How to Diagnose Hypoglycemia

It's very common for people with diabetes to have hypoglycemia as part of the complications of the disease. Fortunately, the diagnostic test for this condition is very simple and can be performed from the comfort of your home.
How to Diagnose Hypoglycemia

Last update: 15 July, 2021

Hypoglycemia is a condition in which the concentration of glucose in the blood falls below normal levels. This is a common complication in people with type 1 and type 2 diabetes, which occurs when there is an error in the treatment of the disease. Do you want to know how to diagnose hypoglycemia? Keep reading!

According to the American Diabetes Association (ADA), a diabetic patient has hypoglycemia when blood sugar levels are below 70 milligrams per deciliter. Diagnosis of this condition is very simple and is based on the identification of symptoms and the results of laboratory tests.

Identification of symptoms

How hypoglycemia is diagnosed: with the medical history
Identifying the symptoms of hypoglycemia is essential both inside and outside the hospital setting.

Diabetic people should have complete information about the symptoms of hypoglycemia due to its high prevalence in these patients. There are many possible causes for this condition, although it’s common for people to have low blood glucose levels after intense exercise or after long hours of fasting.

The symptoms may vary from one person to another, however, they’re very similar in most cases. Among the most frequent clinical manifestations of hypoglycemia, the following stand out:

  • Tremors
  • A sudden increase in appetite
  • Irritability
  • Confusion
  • Increase in cardiac frecuency
  • Sweating and chills

This is a very frequent condition. In fact, studies affirm that up to 90% of patients medicated with insulin have at least one episode of hypoglycemia in their life. Severe hypoglycemia can lead to accidents, coma, and even death, so early diagnosis is essential.

Medical history

It’s important to note that non-diabetic people who have repeated symptoms of hypoglycemia should consult their doctor as soon as possible. The specialist should consult their medical history and perform a thorough physical examination in order to find the possible cause.

In this sense, the doctor should inquire about their personal and family history and the symptoms they experience. The doctor will also try to link the symptoms of hypoglycemia with food intake, especially in young children.

During the physical examination, the specialist will look for signs of adjacent pathologies that may explain the symptoms presented, such as hyperthyroidism.

Lab tests

The precise way in which hypoglycemia is diagnosed is through blood tests, which will accurately show people’s blood sugar levels. In addition, they’re very useful to identify the precise cause of the condition in patients who haven’t been diagnosed with diabetes.

Capillary glucose determination

Performing a blood test while the symptoms of hypoglycemia are present will allow a timely diagnosis of the condition. It will immediately show blood glucose levels, unequivocally confirming hypoglycemia.

This test can be performed by patients from the comfort of their homes using a device called a glucometer. The procedure is fast, safe, and reliable, and offers results within minutes. To perform a reliable capillary glucose determination, the following recommendations should be followed:

  1. Wash and dry your hands to remove any food residue.
  2. Perform a small prick on the tip of a finger with an instrument called a lancet to remove a drop of blood.
  3. Place the drop of blood on a special test strip, which will be analyzed by the glucometer.
  4. Remove the strip and dispose of it properly along with the lancet.

Despite being a quick and reliable test to diagnose hypoglycemia, it should be noted that there’s a small margin of error. In fact, the Spanish Association of Pediatrics (AEP) establishes that the figure shown on the glucometer can be up to 15% lower than the figure measured in plasma.

Other analytical tests

How to diagnose hypoglycemia: with a blood sample
In addition to the typical blood glucose measurement, other tests may be necessary to help determine the origin of the disease.

Patients who suffer repeated episodes of hypoglycemia and aren’t diagnosed with diabetes mellitus should undergo other blood tests in order to determine the precise cause. Low blood sugar levels can be the result of multiple metabolic disorders that require immediate medical attention.

All the necessary values are measured with the extraction of a blood sample from a medium-caliber vessel; the blood will usually be extracted from one of the veins of the arm. Among the analytical tests that should be carried out, the following stand out:

  • Plasma quantification of ketone bodies
  • Free fatty acid concentration
  • Determination of insulin, C-peptide, cortisol, and growth hormone


The result of the blood tests is immediate when hypoglycemia is diagnosed. As previously mentioned, this condition occurs in diabetic people when they have a blood glucose concentration of fewer than 70 milligrams per deciliter.

These numbers change in people without any type of diabetes. In this sense, the blood glucose concentration must be less than 50 milligrams per deciliter in order to diagnose hypoglycemia. Laboratory tests also make it possible to determine the severity of the situation, dividing hypoglycemia as follows:

  • First level: Blood glucose values less than 70 milligrams per deciliter but greater than 54 milligrams per deciliter.
  • Second level: Blood glucose less than 54 milligrams per deciliter.
  • Third level or severe hypoglycemia: This is a state characterized by the presence of physical and psychological alterations that require immediate medical treatment.

Differential diagnostics

The frequent symptoms of hypoglycemia are very general, which is why there are various pathologies that have similar symptoms. In these cases, blood tests are essential in order to establish a differential diagnosis. Among the diseases that can manifest similar symptoms to hypoglycemia, the following stand out:

  • Heart, liver, or kidney failure
  • Side effects of some drugs
  • Malnutrition
  • Psychiatric disorders such as anxiety or depression
  • Endocrine and metabolic disorders such as hyperthyroidism
  • Hyperinsulinemia

Constant monitoring helps to diagnose hypoglycemia in time

All diabetic patients should constantly monitor blood glucose levels through the use of a glucometer. In this way, you can detect the variation in blood glucose and this will allow you and your doctor to take appropriate measures when necessary.

The doctor is the one to say when you should take your blood glucose values. However, it’s best to do it every day at the same time. Self-control and constant monitoring is essential in the treatment of chronic diseases such as diabetes, with the aim of preventing complications.

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