Systematic review and meta-analysis assessing the status of carotid intima-media thickness and lipid profiles in type 2 diabetes mellitus

Objectives Carotid intima-media thickness (CIMT) is a measurement for subclinical atherosclerosis and has been associated with overall cardiovascular diseases, especially in type 2 diabetes mellitus (T2DM). We aimed to assess the status of carotid health and lipid profile in T2DM. Design This systematic review and meta-analysis synthesised data published from clinical studies. Data sources Google Scholar, PubMed and Scopus were searched from inception to 18 January 2024. Eligibility criteria for selecting studies Studies conducted in patients with T2DM and those without T2DM were included. Studies conducted in T2DM adults evaluating carotid status and lipid profile were considered. Data extraction and synthesis Two authors independently used standardised methods to comprehensively search, screen and extract data from all relevant studies. The risk of bias was assessed using the Newcastle-Ottawa checklist. Meta-analysis was conducted using Review Manager and metaHun through random effects models. The random effect model was used due to high heterogeneity. Results Evidence was analysed from 57 studies with a sample size of 29 502 (8254 T2DM and 21 248 people without T2DM). There was a significantly higher CIMT, with a standardised mean difference (SMD) of 1.01 (95% CI 0.75, 1.26, p<0.00001). Additionally, there was an elevated triglyceride (TG) (SMD=1.12, 95% CI 0.82, 1.41, p<0.00001), total cholesterol (TC), (SMD=0.24, 95% CI 0.02, 0.46, p=0.03) and low-density lipoprotein-cholesterol (LDL-C), (SMD=0.35, 95% CI 0.11, 0.59, p=0.004) in patients with T2DM compared with those without T2DM. Furthermore, a significant decrease in high-density lipoprotein cholesterol (HDL-C) was observed in the T2DM compared with people without T2DM, SMD=-0.79, 95% CI -0.96, -0.62, p<0.00001). Age, body mass index and hypertension were associated with increased CIMT and TG and decreased HDL-C in T2DM. Additionally, age, gender and hypertension were associated with an increased LDL-C in T2DM. Conclusion Our findings suggest that an increased CIMT is accompanied by increased TG, TC, LDL-C and HDL-C reduction in patients with T2DM.