Final answer:
Historically, the thermometer was the primary self-testing equipment in American households for measuring body temperature, but other tools like glucometers and sphygmomanometers have since become widely used for monitoring other health conditions.
Step-by-step explanation:
At one time, the thermometer was the only self-testing equipment found in most Americans' homes. Despite advancements in medical technology and the development of various self-testing devices for medical conditions, the thermometer remains a fundamental tool due to its simplicity and the universal need to measure body temperature as a primary indicator of health. Over the years, diagnostic tools for conditions such as diabetes have evolved, as seen in the transition from complex lab-based glucose testing to the use of test strips and modern glucometers that need only a drop of blood and take less than a minute to use. Moreover, sphygmomanometers, used for monitoring blood pressure, have become more accessible for home use in various forms such as arm cuffs and wrist monitors, which are common in households today along with digital versions.