Obesity, metabolic syndrome, impaired fasting glucose, and microvascular dysfunction: a principal component analysis approach

Diogo G Panazzolo,Fernando L Sicuro,Luiz G Kraemer-Aguiar,Ruth Clapauch,Eliete Bouskela,Priscila A Maranhão

doi:10.1186/1471-2261-12-102

Diogo G Panazzolo, Fernando L Sicuro + Show 4 more

Open Access

https://doi.org/10.1186/1471-2261-12-102

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Abstract

BackgroundWe aimed to evaluate the multivariate association between functional microvascular variables and clinical-laboratorial-anthropometrical measurements.MethodsData from 189 female subjects (34.0±15.5 years, 30.5±7.1 kg/m2), who were non-smokers, non-regular drug users, without a history of diabetes and/or hypertension, were analyzed by principal component analysis (PCA). PCA is a classical multivariate exploratory tool because it highlights common variation between variables allowing inferences about possible biological meaning of associations between them, without pre-establishing cause-effect relationships. In total, 15 variables were used for PCA: body mass index (BMI), waist circumference, systolic and diastolic blood pressure (BP), fasting plasma glucose, levels of total cholesterol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triglycerides (TG), insulin, C-reactive protein (CRP), and functional microvascular variables measured by nailfold videocapillaroscopy. Nailfold videocapillaroscopy was used for direct visualization of nutritive capillaries, assessing functional capillary density, red blood cell velocity (RBCV) at rest and peak after 1 min of arterial occlusion (RBCVmax), and the time taken to reach RBCVmax (TRBCVmax).ResultsA total of 35% of subjects had metabolic syndrome, 77% were overweight/obese, and 9.5% had impaired fasting glucose. PCA was able to recognize that functional microvascular variables and clinical-laboratorial-anthropometrical measurements had a similar variation. The first five principal components explained most of the intrinsic variation of the data. For example, principal component 1 was associated with BMI, waist circumference, systolic BP, diastolic BP, insulin, TG, CRP, and TRBCVmax varying in the same way. Principal component 1 also showed a strong association among HDL-c, RBCV, and RBCVmax, but in the opposite way. Principal component 3 was associated only with microvascular variables in the same way (functional capillary density, RBCV and RBCVmax). Fasting plasma glucose appeared to be related to principal component 4 and did not show any association with microvascular reactivity.ConclusionsIn non-diabetic female subjects, a multivariate scenario of associations between classic clinical variables strictly related to obesity and metabolic syndrome suggests a significant relationship between these diseases and microvascular reactivity.

Highlights

We aimed to evaluate the multivariate association between functional microvascular variables and clinical-laboratorial-anthropometrical measurements
That in response to an insulin-sensitizing agent given to metabolic syndrome normoglycemic patients, there was a concomitant improvement in skin microvascular dysfunction [15] and in endothelial microvascular reactivity in the muscle [16]
Metabolic syndrome was diagnosed according to age as follows: 36% (n=13) of subjects were ≤18 years (19% [n=36]); 32% (n=22) of subjects were between 19–30 years (36% [n=68]); 50% (n=20) of subjects were between 31–50 years (21% [n=40]); and 24% (n=11) of subjects were ≥51 years (24% [n=45])

Summary

Introduction

We aimed to evaluate the multivariate association between functional microvascular variables and clinical-laboratorial-anthropometrical measurements. 15 variables were used for PCA: body mass index (BMI), waist circumference, systolic and diastolic blood pressure (BP), fasting plasma glucose, levels of total cholesterol, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), triglycerides (TG), insulin, C-reactive protein (CRP), and functional microvascular variables measured by nailfold videocapillaroscopy. Several techniques have been proposed and used to assess microvascular reactivity in the microcirculation Among these techniques, nailfold videocapillaroscopy is a non-invasive technique that visualizes capillaries, assessing skin nutritive microvascular flow and reactivity. Many studies of small sample sizes have documented that skin capillary recruitment, an index of healthy tissue status, is related to insulin resistance and blood pressure (BP), even in normotensive [3] and obese subjects [4,5]. The concept of microvascular dysfunction as the pathophysiological basis of a pre-receptor defect aggravating insulin resistance and its cause-effect relationship is still a matter of debate [8]

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