Understanding Your Fasting Insulin Test Results

Diabetes has become a global health challenge. About 10.5% (536.6 million) of adults aged 20-79 have diabetes mellitus, and the overall number is projected to rise to 12.2% by 2045, equivalent to 783.2 million. One major promoting factor of type 2 diabetes mellitus is insulin resistance, which can be measured using a fasting insulin test. As the name suggests, this test is performed after you have fasted for at least 8 hours. 

The fasting insulin test is carried out with other tests to confirm the diagnosis of insulin resistance, prediabetes, and type 2 diabetes. Now, let us examine in detail what your reports mean by the results of the fasting insulin level.

What is Insulin and How Does it Work?

Insulin is an endocrine hormone produced by the pancreas that helps your body use glucose (sugar) for energy. When you eat food containing carbohydrates, your body converts them into glucose and sends it into your bloodstream. To deal with this rise in blood sugar, the pancreas releases insulin into your blood.

Insulin works as the key that unlocks your cells and allows glucose to enter so that you can have energy. It also signals your liver and muscle cells to store any excess glucose as glycogen for later use. When your cells are sensitive to the hormone insulin, this process works well, and blood sugar levels remain stable. However, if any issues occur in the pancreas’s ability to produce adequate insulin, the blood sugar levels fluctuate and can result in different metabolic disorders like diabetes. 

What Happens During a Fasting Insulin Test?

These are the following steps you can expect during a fasting serum insulin test: 

  • For the fasting insulin test, a professional will draw a blood sample, usually from a vein in your arm. 
  • You will be advised to fast for at least 8 hours before the test. 
  • You will also be advised to avoid taking certain medications or supplements, such as biotin, before the test. Your doctor will provide specific instructions.
  • The blood sample is then analysed in a laboratory to determine the insulin level in your blood.
  • The test is generally quick and carries minimal risks, such as slight pain or bruising at the injection site.

Interpreting Fasting Insulin Test Results

The fasting insulin normal range is 2-20 μU/mL. However, the optimal level is below 8 μU/mL. Here is a table showing the interpretations of different fasting insulin levels:

Fasting Insulin Level (μU/mL) Interpretation
< 2 Abnormally low insulin
2-5 Optimal
5-20 Normal
20-30 Early insulin resistance
> 30 Significant insulin resistance, high risk of type 2 diabetes

A high fasting insulin level, known as hyperinsulinemia, indicates that your body is producing too much insulin to maintain normal blood glucose levels. This often means your cells are becoming resistant to insulin's effects (insulin resistance).

When you have insulin resistance, your body's cells don't respond effectively to insulin, so glucose builds up in your blood. Your pancreas then compensates by producing more insulin. Over time, this can lead to consistently high blood sugar levels and can result in type 2 diabetes.

Conditions Related to Abnormal Fasting Insulin Levels

Abnormal fasting insulin level can be indicative of a variety of health disorders:

  1. Insulin Resistance and Prediabetes: High fasting insulin levels are the first-middle sign that heralds developing insulin resistance. Uncontrolled insulin resistance could result in prediabetes and type 2 diabetes. 
  2. Metabolic Syndrome: This is a term for a group of concurrent disorders that increase your risk of developing heart disease, stroke, and type 2 diabetes. Elevated levels of fasting insulin indicate metabolic syndrome.
  3. Polycystic Ovary Syndrome (PCOS): Resistance to insulin and high insulin levels usually accompany PCOS in women, raising the overall level of androgen and causing a malfunction in periods.
  4. Insulinoma: This is also the rare kind of pancreatic tumor by which a pancreas can be 'fooled' into producing too much insulin, leading to low blood sugar levels, also known as hypoglycemia.
  5. Cushing's Syndrome: This is a condition in which the body is exposed to too high levels of the hormone cortisol, which might elevate the insulin levels and cause insulin resistance.

Therefore, patients are advised to monitor their glucose levels during fasting and after meals. This helps detect these conditions early and guide treatment decisions. If your serum insulin test results turn out abnormal, your doctor may order other tests or recommend lifestyle changes to improve your insulin sensitivity and health.

Lifestyle Changes to Improve Insulin Sensitivity

If your fasting insulin test reveals elevated levels, making lifestyle changes can help improve your insulin sensitivity and reduce your risk of type 2 diabetes and other related health issues. You can follow these effective strategies:

  1. Maintain A Healthy Weight:  Losing excess body fat—more importantly, excess fat around your waist—can greatly increase your insulin sensitivity.
  2. Exercise Regularly: Physical activity helps your cells use insulin more effectively. Doctors suggest 150 minutes of moderate-intensity exercise per week.
  3. Eat a Balanced Diet: Focus on whole, unprocessed foods that are high in fiber, with healthy fats and lean proteins. Limit refined carbohydrates and sugars.
  4. Manage Stress: Long-term stress makes insulin resistance worse. Engage in some stress-reducing activities like meditation, deep breathing, or yoga.
  5. Get Enough Sleep: Poor sleep habits and duration may reduce your insulin sensitivity. You should aim to get 7-9 hours of good quality sleep each night.
  6. Consider Medication: Under certain circumstances, your doctor may prescribe medications such as metformin, which help boost a person's sensitivity to insulin.

Proactive Steps for Better Insulin Health

If you have symptoms of insulin resistance, such as increased thirst, frequent urination, or blurred vision, or if you have a family history of diabetes, it's important to discuss the fasting insulin test with your doctor. They can help you interpret your results and develop a plan to improve your insulin sensitivity and overall health.

Additionally, if you have been diagnosed with prediabetes or type 2 diabetes, your doctor may use the fasting insulin test to monitor your condition and adjust your treatment plan as needed.

Maintain a healthy daily routine and self-monitoring to control your health. With the Aware App, you can track your blood glucose levels, log your progress, and get meaningful insights to help you live life to the fullest while managing your health.

FAQ's

  1. What happens if fasting insulin is high? 

High fasting insulin levels indicate insulin resistance, meaning your body needs more insulin than normal to keep blood sugar levels stable. If this persists unchecked, it leads first to a condition called prediabetes, followed by the onset of type 2 diabetes and eventually other serious health complications, especially heart diseases. Thus, it may require necessary lifestyle changes and medication to improve insulin sensitivity.

  1. What is a normal fasting insulin level in μU/mL? 

The fasting insulin normal range is 2-20 μU/mL; however, for optimal health, it should be below 5 μU/mL. Between 5-20 μU/mL, the results will be within normal limits, while anything above 20 μU/mL will mean that the person has developed insulin resistance. 

  1. How to reduce fasting insulin? 

Make lifestyle changes, including weight loss if you are overweight or obese, to reduce fasting insulin levels and improve insulin sensitivity. Get regular exercise, eat a balanced diet low in refined carbohydrates and high in fiber, manage stress, and get enough sleep. Some people will also require medicines.


About the Author

Dr. Satish Madiraju, a renowned cardiologist is passionate about consumer heart health and is on a mission to prevent a million heart attacks. He shares his expertise not only on heart health but also on leadership, digital health, and improving patient experience.
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