Insulin resistance and atherosclerosis in diabetes mellitus

The aim of this study was to test our hypothesis that insulin resistance determines systemic atherosclerosis in type 2 diabetic patients. The design of the study was cross-sectional and included 28 type 2 patients with 48 type 1 patients as controls. The total daily insulin dose required to maintain glycosylated hemoglobin, HbA(1c), at 6.0% for 1 year was used as a measure of long-term insulin resistance. Systemic atherosclerosis was estimated by the toe systolic blood pressure index (TSPI). The results showed that total daily insulin dose was closely and independently associated with TSPI (r =.4652, partial P =.0064) in type 2 diabetic patients with secondary failure, even when adjusted for serum C-peptide (r =.4443, partial P =.00123). The association was absent in type 1 patients. Established risk factors were not associated with TSPI, but the products between individual risk factors and insulin dose were closely associated with TSPI. In conclusion, the daily insulin dose is associated with peripheral atherosclerosis in type 2 diabetic patients with high insulin resistance, but not in type 1 diabetes. The effect is additive to a lesser, underlying effect of established risk factors on atherosclerosis. Longstanding insulin resistance, as estimated by the daily insulin dose, is a determinant of atherogenesis.