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Common Causes, Symptoms, and a Chart of Low Blood Sugar Levels

Like high blood sugar, abnormally low blood sugar also needs prompt medical attention. Take a look at the low blood sugar levels chart presented in this article to check whether your levels have dropped slightly or drastically. This HealthHearty article contains normal and high blood glucose levels charts, too. Causes and symptoms of this abnormality are also explained in this article. Read on to know all this and more.
Leena Palande
Last Updated: Apr 9, 2018
The amount of sugar (glucose) present in blood can be measured with simple blood tests. The level of sugar in blood keeps on changing. Blood sugar is generally at its lowest level in the morning and its level drastically rises after each meal. Diet and physical exercise are the main factors that influence blood sugar levels. Abnormal fluctuations in blood glucose levels is one of the main symptoms of diabetes.
A decrease in blood sugar levels is also known as hypoglycemia, and it may occur in people with or without diabetes. For the latter group, the cause may either be an underlying disease or medications, or they may be having postprandial hypoglycemia or reactive hypoglycemia, which occurs 4 hours after consuming meals.
Types of Tests for Diagnosis
Usually, there are four types of tests used. These are explained as under.
Fasting Plasma Glucose Test (FPG)
This is done on an empty stomach. Meaning, a person must not consume food and liquid (excluding water) for at least 8 hours. Usually, this test is done in the morning.
A1C Test
This test doesn't require any fasting and is used to detect the blood sugar levels for the past 2 or 3 months.
Oral Glucose Tolerance Test (OGTT)
This test takes 2 hours to determine the sugar levels before and after drinking a sweet drink. This helps the doctors know how the body handles the digestion of glucose.
Random/Casual Plasma Glucose Test
This test is conducted when a person has severe symptoms of diabetes. It can be taken at any time without any preparation.
Normal Blood Glucose Levels Chart
The chart below explains the normal values of blood glucose in the body based on the type of test done for diagnosis.
Type of Test Blood Sugar Level
FPG 70 - 100 mg/dL
A1C Less than 5.7%
OGTT Less than 140 mg/dL
Random Plasma Glucose Below 125 mg/dL
High Blood Glucose Levels Chart
Category Fasting Sugar Minimum Value Fasting Sugar Maximum Value Sugar Value Before and After 2 Hours of Consuming Glucose
Normal 70 mg/dL 100 mg/dL Less than 140 mg/dL
Prediabetes 101 mg/dL 125 mg/dL More than or equal to 140 mg/dL
Established Diabetes More than 126 mg/dL - More than or equal to 200 mg/dL
Low Blood Sugar Levels Chart
Category Blood Sugar Level
Normal 70 - 100 mg/dL
Borderline Hypoglycemia 70 mg/dL
Fasting Hypoglycemia Less than 50 mg/dL
Please Note: The values mentioned above may vary from one laboratory to another. The ranges may also differ from one individual to another based on their overall health and other influencing factors. Kindly consult your physician for accurate interpretation of the results.
What Causes Low Blood Sugar Levels
The normal range of blood sugar is 70 to 100 mg/dL (milligrams per deciliter) in the morning (after fasting for at least 8 hours). Normally, if the level drops below 70 mg/dL, the person is said to suffer from hypoglycemia. The causes are mentioned as follows.
Hormone Imbalance
Hormones such as insulin, glucagon, epinephrine (or adrenalin), cortisol, and growth hormone, help maintain blood glucose at normal level. Dysfunction of glands such as adrenal glands, pituitary gland, pancreas, and liver can lead to serious fluctuations in glucose levels.
High doses of medicines that are used to control high sugar levels and wrong use of medicines can cause hypoglycemia. Use of certain medications such as beta blockers, quinine (used to treat malaria), aspirin, and monoamine oxidase inhibitors (a group of antidepressant drugs), can result in low blood sugar levels.
Consumption of alcohol without consuming enough and proper food can affect the function of the liver, causing low sugar in blood.
Starvation, fasting, or missed meals can seriously affect the level of blood sugar in children as well as adults. Food is necessary for the formation of glucose and energy.
Hyperinsulinemic hypoglycemia develops when insulin is produced by the body in an unnatural or excessive way. This condition leads to reactive hypoglycemia.
Liver and kidney disorders can affect the process of blood sugar regulation. Severe infections can be one of the major causes of low blood sugar.
Pancreas produces insulin and so, pancreatic tumors are one of the main causes of hypoglycemia without diabetes.
Other Causes
Adrenal abnormality, congenital defects, and pituitary disorders are some other causes.
What are the Symptoms
When the glucose levels go way too low, it may prove to be dangerous if necessary action is not taken on time. At times, a sudden drop may not even give out any alarming signs, and the person may faint, have a seizure, and in severe cases, may also go into a coma. Listed below are the possible symptoms one is likely to experience.
  • Blurred vision
  • Feeling hungry
  • Profuse sweating
  • Feeling panicky
  • Shivering
  • Rapid heartbeat
  • Weakness and fatigue
  • Headache
  • Tingling sensation
  • Inability to concentrate
Hypoglycemia Unawareness
There are some cases wherein one is unable to experience any symptoms of the decrease in blood glucose levels. While normally, during an episode, a person tends to wake up from sleep, people with hypoglycemia unawareness do not. This may be seen in those who have had diabetes for a long time, or who usually have low blood sugar levels in the body which has resulted in their inability to sense the alarming symptoms when hypoglycemia occurs.
Immediate Treatment Options
It is only under the guidance of a trusted healthcare provider, that a detailed treatment plan can be established after determining the cause and type of hypoglycemia one has. However, listed below are some immediate treatment measures that can be taken when one experiences severe symptoms of low blood sugar in the body.
Consume -
  • A tablespoon of sugar or honey
  • 3 to 4 glucose tablets
  • Half a cup of any fruit juice or regular soda
  • 5 to 6 pieces of hard candy
  • 1 cup milk
Constant monitoring of the glucose levels is a must to know if they have been restored to normal. This should be done after 15 minutes of eating the quick-fix foods. Another serving is recommended till the values are normal.
Disclaimer: The information provided in this HealthHearty article is meant for educational purposes only and should not be considered as a replacement for expert medical advice. Kindly consult your healthcare specialist as strict dietary and lifestyles changes are needed for prevention and treatment. These may vary from person to person.