imminent predictors of subclinical atherosclerosis in psoriasis patients

Psoriasis patients are often susceptible to cardiovascular diseases (CVD), including atherosclerosis. Traditional markers (biochemical and inflammatory) and diagnostic tools could detect occlusive but not subclinical atherosclerosis. Carotid intima-media thickness (CIMT), has recently been recognised as a non invasive diagnostic tool for identification of premature atherosclerosis. Therefore we evaluated 80 psoriasis patients and 80 age sex matched healthy controls for serum leptin levels and apolipoprotein B/apolipoprotein A-I ratio (apoB/apoA-I ratio) in relation with CIMT of carotid artery. Carotid intima-media thickness and carotid plaques were simultaneously measured by carotid sonography. Serum concentration of leptin and apolipoprotein were measured using enzyme-linked immuno sorbent assay (ELISA) and nephelometry respectively. Raised CIMT correlated to age of onset of the disease, serum leptin and apoB/apoA-I ratio in psoriasis patients. Taking into account, values that were above the 75 percentile of the three markers (leptin, apoB/apoA-I ratio and CIMT) the odds ratio was 4.26 (2.06-8.80 CI). Leptin and apoB/apoA-I ratio showed significant cumulative association with CIMT. Results of predictive analysis supports measurement of CIMT along with estimation of serum leptin and apoB/apoA-I ratio for prediction of premature atherosclerosis in psoriasis patients.

Increased carotid intima media thickness is associated with prolactin levels in subjects with untreated prolactinoma: a pilot study

Hyperprolactinemia is associated with endothelial dysfunction and atherogenic risk factors, but carotid intima media thickness (IMT) has not been studied in hyperprolactinemic patients. To determine whether untreated hyperprolactinemia contributes to increased carotid IMT. Thirty-one prolactinoma patients and 60 healthy controls were respectively studied. Participants underwent hormone evaluation. Anthropometric parameters (body mass index and blood pressure), inflammatory markers (high-sensitivity C-reactive protein and fibrinogen), serum glucose, insulin, lipid and apolipoprotein profiles were also determined. Endothelial function measured as the flow-mediated dilation (FMD) of a brachial artery and carotid IMT were evaluated using high-resolution ultrasonography. Multivariate linear regression analysis was applied to identify independent determinants of FMD and carotid IMT. Triglycerides, homeostasis model assessment of insulin resistance, apolipoprotein (apo)B/apoA-I ratio, high-sensitivity C-reactive protein (hsCRP) and fibrinogen were significantly higher, while apoA-I was significantly lower in patients with prolactinomas than in the controls. Meanwhile, decreased FMD and increased carotid IMT were observed in hyperprolactinemic group. Serum prolactin was positively correlated with triglycerides, apoB/apoA-I ratio, hypogonadal, hsCRP and fibrinogen (P < 0.05), but inversely associated with apoA-I and HDL-C (P ≤ 0.001). Moreover, prolactin was found negatively correlated with FMD (r = -0.576, P < 0.0001), and positively correlated with mean carotid IMT (r = 0.652, P < 0.0001). Multivariate regression analysis revealed that prolactin determined, independent of traditional risk factors, FMD (B = -0.589, 95% confidence interval (CI) -2.525 to -0.804, P = 0.001) and mean carotid IMT (B = 0.527, 95% CI 0.027-0.069, P < 0.0001). Hyperprolactinemia may be involved in the preclinical increase in carotid IMT, directly or by promoting atherogenic factors, including insulin resistance, low-grade inflammation and endothelial dysfunction. Additional studies are warranted to confirm our findings and explore the mechanisms underlying prolactin-associated early atherosclerosis.

Abdominal obesity and low-grade systemic inflammation as markers of subclinical organ damage in type 2 diabetes

AIM

This study aimed to explore the associations between abdominal obesity, inflammatory markers and subclinical organ damage in 740 middle-aged patients with type 2 diabetes.

