Blood Sugar Level

Am I fit to fly? Is a common question a pilot may and should ask themselves before each flight to assess their fitness to fly. 'IMSAFE' is easy mnemonic covering aspects of human factors prior to each flight. Pilots must make sure all components are checked off before commencing flight, as they all have a somewhat effect on the blood sugar level.


[] 28 August 2012


The amount of glucose present in the blood of a human is referred to as the blood sugar concentration, or glucose level. In order for the body to have and produce energy, it needs glucose- a form of sugar. We get this glucose through our diet. Our body breaks down most of the food (fats and proteins) we eat down into glucose when required. The other is stored as carbohydrates or fats. When the body requires more glucose the stored carbohydrates or fats are broken down into glucose and is absorbed into the blood stream and is used by cells for growth and energy.[1]

Where does the Glucose come from?

There are two ways in which glucose can enter the blood stream: through the gut and from the liver.
The Gut: As mentioned above, the main source of glucose comes from meals. The meal is broken down and absorbed in the Upper intestine and is absorbed, partially in glucose form. This eventually enters the blood stream and contributes to the blood glucose count, furthermore increasing it.
The liver: The liver is the body's own mechanism of producing natural glucose. When the body is deprived of glucose, the individual may feel down because of the lack of energy. When the body does not receive any oral consumption of glucose the liver automatically makes its own glucose. However, the glucose consumption by the body is fast and when constantly starved the glucose in the bloodstream will drop fast.
It is important to note that the brain is dependent upon the presence of glucose in order to function. Therefore, low levels, or occasionally no levels, of glucose will affect the functioning of the brain. [6]

Units and Normal values in humans

Blood sugar level is expressed as millimoles per litre (mmol/l). The Normal blood sugar levels throughout the day should range from 4 to 8mmol/l. However they tend to be higher after meals and usually lowest in the morning.

The ideal values are:
• Before meals- 4 to 7mmol/l
• 90 minutes after a meal: Less than 10mmol/l
• At bedtime- Around 8mmol/l [3]


[] 30 August 2012


Hypoglycaemia can develop when the blood sugar levels drop too low. This is caused by the glucose in the body used up too quickly, glucose released into the bloodstream to slowly or too much insulin is released into the bloodstream. But the overall principal arise from an insufficient supply of glucose to the brain, resulting in impairment of function. Some common causes of low blood sugar levels are skipping meals, drinking alcohol and exercising more without eating. Pilots need to understand the symptoms as they can affect the ability of the pilot to fly safely. A drop in the blood sugar levels and can be felt by the pilot through the following symptoms: an increase in heart rate, faintness, trembling and shaking, cold sweating and nervousness. [1]


The pancreases plays a vital role in keeping the blood sugar the right levels, it secretes insulin (a hormone that reduces blood sugar) into the blood stream and controls the amount of glucose circulating in the blood stream. If insulin is ineffective, too much glucose will end up circulating the blood stream. This leads to a disease called diabetes, which if not recognised can cause severe illnesses . If diabetes is not efficiently treated it will lead to the damage of the small blood vessels causing blindness, kidney failure and heart attack. Diabetes can be controlled by the person's diet and medication but is an ongoing process. If a pilot has or develops diabetes it is difficult for them to maintain their pilot’s license. [1]

Religious fasting and flying

Due to religious beliefs some pilots may carry out fasting while continuing to fly. Fasting is a period of abstinence from all food or specific items. When pilots carry out fasting this can lead to low blood sugar and can cause the pilot to faint. This is a dangerous practice when flying and the pilot should not fly when fasting and carry this out during a different time other than flying.


  • Avoid skipping meals, or going for more than three hours without eating.
  • Eat meals at regular times because your body functions best on a regular schedule.
  • Increase the intake of food if you do more exercise.
  • If you have diabetes, follow your doctor's advice about diet, medicine, and exercise.
  • Do not drink alcohol without eating food. If you do drink without eating first, have only one or two drinks at the most.
  • If you have a history of hypoglycaemia, keep a snack or drink containing sugar with you at all times. Eat the snack as soon as symptoms appear. [4]

Managing blood sugar (glucose) levels

The following video shows how to manage your blood sugar levels. Learn what causes a rise in glucose and what you can do to set it right.

Video embedded from YouTube on 28 August 2012

Want to know more?

This page in Wikipedia offers more detailed information about the blood sugar.


  1. Ewing, R. (2003). Aviation Medicine and Other Human Factors for Pilots- 5th Edition. Old Sausage Publishers Limited.
  2. Wikipedia (2012). Blood Sugar. Retrieved August 28, 2012 from
  3. Blood Glucose Levels (2008).Retrieved August 28, 20012 from
  4. Hypoglycemia (2011).Insulin shock; Low blood sugar.Retrieved August 28, 20012 from
  5. YouTube (2012). Manage your blood sugar (glucose) levels. Retrieved August 28, 2012 from
  6. Diabeteshome (2001).Glucose. Retrieved August 30, 2012 from

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