Insulin sensitivity as a risk factor for common carotid intima media thickness (IMT): its relation to atherosclerosis

INTRODUCTION: The relationship between insulin resistance and atherosclerosis (ATH) in non-diabetic hypertensive patients from the Asian Indian population remains poorly understood. To resolve this issue, the present study was designed to analyze whether insulin sensitivity in a non-diabetic individual is related to the development of ATH.(by using IMT as an index) and whether this relationship is dependent on the presence of other cardiovascular disease (CVD) risk factors such as dyslipidemia and hypertension. METHODOLOGY: This study included 68 healthy controls with no diabetes and hypertension and 41 hypertensive patients who underwent four-point oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT). A biochemical profile, beta mode ultrasonography for intima media thickness of carotid artery, and ECG determination was carried out. RESULTS: Hypertensive patients in our study exhibited significantly increased abdominal obesity. Blood pressure, fasting and 2 hr plasma glucose (4.62 +/- 0.08 and 5.55 +/- 0.17 mmol/l), and triglyceride (1.47 +/- 0.067 mmol/l) levels were compared to those of control subjects (p < 0.05). The fasting insulin levels and HOMA-IR were also significantly increased and Composite Insulin Sensitivity Index (CISI) reduced compared to controls with p < 0.01. Intima media thickness of the left (0.08 +/- 0.01) and right (0.069 +/- 0.008) CA were both significantly increased in hypertensives (p < 0.01). Correlation analysis showed that IMT of the left carotid artery was significantly associated with triglyceride levels (r = 0.813, p < 0.05) but not with insulin measures such as HOMA-IR and CISI. CONCLUSION: Hyperinsulinemia was observed in our non-diabetic hypertensive patients, but no association was found between IMT and insulin resistance. That IMT of hypertensives was associated with triglyceride levels suggests that high levels of insulin may be related to the development of ATH indirectly through its effects on lipid metabolism in our population.