METHODS

Waist circumference (WC) and sagittal abdominal diameter (SAD) were measured, and blood samples were analyzed for C-reactive protein (CRP) and IL-6. Carotid intima-media thickness (IMT) was evaluated by ultrasonography, and aortic pulse wave velocity (PWV) measured with applanation tonometry.

RESULTS

Abdominal obesity as determined by SAD and WC was significantly correlated with IL-6 (WC: r=0.27, P<0.001; SAD: r=031, P<0.001), CRP (WC: r=0.29, P<0.001; SAD: r=0.29, P<0.001), IMT (WC: r=0.09, P=0.013; SAD: r=0.11, P=0.003) and PWV (WC: r=0.18, P<0.001; SAD: r=0.21, P<0.001). In multiple linear regressions with IMT and PWV as dependent variables, and age, gender, statin use, systolic blood pressure (SBP), body mass index (BMI), CRP and HbA1c as independent variables, both SAD and WC remained associated with IMT and PWV. On stepwise linear regression and entering both SAD and WC, the association between SAD and PWV was stronger than the association between WC and PWV.

CONCLUSION

Both SAD and WC are feasible measures of obesity, and both provide information on inflammation, atherosclerosis and arterial stiffness in type 2 diabetes, while SAD appears to be slightly more robustly associated with subclinical organ damage than WC.

Toe brachial index in middle aged patients with diabetes mellitus type 2: not just a peripheral issue

AIM

To explore risk factors for peripheral arterial disease (PAD) as well as the association between toe blood pressure and subclinical and clinical central vascular disease in patients with type 2 diabetes.

METHOD

Toe brachial index (TBI) was cross-sectionally analyzed in 742 middle-aged (54-66 years) patients with type 2 diabetes as well as non-diabetic controls and related to other vascular measures (e.g. carotid intima media thickness (IMT), presence of carotid plaque, central arterial stiffness and left ventricular mass index) and previous cardiovascular events.

RESULTS

A TBI ≤ 0.7 was seen in 22% of the patients but only one patient had severe TBI reduction (TBI ≤ 0.3). The corresponding figures in the controls were 13% and 0%, respectively. Mean TBI was significantly lower in patients with type 2 diabetes than in controls (0.81 ± 0.14 vs. 0.87 ± 0.15, p<0.001). In patients with diabetes, a lower TBI was associated with increased central arterial stiffness (p<0.001), IMT (p<0.001) and carotid plaque (p<0.001) as well as with decreasing glomerular filtration rate (p<0.001). Lower TBI was found in patients with previous macrovascular ischemic events. Furthermore, TBI was negatively correlated with age (p<0.001), diabetes duration (p<0.001) and HbA1c (p=0.01).

CONCLUSION

PAD, assessed with TBI, is common in a Swedish middle-aged diabetes type 2 cohort, affecting about one-fifth. As ankle pressure may be confounded by falsely high values in patients with diabetes due to media calcification we conclude that information about TBI may improve the risk evaluation regarding arteriosclerotic disease in both small and large vessels in type 2 diabetes.

Sagittal abdominal diameter is a more independent measure compared with waist circumference to predict arterial stiffness in subjects with type 2 diabetes--a prospective observational cohort study

Background

Anthropometric measurements are useful in clinical practice since they are non-invasive and cheap. Previous studies suggest that sagittal abdominal diameter (SAD) may be a better measure of visceral fat depots. The aim of this study was to prospectively explore and compare how laboratory and anthropometric risk markers predicted subclinical organ damage in 255 patients, with type 2 diabetes, after four years.

Methods

Baseline investigations were performed in 2006 and were repeated at follow-up in 2010. Carotid intima-media thickness (IMT) was evaluated by ultrasonography and aortic pulse wave velocity (PWV) was measured with applanation tonometry over the carotid and femoral arteries at baseline and at follow-up in a cohort of subjects with type 2 diabetes aged 55–65 years old.

