【摘要】 目的：研究血脂分析结果与糖尿病性视网膜病之间的关系，以及2型糖尿患者合并其他系统疾病之间氧化低密度脂蛋白的关系。方法：横断面研究，包括40位糖尿病并糖尿病性视网膜病患者和40位糖尿病不并有糖尿病性视网膜病患者。收集人口学资料，进行详细眼科检查。空腹采集9mL静脉血，分析血清胆固醇，甘油三酯，高密度脂蛋白，低密度脂蛋白，氧化低密度脂蛋白和糖化血红蛋白。结果：糖尿病性视网膜病组平均血清胆固醇为5.9±1.86mmol/L，非糖尿病性视网膜病组为5.0±1.03mmol/L(P=0.001)。糖尿病性视网膜病组血清低密度脂蛋白为3.6±1.69mmol/L，而对照组为3.0±1.02mmol/L(P=0.005)。与轻至中度视网膜硬性渗出患者比较，重度视网膜硬性渗出患者血清胆固醇，甘油三酯和低密度脂蛋白较高，但是差异无统计学意义(P=0.082, 0.116, 0.218)。重度硬性渗出患者的平均血清氧化低密度脂蛋白较轻至中度者高。糖尿病病史长短以及是否合并其他系统疾病之间平均氧化低密度脂蛋白无统计学显著性差异。结论：血清胆固醇和低密度脂蛋白与糖尿病性视网膜病显著相关，而血清血脂分析结果与视网膜硬性渗出严重度不相关。我们研究发现，血清氧化低密度脂蛋白与糖尿病性视网膜病及合并的其他系统疾病之间无相关关系。
【关键词】 视网膜硬性渗出 血脂分析 2型糖尿病
INTRODUCTION
Diabetic retinopathy(DR) is the leading cause of blindness among persons aged 2064 years in the US[1]. The prevelance of DR in Asian India population varies from 4%16%[2]. In Malaysia about 30% of the diagnosed diabetic population has DR[3].
Studies showed significant association between serum lipids and increased severity of retinal hard exudates in DR[4]. The elevation of blood viscosity and alterations in the fibrinolytic system occurs in hyperlipidemia causing hard exudate formation[5]. A direct toxic effect of LDL on retinal capillary pericytes has been demonstrated, and this toxic effect can be enhanced by LDL glycation or oxidation[6,7]. Accumulation of retinal hard exudates can lead to vision loss either from a foveal lipid plaque or from the development of fibrosis[8]. Our objectives are to compare the mean serum lipid profile in patients with DR and no DR, to determine the association between mean serum lipid profile and retinal hard exudate in DR group, and to determine the association between serum oxidizedLDL with DR and other systemic comorbidity.
MATERIALS AND METHODS
Subjects A cross sectional study was conducted from 20062008, in Ophthalmic Clinic in Hospital Universiti Sains Malaysia(HUSM). Our sample size was calculated by using two means or two proportions, independent observation, with confedence interval of 95%, 80% power of study, and the significance ≤ 0.05.The sample size was 80 patients, 40 type 2 diabetes mellitus(DM) with DR (Group A) 40 type 2 DM with no DR (Group B). This study was approved by Ethics & Research Committee of USM. The selection criteria: We include all diagnosed DM type II patients, and we exclude patients on contraceptive pills and thiazide antihypertensive drugs, pregnancy, hypothyroidism, obstructive liver disease, chronic renal failure or nephrotic syndrome, whereby, patients with opaque media obscuring the good visualization of fundus were also excluded. Patients were selected based on inclusion and exclusion criteria. Selected patients were informed and explained regarding the study by the investigator. They were enrolled in the study after written informed consent was obtained.
Methods The demograhic data was taken from the patients. Examination of fundus was performed using a slit lamp and indirect contact lens +90D or +78D and fundus photography was taken. If the two eyes had unequal distribution of retinal hard exudates(RHE) the more affected eye was selected. If only one eye had DR the affected eye was selected. If patient has one eye with opaque media and the other eye with clear media the eye with clear media was selected. Fasting venous blood was taken for serum cholesterol, triglycerides, HDL and LDL, oxidizedLDL and HbA1C.
The grading of RHE was modefied from the International Clinical Diabetic Macular Edema[9]. Disease Severity Scale. Grade I (mild): RHE in the posterior pole but distant from the center of the macula (Figure 1A). Grade II (Moderate) RHE approaching the center of the macula but not involving the center (Figure 1B). Grade III (severe): RHE involving the center of the macula (Figure 1C).
Statistical Analysis Data were analyzed using SPSS version 12.01 (2003). Descriptive analysis were used for the mean values and SD. All values were tested for normal distribution and equal variances for two groups. The associations were tested by comparison of two means by using independentt test for numerical data. Chisquare test or Fishers Exact test were used for categorical data. P<0.05 was taken as significant. One way ANOVA was used for multiple comparison between groups.
RESULTS
Demographic Data A total of 80 patients were recruited in the study. Among them 40 patients with DR(Group A) , and 40 patients (Group B) without DR. Females were more than male in both groups. In both groups the total of females were 52.5% and the males were 47.5% . Most of the patients were Malay, there was no statistical significant difference in race between the two groups. The age range of the patients was between 34 to 80 years. The mean age in Group A was 55.7±8.5 years and was 56.5±9.6 years in Group B (Table 1).
The Association Between Lipid Profile Among Group A and B The association of lipid profile between diabetic patients type 2 with DR (Group A) and no DR(Group B) is shown in Table 2. There is a statistical significant difference in the mean cholesterol level and LDL level between Group A and Group B (P<0.05). Triglyceride and HDL levels were found to be higher in Group A, however the difference was not significant (P>0.05). Oxidized LDL was higher in the non DR (Group B), however the mean difference was also not statistically significant.
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