Insulin resistance is associated with the metabolic syndrome and is not directly linked to coronary artery disease

Background: Insulin resistance (IR) is the key feature of the metabolic syndrome (MetS). Its association with directly visualized coronary atherosclerosis is unclear. We hypothesised that insulin resistance is associated with both angiographically determined coronary artery disease (CAD) and with the MetS.

Methods: In 986 consecutive patients undergoing coronary angiography for the evaluation CAD, IR was determined by the HOMA index; the MetS was defined according to NCEP-ATPIII criteria; and significant CAD was diagnosed when coronary stenoses ≥50% were present.

Results: HOMA IR scores were higher in MetS patients than in subjects without the MetS (4.9±6.4 vs. 2.2±2.0; p<0.001). HOMA IR did not differ significantly between patients with significant CAD and those who did not have significant CAD. When both, the presence of MetS and of significant CAD were considered, HOMA IR was significantly higher in patients with the MetS both among those who had significant CAD (4.9±6.8 vs. 2.2±1.8; p<0.001) and among those who did not have significant CAD (5.0±5.8 vs. 2.1±2.3; p<0.001), it did not differ significantly between patients with significant CAD and subjects without significant CAD among patients with the MetS nor among those without MetS. Similar results were obtained with the IDF definition of the MetS.

Conclusion: IR is significantly associated with the MetS but not with angiographically determined CAD. IR may play a greater role in the eventual precipitation of thrombosis than in the gradual progression of atherosclerosis.