Results

There were significant correlations between apolipoprotein B (apoB) (r = 0.144, p = 0.03), C - reactive protein (CRP) (r = 0.172, p = 0.009) at baseline and IMT measured at follow-up. After adjustment for sex, age, treatment with statins and Hba1c, the associations remained statistically significant. HbA1c, total cholesterol or LDL-cholesterol did not correlate to IMT at follow-up. Baseline body mass index (BMI) (r = 0.130, p = 0.049), waist circumference (WC) (r = 0.147, p = 0.027) and sagittal Abdominal Diameter (SAD) (r = 0.184, p = 0.007) correlated to PWV at follow-up. Challenged with sex, SBP and HbA1c, the association between SAD, not WC nor BMI, and PWV remained statistically significant (p = 0.036). In a stepwise linear regression, entering both SAD and WC, the association between SAD and PWV was stronger than the association between WC and PWV.

Conclusions

We conclude that apoB and CRP, but not LDL-cholesterol predicted subclinical atherosclerosis. Furthermore, SAD was more independent in predicting arterial stiffness over time, compared with WC, in middle-aged men and women with type 2 diabetes.

Temporal changes in concentrations of lipids and apolipoprotein B among adults with diagnosed and undiagnosed diabetes, prediabetes, and normoglycemia: findings from the National Health and Nutrition Examination Survey 1988-1991 to 2005-2008

Background

Diabetes is characterized by profound lipid abnormalities. The objective of this study was to examine changes in concentrations of lipids and apolipoprotein B among participants stratified by glycemic status (diabetes, undiagnosed diabetes, prediabetes, and normoglycemia) in the United States from 1988–1991 to 2005–2008.

Methods

We used data from 3202 participants aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES) III (1988–1991) and 3949 participants aged ≥20 years from NHANES 2005–2008.

Results

Among participants of all four groups, unadjusted and adjusted mean concentrations of total cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and apolipoprotein B, but not triglycerides, decreased significantly. Among participants with prediabetes and normoglycemia, unadjusted and adjusted mean concentrations of high-density lipoprotein cholesterol increased significantly. Adjusted mean log-transformed concentrations of triglycerides decreased in adults with undiagnosed diabetes and prediabetes. During 2005–2008, unadjusted concentrations of apolipoprotein B ≥80 mg/dl were observed in 72.8% of participants with diagnosed diabetes, 87.9% of participants with undiagnosed diabetes, 86.6% of participants with prediabetes, and 77.2% of participants with normoglycemia. The unadjusted use of cholesterol-lowering medications rose rapidly, especially among participants with diabetes (from ~1% to ~49%, P <0.001). The use of fenofibrate, gemfibrozil, and niacin rose significantly only among adults with diagnosed diabetes (from ~2% to ~8%, P = 0.011).

Conclusion

Lipid profiles of adults with diabetes improved during the approximately 16-year study period. Nevertheless, large percentages of adults continue to have elevated concentrations of apolipoprotein B.

Associations of genetic polymorphisms in the renin-angiotensin system with central aortic and ambulatory blood pressure in type 2 diabetic patients

Patients with type 2 diabetes (T2D) are at high risk of developing hypertension and related cardiovascular disease. The renin-angiotensin system (RAS) plays a central role in regulation of blood pressure (BP). Accordingly, each component of this system represents a potential candidate in the etiology of hypertension. This study investigated the impact of polymorphisms within the RAS on ambulatory and central BP in T2D subjects. A cohort of 761 subjects (55-65 years) with T2D was studied. Ambulatory and central BP were measured, and ACE I/D genotype, angiotensinogen M235T, renin rs6693954 and ATR1-A1166C polymorphisms were analyzed. Women carrying the AA-genotype had lower 24-hour and day-time systolic and diastolic BP (p<0.05), and lower night-time and central diastolic BP (p<0.05), compared to T allele carriers. In men, the AA-genotype was instead associated with higher central diastolic BP (p=0.018) and higher augmentation index (p=0.016). Further, the associations between the renin rs6693954 SNP and diastolic BP were strongly gender dependent (p≤0.001). In T2D patients, there is a gender-dependent association of the renin rs6693954 SNP with central and ambulatory BP. Women carrying the renin rs6693954 AA-genotype may be protected against the higher BP seen in men with the same genotype.

