Exam stress significantly raises blood sugar levels in medical students

Exam stress is associated with significant increases in blood sugar levels in medical students both during exams and the days leading up to them, according to new research being presented at the Annual Meeting of The European Association for the Study of Diabetes (EASD) in Milan, Italy (Sept 28 – Oct 2). The findings highlight the measurable metabolic impact of acute psychological stress.

As author Dr Jan Broz from Charles University and Motol University Hospital, Prague, Czech Republic explained, "Although average daily blood sugar levels did not significantly exceed the upper limit for healthy individuals, and are not dangerous in the short run, they do indicate that exam stress indirectly increases blood sugar levels. However, because medical students are exposed to examination stress for prolonged, repeated periods of time, often for months, this could well have a negative impact on their metabolic health."

He added, "To manage stress, students are advised to practice stress reduction techniques, ensure adequate sleep, eat balanced meals, provide regular physical activity, stay hydrated, and avoid excessive caffeine."

Studying medicine is generally considered highly demanding and is associated with substantial psychological stress. It is known that stress results in heart rate and blood pressure elevation. However, there has been little research into whether examinations create enough stress to cause measurable changes in blood glucose levels.

One possible explanation is that increased stress can raise levels of the "stress hormone" cortisol, which may contribute to higher blood glucose levels. Cortisol stimulates the liver to release glucose into the bloodstream, providing the body with a rapid source of energy during stressful situations, such as exams.

To investigate this further, researchers set out to assess whether examination-related stress in medical students was associated with changes in blood glucose levels.

The study included 22 healthy second-year medical students from Prague (13 women and 9 men), with an average age of 21 years and an average body mass index (BMI) of 21.9 kg/m².

The researchers used continuous glucose monitoring (CGM) to measure glucose levels every 15 minutes using a small sensor worn on the back of the arm. Monitoring began seven days before a biochemistry exam and continued until three days after the exam.

On the day of the exam, psychological stress was assessed using the standardized State-Trait Anxiety Inventory (STAI) questionnaire. Participants also reported factors that could influence glucose levels, including physical activity, food intake, and sleep.

The highest average daily glucose level was recorded on the day of the examination, at 5.72 mmol/L. This represented an increase of 0.37 mmol/L from 5.35 mmol/L on the fourth day before the exam (see graphs in notes to editors).

Subsequently, a decrease of 0.30 mmol/L was observed between the exam day and the following day (5.42 mmol/L).

Similarly, average glucose levels during sleep gradually increased in the days leading up to the exam, from 4.70 mmol/L on the seventh night before the exam to 4.93 mmol/L on the night before the exam.

Importantly, glucose levels during different parts of the examination-written test, break and oral examination-followed the expected pattern of stress, with the highest average level recorded during the written test (6.14 mmol/L).

The analysis also found significant correlation between stress levels reported in the questionnaire and glucose levels. For instance, students who reported feeling more stressed by the exam (scoring in higher percentiles on the STAI-X1 questionnaire) had a higher average glucose level prior to the exam day, followed by a sharper drop in these values after the exam.

Persistently or repeatedly 'slightly raised' glucose levels could shift an individual's usual blood glucose range and potentially contribute to the development of type 2 diabetes over time. In addition, stress hormones such as catecholamines and cortisol counteract the effects of insulin, and prolonged elevations in these hormones may contribute to insulin resistance through several biological pathways."

Natalia Michalcova, Author, Charles University and Motol University Hospital, Prague

She added, "Students experiencing exam stress should be encouraged to look after their health by maintaining healthy eating habits, staying physically active, and finding ways to manage stress. Our findings highlight the importance of helping students understand how psychological stress can affect the body, particularly those who may be at greater risk of developing diabetes."

The authors note several limitations, including that the study was observational, involved a small group of medical students and followed participants across a single examination. As a result, it cannot determine the specific causes of the elevated glucose levels. They add that larger studies with longer follow-up are needed to confirm these findings and establish causality, identify risk factors, and better understand the potential effects of stress on medical students.