Effects of Low Blood Glucose on Pilot Performance

Would skipping breakfast adversely impact on flying performance?

Breakfast is the most important meal of the day. The research carried out by Johnson, Carlson, Veverka & Self (2007) was to experiment if skipping breakfast would adversely impact flying performance. This article provides a meta-analysis on the relevant results.

Illustration 1 shows, the difference in the change of blood glucose levels between the consumption of different carbohydrate condition drinks. Pilots who consumed Drink A with the high carbohydrate condition showed a 61% more blood glucose value than Drink B which contained a low carbohydrate.

Illustration 1 Comparison of change in blood glucose levels between drink conditions
Blood Glucose Value (mg/dl)
Mean StdDev
Drink A 37.62 26.03
Drink B 14.5 8.72

Both sets of data had a large standard deviation value which indicated there was a large amount of variation in the participant’s reaction to the different carbohydrate drinks; the standard deviation value was also affected by an extremely low outlier from some of the participants.

Illustration 2 Comparison of flight simulator data by drink conditions
Error Numbers Wings Level (sec) Initial Input (sec)
Mean StdDev Mean StdDev Mean StdDev
Drink A 2.75 0.89 11.26 1.33 0.93 0.18
Drink B 2.5 0.93 12.78 5.79 1.08 0.51
Two Tail P Value 0.59 0.48 0.45

From Illustration 2 and Illustration 3, it showed that the flight simulator and spatial disorientation test results were very similar, even though participants consumed different carbohydrate condition drinks. Only a very minor difference appeared to the participants who consumed the lower carbohydrate drink, which indicated reaction times to wings level and initial input were 13% slightly slower. This was not very significant in real-life terms as the differences between the test results were less than one second.

The Two tail P value results from Illustration 2 & 3 showed that at (p < 0.05) significant level for this research, all p values calculated is considered to be not statistically significant.

Illustration 3 Comparison of spatial disorientation data by drink conditions
Trial 1 (sec) Trial 2 (sec) Trial 3 (sec)
Mean StdDev Mean StdDev Mean StdDev
Drink A 29.0 5.42 28.0 6.18 26.88 3.79
Drink B 25.25 6.88 30.0 7.05 27.38 7.25
Two Tail P Value    0.25 0.56 0.87


Overall the test results indicated that there was no statistically significant difference ( p<0.05) in the consumption of different carbohydrate conditions drinks on the performance of the participants in the morning period.


Research approach

  • This was an exploratory study the effects of low blood glucose on pilot performance.


  • A sample of 8 individuals who had obtained private pilot license through the United States Air Force Academy flight screening program participated in the research. There were six males and two females with a mean age of 21.4 and a standard deviation of 0.90.
  • All participants were tested for phenylketonuria, pre-existing medical conditions and for any condition related to glucose intolerance.
  • Participants were also instructed to not use any over the counter cold/flu medications or alcohol for at least 36 hours preceding the experimental trials.


  • This research was conducted using a cross-over double-blinded design. Participants were provided with alternative low and high carbohydrate drink conditions and then performed a series of different tests (unusual attitude recovery and susceptibility to spatial disorientation).


Dependent Variables (DV)

  • Unusual Attitude Recovery - Error Numbers, Wings Level and Initial Input time.
  • Spatial Disorientation - Time duration of the self-illusory motion.

Independent Variables (IV)

  • High Carbohydrate condition drink: Drink A
  • Low Carbohydrate condition drink : Drink B


  • Participants were asked to only consume water after 1900 hours before testing and report at 0700 the following morning. Upon arrival, fasting conditions were validated.
  • Using the cross-over design, participants consumed either drink A or B on the first trial and then after seven days the opposite drink in the second trial.
  • Participants then had to wait a one hour period after consuming the drink.
  • Participants then had to complete a standardised flight performance tasks using F-PASS. A number of unusual attitudes recovery scenarios were presented which error numbers for roll reversal, time to for initial stick input and straight & level were recorded.
  • The second test, participants used a GAT II for the self-illusory motion test. Three trials were conducted in which the time when the participants felt they were no longer spinning were recorded.

Data analysis

  • The SAS software version 8.2 was used in the data analysis process. Results obtained were calculated for its mean and standard deviation.
  • A paired T-Test was used to compare blood glucose levels between drinks as well as flight simulator and spatial disorientation data. Refer to Illustrations 1,2 and 3.Flight simulator and spatial disorientation were analysed using the two-tails test.
  • (p < 0.05) significant level was chosen for this research.

Generalization potential

  • The sample size of only 8 participants participating in the research was low. This may have prevented detecting any statically significant in the research.
  • The process of glucose can vary between people and a larger number of participants could of possibly provided with a more variability in the data so the expected results from previous research findings could of been expected.
  • Even though this research was to carried out in the morning period because this is when the concentration of blood glucose is at its lowest, the time period could of been extended throughout the day to see the overall effects on different levels of blood glucose effects on the performance of pilot's. This is to get a better result expected from previous studies.
1. Johnson, O.C., Carlson, J. B., Veverka, D.V., Self, B.P. (2007) Effects of low blood glucose on pilot performance. United States Air Force Academy, Department of Biology, Colorado, 80840 +++ Notes +++
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