BMI, apolipoprotein B/apolipoprotein A-I ratio, and insulin resistance in patients with prolactinomas: a pilot study in a Chinese cohort

Deranged metabolic profiles and insulin resistance (IR) have been documented in patients with prolactinomas. Few data are yet available on the apolipoprotein (apo) B/apoA-I ratio and its relationship with IR in patients with prolactinomas. This study was aimed to evaluate the level of apoB/apoA-I ratio and its association with IR in a Chinese subgroup with prolactinomas. Twenty-three prolactinoma patients and 20 healthy controls were enrolled in this study. The clinical anthropometric parameters and laboratory evaluation were collected. Insulin sensitivity was estimated using homeostatic model assessment [homeostasis model assessment of insulin resistance (HOMA-IR)]. Waist circumference and body weight index (BMI) were significantly higher in patients with prolactinomas than those in the controls (p < 0.05). Meanwhile, the prevalence of general and abdominal obesity seemed more pronounced in male patients compared to that in healthy subjects (57.14 vs. 0 % and 71.43 vs. 16.7 %, respectively). Furthermore, fasting glucose, insulin, HOMA-IR, triglyceride, and apoB/apoA-I ratio were also significantly higher in prolactinoma patients, but with lower level of apoA-I (p < 0.05). Univariate regression analysis revealed that prolactin, waist circumference, BMI, and presence of hypogonadism were significantly associated with IR (p < 0.05). However, only BMI [odds ratio (OR) = 1.937, 95 % confidence interval (CI) 1.112-3.375, p = 0.02] and prolactin (OR = 5.173, 95 % CI 1.073-24.94, p = 0.041) were shown to be independent predictors for the presence of IR in multivariate logistic analysis. This study confirmed the altered metabolic profile, including body weight gain, IR, disordered lipids, and apolipoproteins in prolactinoma patients. Prolactin and BMI were independently associated with IR. The effect of apoB/apoA-I ratio on IR is warranted to be determined in further studies.

Both serum apolipoprotein B and the apolipoprotein B/apolipoprotein A-I ratio are associated with carotid intima-media thickness

Background

Previous studies indicated that apolipoprotein measurements predicted cardiovascular disease (CVD) risk; however, associations between apolipoproteins and carotid intima-media thickness (CIMT) were less explored.

Methodology and Principal Findings

The cross-sectional study included 6069 participants aged 40 years or older with NGT from Shanghai, China. Serum fasting traditional lipids (total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C] and triglycerides [TG]), apoA-I and apoB were assessed. A high-resolution B-mode ultrasonography was performed to measure CIMT. We found CIMT increased progressively across the quartiles of serum apoB (p for trend <0.0001). In logistic regression, concentrations of apoB (odds ratio [OR] 1.27, 95% confidence interval [CI] 1.18–1.36), TC (OR 1.23, 95% CI 1.14–1.32), LDL-C (OR 1.25, 95% CI 1.16–1.34) and TG (OR 1.11, 95% CI 1.04–1.20) were significantly related to elevated CIMT after adjusted for age and sex. Meanwhile, the apoB/apoA-I ratio (OR 1.25, 95% CI 1.17–1.34) related to elevated CIMT. ApoB (OR 1.23, 95% CI 1.00–1.51) and the apoB/apoA-I ratio (OR 1.19, 95% CI 1.04–1.36) remained significantly associated with elevated CIMT, after adjusted for the traditional CVD risk factors including traditional lipids.

Conclusions and Significance

There were significant associations between serum apoB, the apoB/apoA-I ratio and elevated CIMT. Serum apoB and the apoB/apoA-I ratio might be independent predictors of early atherosclerosis in NGT.

