Fasting blood sugar and its role in diabetes management

True to its name, fasting blood sugar refers to your blood sugar level after a considerable period of not eating or drinking anything except water. The fasting blood sugar test is one of the most frequently employed methods to diagnose diabetes or manage the condition. You will need to fast for a minimum of eight hours for this test. Consuming any food or drink in between will absorb it in your bloodstream and cause deviations in the reading. Dive into this article to know what is the fast blood sugar normal range and when it reaches dangerous levels.

The factors that affect fasting blood sugar readings are:

  • Contents of the previous meal
  • Portion consumed
  • Insulin sensitivity of the body

Why are fasting blood sugar readings so important?

The chief reason to take a fasting blood sugar test is an early diagnosis of diabetes. It is also essential for the therapeutic management of diabetes for someone already diagnosed with it. This test shows how capably your body draws the glucose from your bloodstream into cells. Since you are on an empty stomach for eight hours before the test, there is less room for inaccuracy.

Fasting triggers glucagon secretion. Glucagon increases the blood glucose level. If your insulin production is normal, this increased glucose level gets balanced by insulin action. However, if your blood sugar levels remain high even after fasting for eight hours, you may have insulin resistance. Therefore, fasting blood sugar is a potential indicator of how well your body responds to insulin and manages glucose absorption. It also acts as a signal to warn you if your body is reaching dangerous blood sugar levels.

How does a fasting glucose test work?

The steps involved in a fasting sugar test are as follows:

  • Sterilise the area inside your elbow.
  • Tie a band around your upper arm to make the veins more visible.
  • Insert a needle into the vein and draw the blood.
  • Send the blood sample to the laboratory for testing and wait for the results.
  • This blood sample will be used to test for the glucose level in your blood.
  • Postpone taking antidiabetic medications until after the test sample is drawn.

Things you need to know about fasting before a blood test

Remember these points while you prepare for a fasting blood sugar test.

  • Fast at least 8-12 hours before the test. Fasting overnight is the best option.
  • Avoid smoking, chewing gum or exercising hours before the test.
  • Do not eat or consume any liquid other than water before the test.
  • Reschedule if you have mistakenly consumed anything other than water before the test.
  • Carry a snack with you to consume right after the test.

Normal fasting blood sugar levels for a person without diabetes

The table below gives details of the fast blood sugar normal range for individuals without diabetes:

For children aged below 6 80-180 mg/dL
For children aged between 6 and 12 90-180 mg/dL
For adolescents (13-18 years) 90-130 mg/dL
For adults (above 18 years) 90-125 mg/dL

Fasting blood sugar levels in individuals with diabetes

Now that you know about the fast blood sugar normal range, let us look at the readings for a person with diabetes.

Prediabetes 100-125 mg/dL
Diabetes 126 mg/dL or higher
Dangerously low blood sugar Below 50 mg/dL
Dangerously high blood sugar Above 250 mg/dL

Effects of alarming blood glucose concentrations

When the blood sugar levels are higher than normal, it leads to hyperglycemia. Symptoms include fruity breath, drowsiness, nausea, vomiting, confusion and dry mouth. When blood sugar levels are lower than normal, it leads to hypoglycemia. Symptoms include profuse sweating, shakiness, rapid heartbeat, irritability, dizziness and extreme fatigue.

Both hyperglycemia and hypoglycemia need immediate attention. Aim to bring the sugar levels closer to the normal range. Failure to do so may result in dangerous blood sugar levels that lead to medical emergencies. A blood sugar reading of more than 250 mg/dL or less than 50 mg/dL is considered dangerous enough to cause life-threatening complications.

  • Blood sugar levels above 300 mg/dL may lead to diabetes-induced ketoacidosis.
  • Extreme hyperglycemia (blood glucose levels above 600 mg/dL) can cause the hyperosmolar hyperglycemic syndrome.
  • Sugar levels below 50 mg/dL can induce the body to go into hypoglycemic shock and even coma.

Can COVID-19 affect blood sugar levels?

In the case of undiagnosed prediabetes, COVID-19 can lead to dangerous blood sugar levels. Your immune system gets compromised due to COVID-19. It causes a sudden decline in the production of insulin-secreting beta cells in the pancreas. This condition results in hyperglycemia, and it may become permanent. Maintaining an ideal weight, moderate physical exercise and healthy eating can reverse the effects.

Treating dangerously high blood sugar

If your blood sugar levels cross 250 mg/dL, take a urine ketone test immediately. If the result is positive, contact your healthcare provider. The treatment is usually along the following lines:

  • Fluid replacement (through veins) dilutes the excessive sugar in your blood.
  • Electrolyte transfusion keeps your heart, muscles and nerve cells functioning normally.
  • Insulin therapy neutralises the build-up of ketones in your bloodstream.

Treating dangerously low blood sugar

If your blood sugar levels fall below 50 mg/dL, it may cause disorientation and difficulty swallowing. In such cases, the following treatment options are available:

  • Glucagon injections induce your liver to release stored glucose. The glucagon hormone immediately raises blood sugar levels.
  • Glucagon nasal powder is more fast-acting than injections.
  • Administering intravenous dextrose injections increases the concentration of water and carbohydrates in your bloodstream.

Managing blood sugar levels in diabetes

One of the most crucial aspects of diabetes control is not to let your body reach dangerous blood sugar levels. This is possible through regular exercise, proper diet and taking timely medications for diabetes. Your doctor may recommend frequent fasting blood sugar tests to monitor your blood sugar levels and suggest changes in the treatment plan. Keeping your glucose levels within the recommended range is the primary aim of diabetes management.

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