Albuminuria Is Associated With Early Carotid Atherosclerosis
Albuminuria Is Associated With Early Carotid Atherosclerosis
We used the data from our previous study, which aimed to determine the prevalence of diabetic complications in Chinese patients in downtown Shanghai who were diagnosed with type 2 diabetes in 2004. Briefly, 1039 Chinese patients aged over 30 who were diagnosed with type 2 diabetes were enrolled in the present study. These patients were from twenty residential areas randomly selected from two of downtown Shanghai's urban areas. Of these, we excluded 564 participants for the following reasons: lack of physical examination and laboratory assessments (21 cases), the presence of kidney disease or other diseases contributing to proteinuria, such as systemic lupus erythematosus (12 cases), 2 of 3 UACR measurements greater than 3.5 mg/mmol (492 cases), and lack of carotid ultrasonography data (39 cases). Four hundred seventy-five subjects, including 190 males and 285 females, were included in the final analysis. The present study was approved by the Ethics Committee of HuaShan Hospital, and written consent was obtained from all participants.
The physical and laboratory examinations used in this study have been described previously. The glomerular filtration rate (GFR) was estimated based on serum creatinine concentration using the simplified MDRD formula: estimated GFR (eGFR) = 186.3× (Serum creatinine)× (age)(×0.742 if female). The urinary albumin excretion rate was determined as the mean of three separate early morning urine samples obtained over a period of 3 months. UACR was calculated from urinary albumin divided by urinary creatinine based on the screening protocol of the American Diabetes Association; 2 of 3 urinary albumin-creatinine ratios less than 3.5 mg/mmol within a period of 3 months were categorized as normoalbuminuria.
Carotid ultrasonography was performed using a machine with a phased-array transducer (Acuson Sequoia 512, Siemens) and was conducted by certified, proficient sonographers. The ultrasound scanning protocol used in the present study was modified from procedures used in previous studies. That is, the sonographers successively recorded and read bilateral images of the common carotid arteries (1 cm proximal to the dilatation of the carotid bulb), the carotid bulb (identified by the loss of the parallel wall present in the common carotid artery), and the internal carotid artery (1 cm distal to the tip of the flow divider that separates the external and internal carotid arteries). The intima-media thickness was the distance between the lumen-intima interface and the media-adventitia interface. CIMT was defined as the mean of the right and left IMTs of the common carotid artery. Plaque within the carotid artery was defined as a localized protrusion of the internal part of the vessel wall into the lumen of 50% of the surrounding IMT value. Carotid stenosis was defined as any degree of narrowing of the carotid arteries by carotid plaques.
The data were analyzed using SPSS 15.0 software. For continuous variables, normality was checked. If the data conformed to a normal distribution, variables were given as the mean ± S.D. and one-way ANOVA with LSD was used to determine differences among groups. If the data were not distributed normally, the Kruskal-Wallis test was employed and variables were expressed as the median. Categorical variables were represented either as absolute numbers or as percentages. Chi-squared statistical analysis was utilized to determine differences in categorical variables. Both stepwise forward multiple linear regression and binary logistic regression analyses were performed to examine the association between UACR tertiles and carotid atherosclerotic lesions and to assess the correlations of three parameters of carotid lesions with each other. P <0.05 (two-sided) was considered to be statistically significant.
Materials and Methods
Subjects and Study Design
We used the data from our previous study, which aimed to determine the prevalence of diabetic complications in Chinese patients in downtown Shanghai who were diagnosed with type 2 diabetes in 2004. Briefly, 1039 Chinese patients aged over 30 who were diagnosed with type 2 diabetes were enrolled in the present study. These patients were from twenty residential areas randomly selected from two of downtown Shanghai's urban areas. Of these, we excluded 564 participants for the following reasons: lack of physical examination and laboratory assessments (21 cases), the presence of kidney disease or other diseases contributing to proteinuria, such as systemic lupus erythematosus (12 cases), 2 of 3 UACR measurements greater than 3.5 mg/mmol (492 cases), and lack of carotid ultrasonography data (39 cases). Four hundred seventy-five subjects, including 190 males and 285 females, were included in the final analysis. The present study was approved by the Ethics Committee of HuaShan Hospital, and written consent was obtained from all participants.
Physical Examination and Laboratory Measurements
The physical and laboratory examinations used in this study have been described previously. The glomerular filtration rate (GFR) was estimated based on serum creatinine concentration using the simplified MDRD formula: estimated GFR (eGFR) = 186.3× (Serum creatinine)× (age)(×0.742 if female). The urinary albumin excretion rate was determined as the mean of three separate early morning urine samples obtained over a period of 3 months. UACR was calculated from urinary albumin divided by urinary creatinine based on the screening protocol of the American Diabetes Association; 2 of 3 urinary albumin-creatinine ratios less than 3.5 mg/mmol within a period of 3 months were categorized as normoalbuminuria.
Ultrasonography Measurements
Carotid ultrasonography was performed using a machine with a phased-array transducer (Acuson Sequoia 512, Siemens) and was conducted by certified, proficient sonographers. The ultrasound scanning protocol used in the present study was modified from procedures used in previous studies. That is, the sonographers successively recorded and read bilateral images of the common carotid arteries (1 cm proximal to the dilatation of the carotid bulb), the carotid bulb (identified by the loss of the parallel wall present in the common carotid artery), and the internal carotid artery (1 cm distal to the tip of the flow divider that separates the external and internal carotid arteries). The intima-media thickness was the distance between the lumen-intima interface and the media-adventitia interface. CIMT was defined as the mean of the right and left IMTs of the common carotid artery. Plaque within the carotid artery was defined as a localized protrusion of the internal part of the vessel wall into the lumen of 50% of the surrounding IMT value. Carotid stenosis was defined as any degree of narrowing of the carotid arteries by carotid plaques.
Statistical Analyses
The data were analyzed using SPSS 15.0 software. For continuous variables, normality was checked. If the data conformed to a normal distribution, variables were given as the mean ± S.D. and one-way ANOVA with LSD was used to determine differences among groups. If the data were not distributed normally, the Kruskal-Wallis test was employed and variables were expressed as the median. Categorical variables were represented either as absolute numbers or as percentages. Chi-squared statistical analysis was utilized to determine differences in categorical variables. Both stepwise forward multiple linear regression and binary logistic regression analyses were performed to examine the association between UACR tertiles and carotid atherosclerotic lesions and to assess the correlations of three parameters of carotid lesions with each other. P <0.05 (two-sided) was considered to be statistically significant.
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