Association of the apolipoprotein B/apolipoprotein A-I ratio and low-density lipoprotein cholesterol with insulin resistance in a Chinese population with abdominal obesity

The aim of this study is to assess the relationships among the apolipoprotein B/apolipoprotein A-I ratio (apoB/apoA-I ratio), low-density lipoprotein cholesterol (LDL-C) and insulin resistance (IR) in a Chinese population with abdominal obesity. This is a population-based, cross-sectional study of 3,945 men and 2,141 women with abdominal obesity. Individuals were referred to a primary health service and recruited for analysis. IR was measured using a homeostasis model assessment of insulin resistance (HOMA2-IR) with a HOMA2 calculator. Metabolic syndrome (MetS) was diagnosed using International Diabetes Federation (IDF) criteria. Comparing the apoB/apoA-I ratio and lipid indices using the HOMA2-IR showed that the ratio, LDL-C, total cholesterol level (TC) and triglyceride level (TG) were higher; and the high-density lipoprotein cholesterol level (HDL-C) was lower in the fourth than in the first quartile in both sexes (p ≤ 0.001). After adjustment for age, HOMA2-IR was positively correlated with the apoB/apoA-I ratio, LDL-C, TC and TG; and negatively correlated with HDL-C in men (all p < 0.0001). HOMA2-IR was also positively correlated with the apoB/apoA-I ratio, LDL-C, TC and TG; and negatively correlated with HDL-C in women (all p < 0.01). After adjustment for age and LDL-C, HOMA2-IR was found to be correlated with the apoB/apoA-I ratio in both men and women (r = 0.066 and 0.116, p < 0.0001). After adjustment for age and the apoB/apoA-I ratio, HOMA2-IR was correlated with LDL-C in men and women (r = 0.063 and 0.044, p < 0.0001 and p = 0.0431, respectively). Gender, age, LDL-C, BMI, HOMA2-IR and apoB/apoA-I were the covariates independently associated with presence of the MetS (Odds ratio, OR: 2.183, 1.034, 1.013, 1.157, 1.726 and 1.570, respectively; all p < 0.05). In conclusion, the study showed that the apoB/apoA-I ratio and LDL-C were positively correlated with IR. Excluding reciprocal interactions, the apoB/apoA-I ratio and LDL-C were still significantly correlated with IR, but the apoB/apoA-I ratio showed a greater correlation with IR than LDL-C in women with abdominal obesity, compared with men with abdominal obesity. Both LDL-C and apoB/apoA-I were independent risk factors of MetS, and the apoB/apoA-I ratio was stronger in this regard than LDL-C for this obese population.

Predictors of the intima-media thickness of carotid artery in asymptomatic newly detected severe hypercholesterolemic patients

BACKGROUND

Data about predictors of intima-media thickness (IMT) of common carotid artery (CCA) in asymptomatic subjects with newly detected severe hypercholesterolemia is scarce.

AIM

This research is aimed at studying the predictors of the IMT of CCA among basic atherogenic risk biomarkers - lipid [total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein (LDL) cholesterol, Apolipoprotein-B, Apolipoprotein-Ai, Apolipoprotein-B/A(1) index] and non-lipid, [asymmetric dimethylarginine (ADMA), total homocysteine, cell adhesion molecules] in asymptomatic subjects with newly detected severe hypercholesterolemia.

METHODS

Two hundred and fifty asymptomatic patients with severe, newly hypercholesterolemia and 200 controls were evaluated. Hypercholesterolemia was defined as TC > 7.5 mm and LDL cholesterol > 4.9 mm. The ADMA and cell adhesion molecules were determined by ELISA and total homocysteine by high-performance liquid chromatography.

RESULTS

There was significant difference between the two groups in respect to all lipid biomarkers (P<0.001). Hypercholesterolemic patients had significantly higher level of ADMA, sVCAM-1, sICAM-1, IMT (P<0.001), whereas no significant difference was found between two groups with respect to total homocysteine, P-selectin and E-selectin (P>0.05). A strong positive correlation between IMT mean and age (r(xy) = 0.714; P<0.001), Apolipoprotein-B (r(xy) = 0.706; r(xy) < 0.001), Apolipoprotein-B/A(1) (r(xy) = 0.324; P<0.001), ADMA (r(xy) = 0.603; P<0.001) was found. The subsequent linear and multiple regression analysis selected age and Apolipoprotein-B as most significant factors in relation to IMT mean. Apolipoprotein-B is a better factor for assessment of risk, as LDL cholesterol underestimates the risk in asymptomatic subjects with newly detected severe hypercholesterolemia, until more rapid and feasible methods for measurement of small and dense LDL are available.

