Google's "Health Guardian" feature is now available on Fitbit Air devices through Google Health app version 5.11 (Android and iOS). The feature provides monthly reports on blood pressure trends and insulin resistance estimates.
Fitbit Air users must pay $9.99 per month for Google Health Premium to access these reports. Pixel Watch 3, 4, and 5 users received Health Guardian free in September.
To receive reports, Fitbit Air users need to wear their watch for five consecutive days in a month for blood pressure tracking, or seven non-consecutive days and nights for insulin resistance tracking. Monthly reports arrive on the first of each month, starting November 1 for new Fitbit users.
Google states the insulin resistance feature is "not intended for medical purposes" and "not a pre-screener for diabetes." The blood pressure feature works by estimating readings based on heart rate, heart rate variability, and activity data, not by measuring actual blood pressure directly.
Google published research papers on both algorithms, though the blood pressure paper is not peer-reviewed. The blood pressure algorithm performed comparably to clinical measurements in testing, but the study excluded people with heart disease. The insulin resistance algorithm's real-world usefulness remains unclear.
Older Fitbit models and other devices do not support Health Guardian. Setup occurs in the Google Health app under the Metabolic section for insulin tracking and the Heart section for blood pressure tracking.