What lab test is considered best to diagnose insulin resistance?

The "ultimate": is a GLUCOSE TOLERANCE TEST with INSULIN Measurements. This is a test run by ENDOCRINOLOGY laboratories and your PCP can arrange for such a consultation! Hope this is helpful! Dr Z

Wrong question: There is no single best test. Usually this is a clinical determination made on evaluation of the whole presentation and a look at A1C. The advise is first to adopt a healthy diet, exercise regularly, and lose weight. Metformin might be considered. Extensive glucose tolerance tests and blood insulin levels are generally not practical.