Increased carotid intima–media thickness (CIMT) levels in patients with type 1 diabetes mellitus (T1DM): A meta-analysis

Abstract

Aim

To derive a more precise estimation of carotid intima–media thickness (CIMT) levels in patients with type 1 diabetes mellitus (T1DM) by meta-analysis.

Methods

PubMed and Embase databases were searched to identify all available studies comparing CIMT levels between T1DM group and control group. Meta-analysis was performed to compare the difference of overall mean CIMT levels between the two groups. Publication bias was evaluated by funnel plot, Begg' test and Egger' test. Meta-regression analysis was conducted to investigate the influential factors on CIMT difference. The meta-analysis was conducted by STATA 12.0 software.

Results

A total of 1840 articles were obtained after searching databases; 47 studies were finally included in the meta-analysis. Significant heterogeneity was observed among these studies (Q = 768.75, P < 0.001, I² = 94.0%). Compared with the control group, the T1DM group had significantly higher CIMT levels (standardized mean difference: 1.01, 95% CI: 0.75–1.28; P < 0.001). A likely source of heterogeneity was Newcastle–Ottawa Scale (NOS) scores and sample size ratio of patents and controls. The funnel plot did not show a skewed or asymmetrical shape, and the result of Begg' test and Egger' test was P = 0.178 and P = 0.145 respectively. Accordingly, it could be assumed that publication bias was not present.

Conclusion

T1DM patients have significantly increased CIMT levels compared to control subjects.

Introduction

Type 1 diabetes mellitus (T1DM) is also called insulin-dependent diabetes mellitus (IDDM), which is dependent on insulin therapy from beginning of T1DM and have to be used in the reminder of patients' life. Some epidemiological studies have demonstrated a rising incidence of T1DM worldwide in the past few decades. In European, children under 14 years, the incidence of T1DM increased on average by 3.2% per year (Schwab et al., 2007). Diabetes has long been recognized as an independent risk factor for coronary artery disease (CAD). T1DM is associated with an increased cardiovascular (CV) morbidity and mortality as compared with the general population (Distiller, Joffe, Brown, & Distiller, 2010). The morbidity and mortality due to coronary artery disease are two to four times greater than in healthy control subjects (Muis et al., 2005, Raggi et al., 2005). And cardiovascular disease is based on atherosclerosis (AS), the hallmark of cardiovascular diseases, which is the leading cause of mortality all over the world. Many studies reported that patients with diabetes have 2 to 10 times increased risk of developing atherosclerotic disease (Atabek et al., 2014, Lee et al., 2011, Pozza et al., 2010, Tantawy et al., 2009). Carotid intima–media thickness (CIMT) level is the symbol of early atherosclerosis, it has been shown to be the marker of preclinical atherosclerosis (Gimenez et al., 2010), and measurement of the CIMT is independently associated with an increased cardiovascular disease (Atabek, Pirgon, Kurtoglu, & Imamoglu, 2006). Noninvasive surrogate markers of early atherosclerosis should be used to allow the early detection of atherosclerosis before leading to disease. High-resolution ultrasonographic measurement of the CIMT is one such method (Larsen et al., 2005, Tyrrell et al., 2010).

In recent years, a great many studies have been performed to compare the mean CIMT difference between patients with T1DM and healthy controls. However, these studies have shown inconsistent or even contradictory findings. The inconsistency is likely due to different publication years, nations, composition of age and sex, disease duration of patients, publication bias, etc. This meta-analysis was undertaken to derive a more precise estimation of the difference in CIMT between T1DM patients and control subjects.