ŽIGA’S BLOG

Summer is the time when most people put away their long sleeves, hop on a bike or head to the mountains, and enjoy an ice cream in the sun. But for people with diabetes, it’s also a time to pay special attention to what’s happening in the body. Heat, humidity, increased physical activity, and changes in diet can significantly affect blood sugar levels.

Here are some key tips that can help you keep your blood sugar stable in the summer – and enjoy the season without unpleasant surprises.

1. How does heat affect blood sugar?

Heat can raise or lower your blood sugar, depending on several factors:

• Dehydration: the body loses more fluids, which can increase the concentration of glucose in the blood.

• Increased insulin sensitivity: heat can make the body absorb insulin faster (especially when using insulin pumps), which increases the risk of hypoglycemia.

• Changed metabolism: research shows that metabolism is slightly faster in warm weather – which can affect the breakdown of carbohydrates and the absorption of medication.

Practical insight:
A study published in the Journal of Diabetes Science and Technology (2012) found that extreme heat can affect the functioning of insulin pumps – especially at temperatures above 35 °C, where insulin loses stability after just a few hours.

2. Physical activity in summer: YES, but wisely

Summer invites us to move, but…

Exercising in the heat can speed up the effects of insulin or medication, which means a higher risk of hypo – especially if you’re exercising in the middle of the day or not well hydrated.

Recommendations:

• Best time for exercise: early in the morning.

• Drink water BEFORE activity – don’t wait until you’re thirsty.

• Check blood sugar regularly before and after exercise (and during, if you’re on a longer activity).

• Always carry fast-acting carbs (e.g., glucose, juice, dates).

3. What to eat in summer? Refreshing, light, and glucose-smart

Hot weather reduces appetite – and that’s completely normal. But it’s important not to forget about regular, balanced meals. In summer, choose foods that:

• hydrate the body,

• have a low glycemic index,

• are easy to digest.

Top summer picks for people with diabetes:

• Watermelon (in moderation, paired with a protein snack)

• Yogurt with flax seeds and blueberries

• Cold vegetable soups (e.g., gazpacho)

• Eggs, tuna, tofu – as protein sources

• Sugar-free lemonades with mint and ginger (or with added electrolytes)

FUN FACT:
The risk of nighttime hypoglycemia is higher in summer because the body cools down more at night and insulin may be released more slowly. If you were active in the evening, consider a small extra snack before bedtime.

Having diabetes in summer doesn’t mean you have to sit at home in the shade with a thermometer in hand. It simply means you need to understand how your body responds to heat – and adapt your activity, nutrition, and insulin accordingly. With the right approach, you can fully enjoy summer while keeping your blood sugar in check.

About the Author:

Žiga Papež is an ultra-endurance athlete and a type 1 diabetic. He is the founder of Slovenia’s largest diabetes platform, Sladek Lajf, through which he raises awareness about diabetes, healthy eating, and a high-quality lifestyle. At the same time, he actively fights against excessive sugar consumption and obesity.

Through educational content and personal experiences, he helps people understand how food affects the body, how to manage blood sugar levels, and how the right approach can improve overall well-being and physical fitness. His goal is to show that with knowledge and smart choices, we can overcome limitations and live a healthy, active, and more fulfilling life.