Díaz Lab Testing Store › Fasting Insulin | Serum (Quest) Image 1 of 1 Fasting Insulin | Serum (Quest) $27.00 Detects insulin resistance before blood sugar becomes abnormal — the earliest warning sign of metabolic dysfunction. Add To Cart Added! Detects insulin resistance before blood sugar becomes abnormal — the earliest warning sign of metabolic dysfunction. Add-on | Interpretation for Individual Markers $17.00 Add Added!