Usefulness of lipoprotein ratios in assessing carotid atherosclerosis in Japanese type 2 diabetic patients

OBJECTIVE

It is indicated that total/HDL cholesterol and LDL/HDL cholesterol ratios have more predictive power for cardiovascular disease compared to classic lipid parameters. However, there have been few reports about the usefulness of these indices for the assessment of early stage atherosclerosis in Japanese type 2 diabetic subjects.

METHODS

We examined the relation between various lipid parameters and carotid atherosclerosis in 934 type 2 diabetic subjects without apparent atherosclerotic diseases (males, 71.7%; age, 59.6 ± 10.5 years (mean ± SD)). Serum concentrations of total cholesterol (TC), HDL cholesterol (HDL-C), and triglyceride were measured. LDL cholesterol (LDL-C) level was calculated using the Friedewald formula. The presence of carotid plaque and intima-media thickness (IMT) were evaluated by ultrasonography.

RESULTS

A stepwise multivariate regression analysis demonstrated that HDL-C (β = -0.110, p<0.001), TC/HDL-C (β = 0.132, p < 0.001) and LDL-C/HDL-C ratios (β = 0.132, p < 0.001) were independent determinants of IMT even after adjustment of other conventional risk factors. However, there was no significant correlation between IMT and TC, triglyceride, LDL-C, and non-HDL-C levels. TC/HDL-C and LDL-C/HDL-C ratios and non-HDL-C levels were significantly higher, but HDL-C levels were significantly lower in patients with carotid plaque than those without it (p < 0.05). There was no significant difference between the groups regarding TC, LDL-C, and triglyceride levels. Furthermore, TC/HDL-C (OR; 1.34, p < 0.001) and LDL-C/HDL-C (OR; 1.54, p < 0.001) ratios showed a positive and linear relationship with the prevalence of carotid plaque, whether covariates were adjusted or not.

CONCLUSIONS

TC/HDL-C and LDL-C/HDL-C ratios are useful as a tool to assess the risk of early stage atherosclerosis in Japanese type 2 diabetic patients.

Reduced arteriovenous shunting capacity after local heating and redistribution of baseline skin blood flow in type 2 diabetes assessed with velocity-resolved quantitative laser Doppler flowmetry

OBJECTIVE

To compare the microcirculatory velocity distribution in type 2 diabetic patients and nondiabetic control subjects at baseline and after local heating.

RESEARCH DESIGN AND METHODS

The skin blood flow response to local heating (44 degrees C for 20 min) was assessed in 28 diabetic patients and 29 control subjects using a new velocity-resolved quantitative laser Doppler flowmetry technique (qLDF). The qLDF estimates erythrocyte (RBC) perfusion (velocity x concentration), in a physiologically relevant unit (grams RBC per 100 g tissue x millimeters per second) in a fixed output volume, separated into three velocity regions: v <1 mm/s, v 1-10 mm/s, and v >10 mm/s.

RESULTS

The increased blood flow occurs in vessels with a velocity >1 mm/s. A significantly lower response in qLDF total perfusion was found in diabetic patients than in control subjects after heat provocation because of less high-velocity blood flow (v >10 mm/s). The RBC concentration in diabetic patients increased sevenfold for v between 1 and 10 mm/s, and 15-fold for v >10 mm/s, whereas no significant increase was found for v <1 mm/s. The mean velocity increased from 0.94 to 7.3 mm/s in diabetic patients and from 0.83 to 9.7 mm/s in control subjects.

CONCLUSIONS

The perfusion increase occurs in larger shunting vessels and not as an increase in capillary flow. Baseline diabetic patient data indicated a redistribution of flow to higher velocity regions, associated with longer duration of diabetes. A lower perfusion was associated with a higher BMI and a lower toe-to-brachial systolic blood pressure ratio.