Patient health literacy is crucial for effective patient–physician communication, and interventions targeting health literacy can use measures based on either actual performance (competence) or self-ratings (confidence). This paper analyzed the development of these measures through three studies. Study 1 reviewed articles describing the development of novel measures; Study 2 examined the citations of these studies, and Study 3 evaluated data from clinical trials registries. The literature search was conducted from April 14–27, 2023. PubMed was used as the main database in which studies on health literacy measures were searched for the systematic review (Study 1). We then used Google Scholar and the OpenCitations database to describe citation patterns of the included health literacy measures (Study 2). Finally, we evaluated confidence- or competence-based health literacy measures by extracting and analyzing trial data from ClinicalTrials.gov (Study 3). Our review included 55 health literacy measures, among which 23 (42%) were competence-based, 28 (51%) confidence-based, and 4 (7%) assessed both. Recent trends show a shift toward developing more confidence-based measures and a decline in creating new competence-based measures. Confidence-based measures were increasingly cited, whereas citations for competence-based measures have plateaued. Lastly, our findings showed a steady increase in the use of confidence-based measures in recent clinical trials and a decrease in the use of competence-based measures when controlling for sample size. This shift may be detrimental to public health given our limited knowledge about patients’ ability to meet demands of shared decision-making, especially regarding new technologies like artificial intelligence in healthcare.