7 Surprising Factors That Can Affect Your Blood Sugar Levels

Discover unexpected influences on blood sugar and why people with diabetes must stay vigilant about these daily factors.

By Medha deb

Created on Sep 26, 2025

Discover unexpected influences on blood sugar and why people with diabetes must stay vigilant about these daily factors.

Managing diabetes requires more than just paying attention to food choices and medication. While carbohydrate intake and insulin are critical, a range of other daily factors can unexpectedly impact blood sugar (glucose) levels. Some causes may be obvious, but others are subtle or often overlooked. Understanding these will help you stay on top of your condition and avoid potential complications, even if you think you’re doing everything right. Here, we explore seven surprising things that can affect your blood sugar and explain how and why they matter for people with diabetes.

Stress
Steroids and Certain Medications
Hormonal Changes
Illness and Infections
Dehydration
The Dawn Phenomenon
Temperature Extremes
Frequently Asked Questions

1. Stress

Emotional or physical stress can cause blood sugar levels to spike, even without any dietary changes. The body responds to stress by releasing hormones such as cortisol and adrenaline, which prompt the liver to release glucose into the blood for a quick energy boost. This survival mechanism is useful in emergencies, but for people with diabetes, it can lead to persistently high blood sugar.
Chronic stress, like work pressures or ongoing anxiety, may create elevated glucose levels over time. Acute stress—from sudden trauma or pain—can trigger rapid spikes.

Chronic psychological stress can make diabetes harder to control.
Physical stress such as surgery, injury, or even intense exercise may cause fluctuations.
Learning to manage stress through relaxation techniques, therapy, or exercise can help moderate these effects.

2. Steroids and Certain Medications

Medications used for other health conditions can dramatically affect glucose levels. Steroids (such as prednisone) are notorious for increasing blood sugar because they cause the liver to produce more glucose. Other drugs, from hormones to certain diuretics, can also have similar impacts.

Steroid medications can quickly raise blood sugar; levels often return to normal after stopping the drug.
Niacin (Vitamin B3), prescribed for cholesterol, has been shown to modestly increase blood glucose.
Be aware of possible interactions: talk with your doctor before starting any new medication.

3. Hormonal Changes

Sometimes blood sugar is affected by changes in hormone levels completely unrelated to diabetes management. Common instances include:

Puberty: High levels of growth hormone, testosterone, estrogen, and cortisol during adolescence may increase insulin resistance, sometimes requiring higher doses of insulin.
Menstruation: Women may experience glucose fluctuations due to hormonal changes during their cycle.
Menopause: Changing hormone profiles can alter insulin sensitivity, complicating glucose management.

Life stages and hormonal shifts can prompt unexpected blood sugar changes, so adjust monitoring accordingly and consult your healthcare provider about trends.

4. Illness and Infections

Being sick—whether from a minor cold or a serious infection—can spike blood sugar, even without changes to your usual meal plan or activity levels.

When you’re ill, the body releases stress hormones (cortisol, adrenaline) to fight infection, which can cause the liver to release extra glucose.
Fever, viral illness, or even pain (acute or chronic) can prompt hyperglycemia.
Monitor blood sugar more frequently when sick, since it may require temporary medication adjustments.
Severe hyperglycemia during illness can raise the risk for dangerous complications, such as diabetic ketoacidosis.

5. Dehydration

Dehydration—not having enough water in your system—can drive blood sugar higher. Water is necessary for all metabolic processes, including the kidney’s role in excreting excess glucose.

Not drinking enough fluids leads to more concentrated blood, increasing measured glucose levels.
High temperatures, heavy sweating (during exercise or hot weather), vomiting, or diarrhea can worsen dehydration.
Even mild dehydration may affect blood sugar readings or worsen hyperglycemia symptoms.
Drink plenty of fluids, especially on hot days or during illness, to help keep levels stable.

6. The ‘Dawn Phenomenon’

Morning blood sugar spikes are common in people with diabetes, often caused by the “dawn phenomenon.” This refers to periods of elevated blood sugar between about 3 am and 8 am.

Early morning hormones (cortisol, glucagon, growth hormone) tell the liver to release glucose to prepare for the day.
Most people experience a slight rise, but those with diabetes may not have enough insulin to counter it.
If you notice high fasting numbers, talk to your doctor—medication timing and dosages may need adjustment.
Other causes for morning highs include insufficient insulin overnight or eating a carbohydrate-heavy bedtime snack.

7. Temperature Extremes

Hot or cold weather can impact blood sugar levels—sometimes in unexpected ways.

Heat can lead to dehydration, which raises the concentration of glucose in the blood.
Cold can make the body work harder (such as shivering), which may lower or sometimes raise glucose, depending on physical activity and other factors.
Newer research suggests mild cold exposure can improve insulin sensitivity in people with type 2 diabetes.
Keep insulin and supplies stored at recommended temperatures, as extreme heat or cold can affect potency and device accuracy.

Always monitor your blood sugar during periods of extreme weather, and make adjustments as needed to prevent dangerous highs or lows.

Quick Reference Table: Surprising Factors Affecting Blood Sugar

Factor	How It Can Affect Blood Sugar
Stress	Raises levels due to hormone release (cortisol, adrenaline)
Steroids/Medications	Raises levels by increasing liver glucose production
Hormonal Changes	May increase insulin resistance, cause fluctuations
Illness/Infections	Raises levels because of stress hormones and inflammation
Dehydration	Raises concentration of glucose in blood
Dawn Phenomenon	Raises morning levels due to hormone surges
Temperature Extremes	Heat raises through dehydration; cold can affect insulin sensitivity

Frequently Asked Questions (FAQs)

Q: Can stress really impact my blood sugar even if my diet is healthy?

A: Yes. Both emotional and physical stress prompt the release of hormones that increase liver glucose output, often leading to higher blood sugar levels even with a healthy diet.

Q: Why do steroids and certain medications cause blood sugar spikes?

A: Steroids stimulate liver glucose production and insulin resistance. Other drugs, such as niacin, can also have a direct impact. Always discuss new prescriptions with your healthcare provider.

Q: What is the dawn phenomenon, and how can I manage it?

A: The dawn phenomenon is a rise in blood sugar between 3 am and 8 am due to increased hormone activity. Management may involve adjusting insulin or medication timing, avoiding excessive evening carbs, and speaking with your doctor.

Q: How does dehydration affect blood sugar readings?

A: Dehydration raises blood sugar concentration due to lower blood volume. Ensuring adequate fluid intake can help keep glucose readings accurate and prevent dangerous highs.

Q: How do hormonal changes through puberty, menstruation, or menopause affect diabetes?

A: Hormonal changes can increase insulin resistance or otherwise change the body’s glucose metabolism, requiring close monitoring and sometimes temporary treatment adjustments.

Q: Should I worry about temperature when managing diabetes?

A: Yes. Hot and cold weather may directly or indirectly impact your blood sugar. Heat increases risk of dehydration, while cold could alter your body’s metabolic demands. Store insulin and testing devices properly for best results.

Q: What should I do if I notice unexpected spikes, even though I am following my plan?

A: Track any possible triggers—stress, illness, medications, dehydration—along with diet and activity. Monitor trends, and discuss sudden changes with your healthcare provider for potential adjustments.

Takeaway: Stay Vigilant for All Sources of Blood Sugar Change

The complexity of diabetes management means staying alert to a variety of factors, not just what you eat or how you exercise. Stress, medications, hormones, illness, dehydration, morning hormone surges, and the weather can all conspire to push your blood sugar up or down. By knowing and watching for these influences, you give yourself the best chance of maintaining control—and good health—over the long term.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

Read full bio of medha deb