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The insulin curve is a test that is usually done together with the sugar curve to look at how the body secretes insulin and metabolizes glucose. It is performed when diabetes or similar diseases are suspected, in which there is a disturbance of carbohydrate metabolism. Learn how to prepare for an insulin curve test, what the test is about, and how to interpret its results.
Why is the insulin curve tested?
The sugar and insulin curve in the diagnosis of diabetes mellitus serve as the basic test. Insulin is a hormone that plays a key role in the metabolism of sugar by the cells: its presence in the blood signals the absorption of glucose. If insulin secretion or the way cells respond to it is not appropriate, it can lead to a variety of diabetic disorders.
The following symptoms are indications for the study of the insulin curve, which are considered to be early signs of the onset of diabetes:
- recurrent itching, urinary tract infections and increased urination
- detection of glucose in urine,
- postprandial hypoglycemia, i.e. symptoms of a drop in sugar levels after eating a meal, especially high in carbohydrates,
- family history of diabetes
- hypertension, overweight, obesity.
The glycemic and insulin curves are also routinely performed in pregnant women due to the possibility of gestational diabetes.
How to prepare for the study of the insulin curve?
The most important element that must be taken care of in order to be fully reliable is the arrival on an empty stomach. The sugar and insulin curve is usually performed in the morning, so that the patient is after a minimum ten-hour all-night fast.
It happens that a sudden jump in glucose after such fasting leads to fainting, which makes the test impossible and should be repeated at a different time.
To minimize the risk of a jump, it is best to stay seated after giving glucose and avoid any exertion. It is also important because any effort increases the demand for glucose and thus distorts the test results.
In order not to distort the results, apart from fasting, it is worth noting that you do not drink alcohol or smoke for three days before the test. It is best to limit yourself to drinking water. There are no specific dietary indications except that carbohydrate intake should not be restricted. It may turn out that some medications you take may affect the test result, so your doctor may recommend discontinuing them 7-14 days before the test. This is especially true of metformin.
The insulin and glycemic curve can only be performed by healthy people, because any infections may also affect the test result. The solution with glucose must not be dripped with lemon juice. If you vomit fluid, the test will need to be repeated after consulting your doctor about this information.
The insulin curve – what does the test look like?
The insulin curve is a graph that shows how your body releases insulin when it is in contact with glucose. Most often it is a dose of 75 g of pure glucose dissolved in 200-300 ml of warm water, which should be drunk as soon as possible. The most popular is the three-point insulin curve: Insulin levels are tested first before glucose administration, then one hour after administration, and finally two hours after administration.
If your doctor has chosen to create an insulin and sugar curve, each curve requires separate blood samples. This means that blood is drawn twice at each point for a total of six times.
There may be times when your doctor decides to increase the number of samples for greater measurement accuracy.
What are the results of the insulin curve and how to interpret them?
Both the glycemic curve and the insulin curve give the results defining the concentration of glucose and insulin in the blood, respectively, at the subsequent measurement points. The norms for the three-point insulin curve are as follows:
- 10 μIU / ml fasting,
- up to 50 μIU / ml after an hour,
- up to 30 μIU / ml after two hours.
Ultimately, insulin levels should return to baseline after two hours. Measurements of glucose and insulin are usually performed together to calculate the so-called HOMA-IR coefficient, determining the ratio of sugar level to insulin level. It gives preliminary information on whether the patient suffers from insulin resistance, i.e. the body’s too weak response to insulin.
The sugar and insulin results should also be interpreted separately as they provide the physician with a lot of other information. It is therefore important that you leave the final interpretation of the results to your doctor. Posting your research results on internet forums for interpretation by anonymous users is not the way to proper treatment.
The insulin curve in pregnancy – why is it worth doing the tests?
The insulin curve is also done in pregnancy. Like the sugar curve, the test is to check that a woman does not have gestational diabetes. The main indications for the test are, inter alia, age over 35, gestational diabetes in previous pregnancies, hypertension and obesity.
Check how gestational diabetes can manifest itself
The norm of the fasting insulin curve in pregnant women should be 3,8-5,5 mmol / l, after the first dose of glucose – less than 10 mmol / l, and two hours after glucose administration – about 7,8 mmol / l. It is worth remembering that after drinking glucose, you may experience a gag reflex. It is not worth making sudden movements. It is best to remain resting for two hours.
Insulin curve – test price
The price of testing the insulin curve is not high. Usually it ranges around 30 zlotys. It is often done bundled with the sugar curve. Then the price is higher. Three glucose measurements and three insulin measurements can cost about PLN 120.
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