When should Insulin be retested?

When to retest insulin depends on the clinical context. Fasting insulin is commonly used to estimate insulin resistance via HOMA-IR (glucose × insulin / 22.5). In individuals with metabolic risk factors (obesity, PCOS, prediabetes) or those on insulin-sensitizing medications (metformin, GLP-1 agonists), retesting every 3–6 months can help track response. For stable patients without therapy changes, annual testing may suffice. However, a single insulin measurement has high day-to-day variability and should always be interpreted alongside fasting glucose and HbA1c. Consumer labs like MyBody-X may offer insulin testing, but evidence for routine retesting in healthy individuals is lacking. Clinical guidelines recommend insulin measurement only for specific indications (e.g., PCOS diagnosis, unexplained hypoglycemia). Caveat: No large randomized trials support routine insulin retesting in asymptomatic populations. The evidence is practice-based, not from high-quality RCTs.