<i>The history of blood glucose testing is informative here.</i><p>You&#x27;re conflating a <i>diagnostic</i> test with a test that patients need to control <i>dosing</i> (of insulin).  To make a diagnosis of diabetes, such frequent testing is not any more informative.  Better tests, such as HbA1C, have been developed to indirectly measure blood glucose levels over a 3-month timescale, which is more appropriate for diagnosis.<p>I don&#x27;t think there&#x27;s any evidence yet that people being able to monitor their lipid levels while eating provides any useful medical information, unless you have some kind of (incredibly rare) inherited lipid metabolism deficiency.<p><i>comparing blood tests between a bipolar person&#x27;s manic and depressive phases would be fascinating, but no one does it.</i><p>There in fact has been plenty of work on this, but in a research setting, where it belongs. See section 6 of <a href="http:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;27017833" rel="nofollow">http:&#x2F;&#x2F;www.ncbi.nlm.nih.gov&#x2F;pubmed&#x2F;27017833</a><p><i>it&#x27;s the twenty-first century and the rate of iodine deficiency is 9%.</i><p>Micronutrient deficiencies are usually a result of dietary choices. This problem is more easily solved by encouraging everyone to take a daily multivitamin, which would be completely prophylactic, than by encouraging the same population to subscribe to series of blood tests that may or may not reveal the problem, and would require follow-up action. Again, think about it from a population health perspective.