Fall into Stable Blood Sugars: Adapting to Seasonal Shifts

As summer winds down and the crisp air of autumn sets in, those of us managing Type 1 Diabetes face unique challenges—and opportunities—to keep our blood sugars steady. Seasonal shifts can affect everything from insulin sensitivity to meal timing, exercise routines, and even the foods we crave. Drawing on both science and my own experience, this post is meant as a comprehensive guide to help you transition smoothly into fall and maintain stable glucose control. Not all of these things WILL happen or ARE helpful, but some of them could be game changing! 

1. Embracing the Season: Why Fall Demands a Fresh Approach

Autumn brings cooler temperatures, changing daylight hours, busy back-to-school schedules, and an abundance of seasonal produce. Each of these factors can influence your blood sugar:

• Temperature affects insulin sensitivity.
• Daylight saving shifts your circadian rhythms, altering meal and insulin timing.
• Routine changes—kids back in school, new work schedules—impact meal patterns and stress levels.
• Fall flavors (apples, squash, pumpkins) introduce new carb-counting challenges.

Recognizing these shifts allows you to anticipate changes and adjust proactively rather than reactively.

2. Temperature & Insulin Sensitivity

Cooler Days, Increased Sensitivity

Studies show that colder temperatures can enhance insulin sensitivity, meaning your insulin works more effectively to lower blood sugar. You may notice:

• Steadier post-meal glucose curves.
• Higher risk of hypoglycemia, especially overnight.

Action Steps:

• Review basal rates: Consider a 5–10% reduction in basal insulin on consistently cool days.
• Monitor closely: Check blood sugars before bed and early morning for unexpected lows.

Warm Spells & Resistance

Autumn often includes warm days too. Heat can increase insulin absorption at infusion sites, but it can also promote inflammation, potentially raising blood sugars.

****REMINDER: you might experience the exact opposite in your blood sugar due to weather, that’s okay. Rely on your body’s trends primarily. 

Action Steps:

• Rotate sites frequently: Avoid applying sites to areas bound to get hot (under heavy clothing).
• Adjust bolus timing: If you spike after meals in warm weather, try delaying your bolus by 5–10 minutes.

3. Daylight Saving & Circadian Rhythms

When clocks “fall back,” our internal clocks can take days to adjust. Circadian misalignment can alter:

• Insulin sensitivity peaks (often higher in early morning).
• Meal timing (later breakfasts or dinners).
• Sleep quality, which influences blood sugar regulation.

Action Steps:

• Gradual shifts: In the week leading up to DST, shift meal and bedtime by 10–15 minutes each day if you want a seamless transition. 
• Consistent pre-bolus windows: Maintain your usual pre-bolus timing relative to meals, even if the clock changes.
• Extra checks: Test before bed and upon waking for a few days post-DST.

4. Back-to-School Routines & Stress

September often heralds a return to school and work routines, bringing both structure and stress. Stress elevates cortisol, which can spike blood sugar.

Action Steps:

• Morning check-ins: Test blood sugar when waking and before school/work to set a stable foundation.
• Scheduled snacks: Carve out mid-morning and mid-afternoon snack breaks if needed—pre-portion carbs to prevent surprises.
• Stress management: Incorporate 5-minute mindfulness or breathing exercises before high-pressure tasks.

5. Fall Produce & Carb-Counting Challenges

Autumn’s bounty offers delicious variety but also carb-counting puzzles:

• Apples & Pears: One medium apple ≈ 25g carbs.
• Winter Squash (butternut, acorn): 1 cup cooked ≈ 15g carbs.
• Pumpkin: ½ cup canned ≈ 12g carbs; beware sugar-spiced recipes.

Action Steps:

• Weigh & log: Use a food scale for new foods until you know their carb count.
• Combine macros: Pair starchy vegetables with protein/fat (e.g., roasted squash with chicken) to blunt spikes.
• Recipe swaps: Substitute half the regular flour in muffins with almond flour to lower carbs.

6. Basal & Bolus Adjustments

Fine-tuning both basal and bolus insulin is crucial for seasonal transitions.

Basal Tweaks

• Cool nights: Reduce basal by 5–10%.
• Warmer days: Monitor for resistance; consider a slight increase if you see persistent highs.

Bolus Timing

• Dense fall meals (stews, casseroles) digest slowly. Split your bolus: half upfront and half 1–2 hours later.
• Quick fall carbs (apple juice, sweetened drinks) still require standard pre-bolus timing (10–20 minutes before).

7. Hydration: Cold Doesn’t Mean Quench-less

Hydration often dips as temperatures fall, but staying hydrated remains critical for blood sugar stability:

• Aim for 8–10 cups of water daily, even if you don’t feel as thirsty.
• Add flavor with cinnamon-steeped water or a splash of unsweetened apple juice.
• Monitor for concentrated urine (darker color), a sign you need more fluids.

8. Fall Fitness: Adapting Exercise & Insulin

Changing seasons shift your activity patterns:

• Outdoor workouts: Cooler weather may prompt longer runs or hikes. Lower basal by 20–30% 30–60 minutes before prolonged cardio.
• Indoor classes: If you shift to gym workouts, track how each affects your glucose differently from outdoor exercise.
• Holiday prep: Begin mindful carb and insulin tracking before October’s holiday season to avoid last-minute chaos.

9. Preparing for Holidays & Gatherings

Autumn previews the busy holiday season. Early planning prevents carb surprises:

• Recipe testing: Try holiday recipes at home first—log carb counts and adjust doses.
• Portion control tools: Bring your own measuring scoop or plate divider to potlucks.
• Pocket snacks: Carry a low-carb snack in case options are limited.

10. Mindset & Self-Compassion

Seasonal changes can feel overwhelming. Remember:

• Small adjustments matter. A 5% basal tweak or a 10-minute pre-bolus shift can stabilize days.
• Validate your efforts. Fall brings chaos; adapting is a win.
• Celebrate resilience. Every day you stay in range despite the shifts is a victory.

Quick Summary: Autumn affects T1D management: cooler temps change insulin sensitivity, daylight savings shift rhythms, back-to-school stress spikes cortisol, and fall foods challenge carb counting. Tweak basals, pre-bolus wisely, stay hydrated, and plan for holidays to keep your sugars stable.

Diabetes is tough, but so are you. So remember, you’ve got this.

Stay fun,

Madi Cheever, MPH, RD, LDN, CHES
Type One Type Fun

‼️DISCLAIMER: although I am a healthcare professional, this post is not intended to be medical advice. This is simply me sharing some of what I know, but your body may not respond in this way so please make sure you are chatting with your diabetes educator and/or doctor first ‼️ or bring me onto your care team 😘