Serum alkaline phosphatase (ALP) is known to be associated with cardiovascular events and cerebral arteriosclerosis. However, the link between ALP and early arteriosclerosis remains unclear. This study investigated the relationship between ALP and early arteriosclerosis assessed by brachial–ankle pulse wave velocity (Ba-PWV).

This retrospective analysis included 5011 participants who underwent health examinations, including ALP and Ba-PWV measurement, at the Second Hospital of Hebei Medical University from 2012 to 2017. Regression analysis, smoothing function analysis in the generalized additive model (GAM), threshold effect analysis, and subgroup analyses were performed.

Multivariate regression analysis identified a significantly positive association between serum ALP and arteriosclerosis [odds ratio (OR) = 1.008, 95% confidence interval (CI) 1.004–1.011, P < 0.001]. Smoothing function analysis indicated a two-stage association between ALP and arteriosclerosis. Furthermore, threshold effect analysis determined an inflection point at 135 U/l, below which the relationship was linearly positive and above which the risk of arteriosclerosis did not increase prominently with increasing ALP (OR = 1.009, 95% CI: 1.005–1.013, P < 0.001; OR = 0.976, 95% CI: 0.952–1.002, P = 0.068). However, ALP was not associated with arteriosclerosis only in participants with diabetes (OR = 0.996, 95% CI: 0.979–1.014, P = 0.690). A positive association between Ba-PWV and arteriosclerosis was observed for both the arteriosclerosis and nonarteriosclerosis groups (β = 9.10, 95% CI: 4.67–13.54, P < 0.001; β = 8.02, 95% CI: 5.67–10.37, P < 0.001).

In this study, the serum ALP level was positively associated with early arteriosclerosis, with a saturation effect beyond ALP = 135 U/l. However, the positive association between ALP and arteriosclerosis was unclear in adults with diabetes.