Insulin being a protein (which all look ~similar spectroscopically), it is not possible to measure in a no-prick format as you need physical access to it for separation/measurement (e.g. via antibody-like molecule or activity assay)

Insulin levels are massively overlooked. You can have normal blood glucose but excessive insulin levels due to insulin resistance, which leads to type 2 diabetes.

As another poster mentioned, it won't happen either invasively or non-invasively any time soon. Insulin levels aren't even part of a standard blood test in most places due to the cost.