For people with diabetes, maintaining stable blood glucose levels is a daily challenge. But did you know that the changing seasons can add another layer of complexity to diabetes management? From colder winters to sweltering summers, seasonal shifts can influence blood sugar in surprising ways. To dive deeper into this topic, we consulted Dr. Sabrina Rene, an experienced endocrinologist from Piedmont Healthcare, and reviewed recent studies to uncover how seasonal changes impact glucose levels and what you can do to stay in control.
How Seasonal Changes Affect Blood Glucose Levels
Recent research and expert insights confirm that seasonal variations can significantly affect blood glucose levels, particularly for those with type 1 and type 2 diabetes. According to a 2023 study from Dartmouth, published in Science Advances, seasonal patterns in glucose control are evident when analyzing data from continuous glucose monitors (CGMs). Here’s what we know:
Warmer Months (April to August): During spring and summer, people with diabetes tend to maintain healthier blood glucose levels. The Dartmouth study found that patients spent more time within the target glucose range (70–180 mg/dL) during these months, likely due to increased physical activity and better insulin sensitivity. Warmer weather encourages outdoor activities like walking or gardening, which help the body use insulin more effectively.
Colder Months (November to February): In contrast, glycemic control often worsens during fall and winter. The study showed a significant decrease in time spent in the target range, with the largest declines around holidays like New Year’s Day and Christmas. Dr. Rene explains, “In colder months, people are less active, and holiday gatherings often involve high-calorie, sugary foods, which can spike blood glucose levels.” Additionally, cold weather triggers the release of stress hormones like cortisol, which can reduce insulin sensitivity and raise blood sugar.
Holiday Impact: The Dartmouth study highlighted that holidays amplify glucose fluctuations, especially for those with already poor glycemic control (less than 55% time in target range). Festive meals, stress, and disrupted routines contribute to these spikes.
Extreme Temperatures: Both extreme heat and cold can pose challenges. A 2018 study from Gavin Publishers notes that high temperatures can lead to dehydration, concentrating glucose in the blood and causing hyperglycemia. Conversely, cold weather can slow insulin absorption due to reduced blood flow to extremities, making it harder to manage blood sugar.
Expert Insights from Dr. Sabrina Rene
Dr. Rene emphasizes that seasonal changes affect not only blood glucose levels but also diabetes management tools. “Extreme temperatures can impact the accuracy of glucose meters and the stability of insulin,” she says. “For example, leaving insulin or test strips in a hot car or freezing temperatures can degrade them, leading to inaccurate readings or ineffective treatment.”
She also points out the role of lifestyle factors:
Winter Challenges: “In winter, people tend to stay indoors, reducing physical activity. This, combined with holiday eating, can lead to weight gain and insulin resistance,” Dr. Rene notes. The body’s natural response to cold—releasing stress hormones like cortisol and adrenaline—can further elevate blood sugar.
Summer Risks: In summer, dehydration is a major concern. “Dehydration can cause blood glucose to become more concentrated, leading to higher readings,” she explains. For those on insulin, dehydration can also reduce the body’s ability to absorb it, complicating glucose control.
Psychological Factors: Seasonal changes can affect mental health, which in turn impacts glucose levels. A 2020 study in Scientific Reports found that perceived sugar intake (even if inaccurate) can influence blood glucose levels in people with type 2 diabetes, highlighting the role of psychological factors like stress or holiday-related anxiety.
Recent Studies on Seasonal Glucose Variations
Several studies provide deeper insights into how seasonal changes affect glucose levels:
Dartmouth Study (2023): This study analyzed over 91,000 days of CGM data from 137 patients, primarily with type 1 diabetes. It found that glycemic control was worse in winter, with November to February showing lower time in range (TIR) compared to April to August. The study also noted daily and weekly variations, with better glucose control during workweek hours (9 a.m. to 5 p.m.) compared to weekends, suggesting that structured routines help stabilize blood sugar.
