PCOS and Blood Sugar/Insulin Tests

Abnormalities of blood sugar (serum glucose) and insulin are quite common in polycystic ovarian syndrome. There are several rather common blood tests to assess blood sugar status and the possibility of insulin resistance.

The tests listed below are important because up to 80% of women with PCOS may have some degree of insulin resistance.(1) Insulin resistance is thought to be one of the root causes of polycystic ovarian syndrome.

What to Do?

Your first step is to consult with your physician as to which lab tests are most appropriate for you.

If any of the tests below indicate that you have a problem with high blood sugar or insulin resistance, what can you do?

Below are the tests you should review with your doctor.

Fasting Glucose Test

A blood glucose test measures the amount of glucose (a type of sugar) in your blood. Glucose comes from carbohydrate foods. Fasting glucose measures blood sugar after you have not eaten for at least 8 hours.

A healthy fasting glucose level is between 70-90, but up to 110 is within normal limits. "Normal" is what is expected, not what is "healthy". Any "normal" test result is not necessarily an "optimal" or "healthy" test result.

A level of 111-125 indicates impaired glucose tolerance or insulin resistance. A fasting level over 125 indicates type 2 diabetes.

Fasting Insulin Test

Insulin is a hormone that helps your body use and control the amount of glucose in your blood. Insulin is produced in the pancreas gland and released into the blood when the amount of glucose in the blood rises.

Normally, your blood glucose levels increase slightly after you eat carbohydrate foods. This increase causes your pancreas to release insulin so that your blood glucose levels do not get too high. However, some women with PCOS tend to have chronically high levels of insulin that do not drop back to normal levels. This is a condition called hyperinsulinism and has negative health consequences.

Fasting insulin measures insulin between meals, when it should be at its lowest.

A fasting insulin of 10-13 generally indicates some insulin resistance, and levels above 13 indicate greater insulin resistance.

Glucose/Insulin Ratio

The ratio of fasting glucose to fasting insulin may also provide insights. A glucose to insulin ration of less than 4.5 is suggestive of insulin resistance.

Glycohemoglobin A1C (HbA1C)

In contrast to fasting glucose, glycohemoglobin A1C (HbA1C) is a longer-term measure of your blood sugar levels. This test measures average glucose levels over the past 3 months. You can think of fasting glucose as a snapshot at a point in time whereas HbA1C is like a motion picture over a period of time.

Your HbA1C should be under 6% to show good blood sugar control. A chronically elevated HbA1C not only puts your health at risk, but it also is associated with increased infertility and indicates a relatively unfavorable environment for a successful pregnancy.

By the way, "glycohemoglobin" is glucose that has combined with a blood cell protein. Glycohemoglobin is one example of an unhealthy process. The combining of glucose with proteins results in toxic substances called glycosylation end-products, or "AGEs". Elevated levels of AGEs indicate that a degenerative process is underway.

The AGE reaction is not reversible, and AGEs accumulate over the lifetime of a protein. Your goal is to prevent AGEs from forming in the first place, by modifying diet, lifestyle, and other factors to promote healthy blood sugar control.

Glucose Tolerance Test (GTT)

The oral glucose tolerance test (OGTT or GTT ) assesses your ability to handle a load of sugar (glucose). An abnormal test result in PCOS women may suggest the presence of diabetes or a pre-diabetic condition. Abnormal findings may also indicate other problems such as reactive hypoglycemia.

The GTT may also be used to check pregnant women for gestational diabetes. When done for this purpose, the test is called a glucose challenge screening test, and it is usually done during the 24th to the 28th week of pregnancy. You may have an increased chance of developing gestational diabetes if you:

  • Have PCOS (polycystic ovary syndrome)
  • Have had gestational diabetes during a previous pregnancy.
  • Have previously given birth to a baby who weighed more than 8.8 lb(4 kg).
  • Are younger than age 25 and were overweight before getting pregnant.

The GTT consists of drinking a small amount of glucose solution and measuring the blood glucose values every hour to get a curve. The form of the curve tells a lot about the body's sugar metabolism. The test may last several hours.

The glucose tolerance test is not very commonly used since it is time-consuming and inconvenient.

(1) Carmina E et al, Use of fasting blood to assess the prevalence of insulin resistance in women with polycystic ovary syndrome, Fertil Steril. 2004 Sep;82(3):661-5

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