What are the tests to determine the type of diabetes?
To determine the type of diabetes (1st or 2nd type), highly specialized stimulation tests are performed, in which substances stimulating the secretion of insulin are introduced into the blood; based on the results, it is assessed whether there is an absolute lack of insulin or a relative deficiency:
autoantibody test – this is a highly specialized test that looks for abnormal autoantibodies in the blood, directed against the beta cells of the pancreas; the presence of such antibodies strongly suggests type 1 diabetes, but their absence does not necessarily mean type 2 diabetes.
glycated hemoglobin (HbA1C) test – this is also a highly specialized test that provides retrospective information on blood sugar values in the last 3 months; high glucose figuratively speaking “sticks” to the hemoglobin of red blood cells, which live on average 3 months. This study provides important information regarding blood sugar control when providing treatment. Normal HbA1C values are below 6.1%, and the goal for diabetics is below 6.5%. A high HbA1C value means high values and poor blood sugar control in the last 3 months. HbA1C values are also associated with the risk of developing diabetic microangiopathy (damage to the smallest blood vessels), each 1% reduction in HbA1c reduces this risk by 10%.
examination of cholesterol, triglycerides, “good” (HDL) and “bad” (LDL) cholesterol to assess the presence of additional disorders in the exchange and the presence of the so-called “metabolic syndrome X”
examination of glucose in the urine – normally there is no glucose in the urine; a positive urine glucose test usually means a high blood sugar value; each person’s kidneys have a “threshold”-the value of blood sugar above which they pass glucose into the urine; usually this threshold is between 9 and 11 mmol/l; this threshold is lowered to a certain extent during pregnancy.
examination of microalbumin in the urine – this is a specific test for establishing early kidney damage (it occurs as a result of the defeat of the small blood vessels of the renal cortex)
vibration sensitivity test – this is a test of the function of the peripheral nerves of the limbs, they are often damaged in diabetes mellitus
fundus examination – performed after dilating the pupils with a device called an “ophthalmoscope”, assessing the presence of diabetic retinopathy, its type, etc.
What is the glucose tolerance test?
Glucose tolerance test (also called glucose load) – this is a test for establishing the diagnosis in controversial, borderline, and unclear blood sugar values determined by other studies. This test is the most accurate, it is the “gold standard” for diagnosing type 2 diabetes when symptoms appear gradually and often the disease is discovered accidentally. The test is carried out as follows: after 12 hours of fasting, the patient slowly swallows 75 grams of glucose dissolved in 300 grams of water, before drinking the sweet liquid, blood is taken, and fasting blood sugar is tested; it is important that the patient did not fast in the days before the “12 hours of fasting”, during these days the usual intake of carbohydrates should be observed; on the 2nd hour of glucose ingestion, venous blood is taken again and the blood sugar level is examined; it is important that during these 2 hours the patients do not move intensively, do not take food and drinks and do not smoke.
Based on the results of the glucose load, the following conditions are distinguished:
- fasting blood sugar below 6.1 mmol/l and 2nd-hour blood sugar below 7.8 mmol/l means normal glucose tolerance or normal blood sugar control; such a result excludes any presence of diabetes or a prediabetic condition
- fasting blood sugar above 6.1 and below 7 mmol/l and blood sugar at the 2nd hour above 7.8 and below 11.1 mmol/l means impaired (reduced) glucose tolerance, i.e. poor blood sugar control exists, but diabetes mellitus is not present; people with impaired glucose tolerance are at high risk of developing diabetes, therefore a special diet and physical activity regime is usually applied to them (every year 5-6% of this group of people develop diabetes); recently, it is believed that impaired glucose tolerance in itself carries a higher risk of developing cardiovascular diseases and complications and therefore should be treated more actively.
- fasting blood sugar above 7 mmol/l and blood sugar at the 2nd hour above 11.1 mmol/l definitely means diabetes mellitus
How is blood sugar determined?
There are several methods, each of which has a certain diagnostic value:
- rapid method using factory strips – this is a quick, screening test (for mass, screening, and prophylactic application) that can be applied in home or outpatient settings. After pricking the tip of one of the fingers, a drop of blood is dripped onto a special strip and the latter is inserted into a device called a glucometer. After seconds, the blood sugar value in mmol/l appears on the device’s display. This method is relatively imprecise (up to 10% error) and is therefore not used for definitive diagnosis. His role is to screen out those people who need a more precise examination. Glucose pricks and blood glucose measurements with a strip and meter are often used to monitor blood glucose values by diabetics themselves at home.
- fasting blood sugar – this method is carried out after taking venous blood in a laboratory; “fasting” means that the patient has not taken any food or liquid for 8 hours before the examination. According to the World Health Organization (WHO), twice (in two different tests, usually on different days) fasting blood sugar above 7 mmol/l means the presence of diabetes mellitus. Since the blood sugar values are affected by many factors, the test is repeated on two different days. For each of the tests, the patient must not have consumed food or drink in the last 8 hours (it is done in the morning), not be sick (including “cold”, with a high temperature, etc.), and not have taken drugs that can affect glucose levels.
- accidental measurement of blood sugar – after taking blood in a laboratory, blood sugar is tested without the patient fasting; establishing a value of glucose in the blood above 11.1 mmol/l means diabetes mellitus.
How is the diabetes diagnosis made?
If the doctor examines you for the first time, he will question you carefully about the exact characteristics of your complaints, their duration, and manner of expression, the presence of diabetes patients in the family, the presence of other risk factors (alcohol abuse, smoking, high blood pressure, obesity, high cholesterol, cardiovascular disease, etc.), diet and lifestyle (physical activity, harmful substances), presence of other past or accompanying diseases, medication, allergies, etc.
The doctor will then thoroughly examine you, looking for visible signs of both diabetes and risk factors for its development and complications (e.g. moisture and elasticity of the skin, state of protection, obesity, stretch marks, blisters, ulcers or signs of inflammation on the skin, etc.).
In addition to this initial examination, the doctor will measure the blood pressure and follow the pulsations of the major arteries in the body. If the information from the examination so far (presence of risk factors, presence of diabetes-specific symptoms or complications) suggests the presence of diabetes mellitus, the doctor will order the performance of a number of tests.
In the simplest terms, research can be divided into two groups:
- the first group – measures the level of blood sugar (glucose in the blood) by various methods and is crucial for the diagnosis of “diabetes mellitus”
- second group – determines the type, severity, and stage of the disease, the degree of involvement of the important organs, the development of complications, etc.