Insulin hypersecretion, not resistance, tied to arterial stiffness in young adults

Postloading insulinaemia appears to be linked to arterial stiffness in young individuals, a recent Japan study has found. In contrast, insulin sensitivity (SI) shows no such effect.

The study included 1,193 young Japanese persons (<40 years of age, 934 men) who underwent a 75-g oral glucose tolerance test (OGTT) for the measurement of relevant parameters including plasma glucose, insulin, and proinsulin. Arterial stiffness was assessed as pulse wave velocity (PWV).

Several multivariate regression models were constructed to identify factors contributing to arterial stiffness. Levels of immunoreactive insulin (IRI) and proinsulin, as well as their corresponding areas under the curve (AUCs), were found to be positively associated with higher PWV.

However, after complete adjustments for covariates, the AUC of IRI remained the only OGTT variable significantly associated with PWV (t, 2.54; p<0.05). Other correlates included male sex, body mass index, heart rate, and mean blood pressure (p<0.01 for all). Notably, indices of insulin sensitivity, including the Matsuda index, were not significantly associated with PWV.

According to the researchers, the findings suggested that “postloading insulinemia was independently associated with arterial stiffness in young Japanese persons. Insulin hypersecretion, rather than insulin resistance, seemed to be related to arterial stiffness in this population.”

Important study limitations included its cross-sectional design, which precluded causal analysis; the specific characteristics of the study sample, which may limit the generalizability of the findings; and the lack of exact and complete data regarding the participants’ lifestyle behaviours such as smoking and exercise.