Insulin (Fasting), Serum

Overview

The Insulin (Fasting), Serum test measures the level of insulin in the blood after fasting for 8–12 hours. Insulin is a hormone produced by the pancreas that helps regulate blood sugar (glucose) levels. This test is commonly used to evaluate insulin resistance, diabetes risk, metabolic disorders, and pancreatic function.

Why This Test is Done

Doctors may recommend this test to:

• Assess insulin resistance
• Evaluate risk for Type 2 Diabetes
• Investigate hypoglycemia (low blood sugar)
• Diagnose metabolic syndrome
• Monitor polycystic ovary syndrome (PCOS)
• Evaluate pancreatic insulin production
• Support obesity and metabolic health assessment

Symptoms That May Require Testing

• Excessive thirst or hunger
• Frequent urination
• Fatigue
• Sudden weight changes
• Darkened skin patches (Acanthosis Nigricans)
• Dizziness or sweating due to low blood sugar
• Difficulty losing weight

Test Preparation

• Fasting for 8–12 hours is usually required
• Only water is permitted during fasting
• Inform your doctor about any medications being taken

Sample Required

• Sample Type: Blood (Serum)

Normal Reference Range

Reference values may vary slightly between laboratories. Typically:

• Fasting Insulin: Approximately 2 – 25 µIU/mL

High Insulin Levels May Indicate

• Insulin resistance
• Type 2 Diabetes risk
• Obesity
• PCOS
• Metabolic syndrome
• Insulinoma (rare pancreatic tumor)

Low Insulin Levels May Indicate

• Type 1 Diabetes
• Pancreatic dysfunction
• Poor insulin production

Interpretation

This test is often interpreted along with:

• Fasting Blood Sugar (FBS)
• HbA1c
• Glucose Tolerance Test (GTT)
• HOMA-IR calculation

Benefits of Early Testing

• Helps identify diabetes risk early
• Supports lifestyle and dietary management
• Assists in monitoring metabolic health
• Enables timely medical intervestigation