Aims: To review the difference in carotid artery intima media thickness (IMT) between patients with Type 2 diabetes (DM) or impaired glucose tolerance (IGT), and control subjects.
Methods: Systematic reviews were made in order to identify cross-sectional studies using the ultrasound method. The differences between IMT in DM or IGT and control subjects were calculated. Meta-analysis using random-effects modelling was used to calculate summary measures.
Results: Twenty-three studies included 24,111 subjects; 4019 with DM and 1110 with IGT. In 20 of 21 studies, the diabetic patients had greater carotid artery IMT than the subjects in the control groups. The estimated mean difference in IMT was 0.13 (95% CI: 0.12-0.14) mm. Heterogeneity was observed and likely sources of variation were study size, diabetes duration, and ultrasound method. In three out of nine studies, the IGT patients had significant greater carotid artery IMT than the subjects in the control groups. The estimated mean difference in IMT was 0.04 (95% CI: 0.014-0.071) mm.
Conclusions: Type 2 diabetes was associated with an 0.13 mm increase in IMT compared with control subjects. In patients with IGT, the increase in IMT was about one-third of that observed in diabetes. The observed difference in IMT can be interpreted as if the diabetes patients were more than 10 years older than the control groups, and that the relative risks of myocardial infarction and stroke were increased by almost 40%, respectively.