Metabolic Health

Random Glucose Testing - When To Test & Types

Reviewed by

Shifa Fathima

 What is Random Glucose Testing?

For people suffering from diabetes, it is imperative to keep a check on their glucose levels at random intervals of time. Random Glucose Test (RBS) is a test that evaluates the glucose level or amount of sugar flowing through the body at any given moment. Random Glucose Testing is extremely useful for patients with severe and prolonged diabetic issues. 

Random Glucose Testing is said as “Random” because the test is performed outside any scheduled timeframe, and the observed results are instantaneous. It is of the utmost importance to keep checking the glucose levels at random intervals. This helps the person suffering from diabetes to control the blood glucose levels.

      Table 1: Various tests indicating the blood glucose level for Diabetic, Prediabetic, and Normal.

What is diabetes?

Diabetes is a disease that affects the ability of the body to secrete insulin from the pancreas. Insulin hormone is vital as it regulates glucose uptake in the cells. Irregular insulin secretion causes a greater concentration of glucose and thus the high blood glucose levels in diabetic patients. The diagnosis is usually made by testing the glucose levels at random intervals of time. This form of diabetes is called Diabetes Mellitus. Diabetes mellitus is a chronic disease affecting more than half of the human population. Primary organs like the heart, kidney, eyes, and nerves are affected by this disease.

  • The normal concentration of blood glucose level is considered as 100 mg/dL.
  • Any blood glucose level more than 200 mg/dL is considered diabetic.
  • Blood glucose level from 140 mg/dL to 200mg/dL is considered prediabetic, meaning that the patient is prone to develop diabetes.

Another form of diabetes, like the diabetes insipidus, results in an imbalance of fluids in the body due to hyposecretion of antidiuretic hormone (ADH). However, Diabetes Insipidus is less prevalent than Diabetes Mellitus.

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When to go for Random Glucose Testing?

Random glucose testing can be done at any time. Patients who are diabetic need to monitor their blood glucose levels from time to time to keep themselves healthy. Random glucose tests should be done if you feel these symptoms.

  • Blurred vision
  • Sudden palpitation
  • Feeling extremely tired suddenly
  • Feeling nauseous

Other symptoms of diabetes also include

  • Weight Loss
  • Feeling of thirst and frequent urination
  • Fatigue
  • Slow healing of wounds and difficulty in blood clotting

What are the other types of Glucose Testing?

Diabetes is an extremely complex disease that affects various vital organs, and treating it is not easy, considering if the patient has other complications and diseases. Moreover, many medicines also have side effects which contribute to the overall disease. Comorbidity is a real issue when it comes to the treatment of diabetes. As a result, only random glucose testing is not enough to understand and treat the disease.

Other tests include A1C Test, Fasting Blood Sugar Test, Oral Glucose Tolerance Test, Glucose Screening Test.

Fasting Glucose Test

A fasting glucose test is a form of testing glucose levels in the body. It is tested early in the morning, right after waking up and before having any food or drinks. The idea of this test is to check the blood glucose level before any intake of food.

For the preparation of the test, it is mandatory not to have any food or drink except for water for 8 to 12 hours.


  • Fasting for 8 to 12 hours is mandatory
  • The test is usually performed early in the morning.
  • The doctor will clean the elbow and the arm region, with 70% alcohol for sterilisation purposes, from where the blood will be drawn.
  • An elastic band will be fastened above the arm to initiate swelling of the vessels.
  • Blood is drawn into a vial or syringe depending on the required blood volume for the tests.
  • Then the needle is then removed, and a band-aid is placed on the puncture site.
  • Then the needle is removed and a band-aid is placed on the puncture site.
  • The blood is sent to pathology labs for testing.

Read more about the fasting blood sugar level.

Oral Glucose Tolerance Test

Oral Glucose Test is done to test the different types of diabetes in a patient. The test is done to monitor the acceptance of glucose by the body. OGTT is done to find if the patient has


  • The patient needs to fast for at least 8 hours before the conduction of the test.
  • The patient then is asked to drink 8 ounces (237 millilitres) of a glucose solution containing 3.5 ounces (100 grams) of sugar.
  • Then after 2 hours, a blood glucose test is done to check the sugar uptake capability of the body.


For Type 2 diabetes

  • A normal blood glucose level is lower than 140 mg/dL (7.8 mmol/L).
  •  A blood glucose level between 140 and 199 mg/dL (7.8 and 11 mmol/L) is considered prediabetes. The patient has a risk of developing diabetes.
  • A blood glucose level of 200 mg/dL (11.1 mmol/L) or higher may indicate diabetes.

For Gestational Diabetes

  • A normal fasting blood glucose level is lower than 95 mg/dL (5.3 mmol/L).
  • One hour after drinking the glucose solution, blood glucose level is greater than 180 mg/dL (10 mmol/L).
  • Two hours after drinking the glucose solution, the blood glucose level is greater than 155 mg/dL (8.6 mmol/L).
  • Three hours after drinking the glucose solution, the blood glucose level is greater than 140 mg/dL (7.8 mmol/L).


Why is my blood sugar high in the morning but normal all day?

Our body goes through hormonal changes while asleep, especially at night. This incident happens because the body increases the body glucose level while we are sleeping. It is easier for the body to wake up and start functioning as glucose is a polysaccharide that provides energy to the body to sustain vital functions. This is why blood sugar levels are higher in the morning than all day, irrespective of whether anyone has diabetes.


Diabetes is a very common yet serious disease, though with the right medications and monitoring it can be kept under control. Thus, it is always best to remain diabetes free and ensure a proper lifestyle, healthy food and exercise to stay away from diabetes. Also read how diabetes home test works and it's accuracy.

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