2011 Study on Population Averages: A study published in PubMed examined three years of data from 3,243 diabetes patients in Israel. It confirmed that winter glucose levels were consistently higher than summer levels, with a median winter-summer difference of 8 mg/dL. This pattern was not due to occasional spikes but reflected a general seasonal tendency.
Climate and Diabetes (2023): A study in PMC explored the link between climate change and diabetes, noting that higher ambient temperatures are associated with increased insulin resistance and dysglycemia. This suggests that long-term climate trends could exacerbate seasonal challenges for diabetes management.
Practical Tips for Managing Glucose Levels Year-Round
Dr. Rene offers actionable advice for navigating seasonal changes:
- Monitor Frequently: “Test your blood sugar more often during seasonal transitions or extreme weather,” she advises. Continuous glucose monitors (CGMs) are particularly helpful for real-time tracking, especially in hot or cold conditions when fingerstick readings may be less reliable due to poor circulation.
- Protect Your Supplies: Store insulin, test strips, and glucose meters at room temperature (avoid extremes below 40°F or above 86°F). Use insulated cases or car coolers when traveling to prevent degradation.
- Stay Hydrated: In summer, aim for 7–8 glasses of water daily to prevent dehydration. In winter, consider warm herbal teas or fenugreek water (soaked overnight) to support hydration and stabilize blood sugar.
- Maintain Activity: In winter, opt for indoor exercises like stair climbing, yoga, or gym workouts to keep active. In summer, choose air-conditioned spaces for workouts to avoid heat exhaustion. Aim for 150 minutes of moderate activity per week, as recommended by the American Diabetes Association.
- Adjust Diet for Holidays: During festive seasons, balance high-carb meals with fiber-rich foods (e.g., vegetables, whole grains) and lean proteins to minimize glucose spikes. Dr. Rene suggests keeping glucose tablets handy for unexpected lows.
- Manage Stress: Stress from holiday gatherings or seasonal changes can elevate cortisol and blood sugar. Practice stress-reduction techniques like meditation, deep breathing, or light exercise to maintain glycemic control.
- Consult Your Doctor: If you notice persistent glucose fluctuations, consult a diabetes specialist. Dr. Rene emphasizes, “Personalized care is key. Your doctor can adjust insulin doses or recommend medications like GLP-1 receptor agonists, which may help stabilize glucose and reduce cardiovascular risk.”
Special Considerations for Vulnerable Groups
The Dartmouth study highlighted that young adults (ages 19–34) are less proficient at managing blood glucose, possibly due to the transition to self-care without parental oversight. Additionally, women with a history of gestational diabetes or those with pre-diabetes may face heightened risks during seasonal shifts, as prolonged pre-diabetes can exacerbate insulin resistance.
Dr. Rene advises these groups to be extra vigilant: “Young adults and those with pre-diabetes should prioritize regular check-ups and CGM use to catch fluctuations early.”
The Bigger Picture: Climate Change and Diabetes
Beyond seasonal changes, long-term climate trends pose additional challenges. A 2025 study in ScienceDirect found that heatwaves and temperature fluctuations increase insulin resistance, particularly in vulnerable populations like low-income individuals or those exposed to air pollution. This suggests that as global temperatures rise, diabetes management may become even more complex, emphasizing the need for proactive strategies.
Conclusion: Take Control of Your Diabetes Year-Round
Seasonal changes can indeed affect your glucose levels, but with the right strategies, you can stay ahead of the curve. Dr. Sabrina Rene’s insights, combined with recent research, highlight the importance of frequent monitoring, protecting diabetes supplies, staying active, and managing stress and diet. By understanding how winter, summer, and holidays impact your blood sugar, you can work with your healthcare team to maintain optimal control.
For personalized guidance, consult a diabetes specialist or endocrinologist, and consider using tools like CGMs to track your glucose trends. Stay proactive, stay hydrated, and keep your diabetes management plan adaptable to the seasons. Your health is worth it!