Association between insulin resistance and carotid arteriosclerosis in subjects with normal fasting glucose and normal glucose tolerance.

Objective: We examined the possible association between insulin resistance and carotid arteriosclerosis in subjects who had both normal fasting glucose and normal glucose tolerance after intake of a glucose load.

Methods And Results: Our subjects were individuals who underwent general health screening at our institute, which included carotid ultrasound and oral glucose tolerance testing. Of the 1238 subjects enrolled in our study, 738 (60%) were classified as normal, defined as a normal fasting glucose level and normal glucose tolerance, and 334 (27%) and 166 (13%) were classified as borderline and diabetic, respectively, according to the criteria of the Japan Diabetes Society. The homeostasis model assessment of insulin resistance (HOMA-IR) was used as the index to measure insulin resistance. In normal-type subjects, univariate analysis showed that insulin resistance, but not insulin secretion, was associated with the presence of carotid plaque. Multivariate analysis showed that HOMA-IR was positively associated with carotid plaque in normal-type subjects, with an odds ratio of 1.19 (95% confidence interval, 1.00 to 1.41; P<0.05).

Conclusions: These data suggest the possibility that the presence of higher insulin resistance could be a risk factor for carotid arteriosclerosis in subjects with normal fasting glucose and normal glucose tolerance.