A new non-invasive biomarker sensor from Rockley Photonics seem to address this by using infrared instead of traditional LEDs for measuring biomarkers. Since it's infrared and that the melanin pigment is invisible to it; Color of the skin is not a factor for such sensor.
Upcoming wearables like smartwatches with such laser-based spectrophotometer sensors are en-route and can measure wide range of biomarkers from blood glucose to blood pressure.