Objective: Insulin resistance plays a central role in the pathogenesis and clinical course of several important human diseases such as diabetes and cardiovascular disease, particularly multi-vessel coronary artery disease (MVD). We aim to measure whole body insulin sensitivity in patients with MVD awaiting coronary artery bypass graft surgery (CABGS) and to assess any fundamental differences in their metabolic parameters when compared to a population of clinically characterised diabetic patients.
Methods: Subjects awaiting CABGS at St. Vincent’s Hospital Melbourne were recruited and grouped as diabetic or non-diabetic (n=7 per group) based on clinical history. Groups were matched according to age, sex and BMI. Prior to surgery, non-diabetic patients underwent assessment for whole body insulin sensitivity using the hyperinsulinaemic-euglycaemic clamp. Both groups underwent measurement of fasting glucose, fasting lipid profile and HbA1C.
Results: We found that non-diabetic CABGS patients were a highly insulin resistant population, with an average glucose clearance rate of 2.43 ± 0.77 mg/kg/min (Healthy glucose clearance average = 7 mg/kg/min). In addition, non-diabetic CABGS patients showed no significant differences in lipid profile and fasting glucose when compared to the diabetic group, despite not being clinically characterised as diabetic. As expected, diabetic patients were found to have a significantly higher HbA1C level (P=0.017) when compared to the non-diabetic group.
Conclusions: Patients with MVD awaiting surgery were highly insulin resistant using a gold standard test. The impact of insulin resistance in this population in terms of intra- and post-operative outcomes will be examined as part of an ongoing study.