2.4. Blood Sugar Measurement

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“You don’t want to eat such a sweet granny, don’t you? Your blood sugar will skyrocket.”


A blood sugar (glycaemic) test is performed primarily for the diagnosis of diabetes, but glucose levels should also be monitored in healthy people.


The level of glucose in the blood needs to be examined:

   In the case of any symptoms of hypoglycaemia or hyperglycaemia
   Routinely – as a part of a laboratory test, especially for people at risk of developing diabetes (in people over 40 years of age, overweight or obese, with a genetic risk of diabetes);
   Regularly – people suffering from diabetes measure sugar level even several times a day;
   Diabetics test their blood glucose levels at home using a glucose meter.

Glycaemic test with a home glucose meter is not a diagnostic result. The test should be performed in a laboratory. The result on a household glucose meteris vulnerable to a measurement error of up to 15% of the result (ISO standard ISO 15197:2015).


Glucose testing can be performed while:

   Fasting – do not eat or drink anything except water 8 hours before the test
   After a meal – a post-meal glycaemic test is performed 2 hours after the meal (e.g. at home, using a glucose meter)
   At any time – a random test of blood glucose can be performed at any time, it is not necessary to fast – an incorrect result of the sugar level does not constitute the basis for the diagnosis of diabetes. In such a case it is necessary to conduct further tests (fasting sugar test; oral glucose tolerance test)

Blood glucose levels – the norm

Diabetes is diagnosed based on glycaemia exceeding the norm in a fasting blood sugar test (double measurements), in the oral glucose tolerance test (OGGT).

Normal blood glucose result ranges between 70 and 99 mg/dl. In the case of a higher result (126 mg/dL or more), the test should be repeated several days later.

Venous blood glucose levels:


Oral glucose tolerance test (OGGT):



Low/high blood sugar –causes and symptoms
Low level of sugar in blood – causes

   Undiagnosed diabetes
   Food poisoning – with vomiting and diarrhoea
   Intense physical effort
   Some weight loss diets (not enough carbohydrates in the diet)
   Consumption of large amounts of strong alcohol
   Intake of larger portions of simple carbohydrates (with reactive hypoglycaemia)
   In diabetics: providing too much insulin, skipping a meal, eating too little

Symptoms of hypoglycaemia

   Early symptoms: feeling hungry, nausea, weakness, paleness, dilated pupils, anxiety, sweating (so-called cold sweat), shaking hands
   Severe hypoglycaemia: orientation disorders, speech disorders, convulsions, coma

High level of sugar in blood – causes

   Undiagnosed diabetes, insulin resistance
   Pancreatic disease (pancreatitis)
   Post-traumatic stress
   Cushing’s syndrome
   Endocrinologic diseases
   In diabetics: poorly treated diabetes (e.g. incorrect insulin doses, a skipped dose)

Symptoms of hyperglycaemia

   Heavy urination
   Increased thirst
   Dry mouth
   Feeling unwell, weak, sleepy
   Blurred vision
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