Does Fasting For Long Before A Blood Test Show Inaccurate Insulin Levels?

Posted on Sat, 27 Dec 2014

Question: I had a blood test to check my insulin levels to see how bad my insulin resistance is. I fasted for about 14 hours before the test. Will this make the result inaccurate. The result was a very low reading compared to my last blood test. It was 25, it said it was now 12. Should I redo the blood test. How inaccurate was the one I just did?

Answered by Dr. Shehzad Topiwala (15 minutes later)

Brief Answer:
Insulin test

Detailed Answer:
Insulin blood tests are not deemed worthwhile in real world practice for the purpose of assessing insulin resistance. They were in vogue for sometime in recent past but lately have been relegated back to research domains.

There are many reasons for this.

1 Test method is challenging.
Not all labs can perform the test accurately. It requires a sophisticated lab to run the test with scientifically correct technique

2 Interpretation can be non specific

Insulin levels alone are not reliable as objective markers of Insulin resistance. Hence, it is not worth tracking and trending insulin levels over time.

I understand you are thinking logically and trying to ascertain a pattern but unfortunately this test has not lived up to it's promise to provide such information

3 HOMA IR
is a complex scientific tool that utilizes Insulin blood test results in an equation to estimate degree of insulin resistance.
Again, this too is largely restricted to clinical research and not day-to-day medical practice

For the above reasons, I am unable to give you a precise answer to your direct query regarding valid comparison of your insulin levels.

However, Insulin levels are routinely used for diagnosing the cause of low blood glucose levels in those without diabetes. Here they are of immense value.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Shehzad Topiwala (48 minutes later)

So what should i do to get an acurate diagnosis for insulin resistance? I have also been diagnosed with PCOS from about 6 years ago, and had gestational diabetes (which went away straight after giving birth)

Answered by Dr. Shehzad Topiwala (17 hours later)

Brief Answer:
Follow up

Detailed Answer:
Insulin resistance is not a diagnostic term for a medical disease. It refers to a mechanism which has been shown to be one of the causes of pre diabetes/diabetes. It is also commonly associated with PCOS.

It is often a clinical diagnosis meaning there are signs on examination such as 'acanthosis nigricans' and sin tags that suggest the likelihood of this problem, along with overweight/obesity and central fat accumulation in the midriff/belly area.

Furthermore, presence of pre diabetes/ type 2 diabetes indicates its indirect existence.

Note: For more information on hormonal imbalance symptoms or unmanaged diabetes with other comorbid conditions, get back to us & Consult with an Endocrinologist. Click here to book an appointment.

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar