Diabetes in summer and while traveling – What you should know

By Julia Becker · Updated: May 2026 · Reading time approx. 6 minutes

Sun, warmth, vacation. And of course, diabetes comes along in the luggage.

Summer with diabetes brings some special considerations that people with both type 1 and type 2 diabetes should keep in mind. Temperatures above 30 degrees, changed daily routines, outdoor activity, and travel affect blood sugar levels more than you might think. Here you'll find the most important tips for a safe and relaxed summer with diabetes, with a little wink and no heat meltdown.

1. Insulin and heat: not a good combination

Insulin is sensitive to temperature. The package insert states how warm insulin may become, and this varies depending on the product. For example: A common rapid-acting insulin should be kept unopened in the refrigerator (2 to 8 °C); once opened, it may be stored for up to 4 weeks, but not above 30 °C [6]. Insulin above 30 degrees is therefore outside the manufacturer's stated range, and in a car or direct sunlight, it can quickly become that warm. A review of insulin storage identifies high temperatures and direct sunlight as factors that accelerate insulin degradation [2]. A Cochrane review of human insulin assessed how quickly this happens: In laboratory studies, there was generally no clinically relevant loss of efficacy over several weeks at temperatures of up to 37 °C, but two studies found up to 18 percent loss after one week to 28 days at 37 °C [1]. The review concerns human insulin only; the information for your insulin remains decisive.

Tip: Always keep your insulin cool, ideally in a cooler or with a special insulin cooling case (learn more in our insulin cooler guide). Make sure that blood glucose meters, sensors, and test strips are also not exposed to direct heat. Glucose sensors can also measure inaccurate values when the skin is overheated, and in hot weather, adhesive patches from sensors and insulin pumps, along with the device, can come loose from the skin [7]. You can find what you need to know about this in our summer sensor guide. The exact temperature limits for each insulin variant are listed in the package insert.

At Zuckerschmuck, you'll find bags for carrying insulin while traveling: from the diabetes travel bag and the cooling insulin pen cooler to the cooler for insulin ampoules. There are also dedicated insulin pump bags.

Have you already discovered our coolers from FRIO? They come in many colors and varieties, such as this one: FRIO Design Cooling Travel Case 2 Pens Tropical.

2. Fluid balance: drinking is especially important with diabetes

At high temperatures, the body loses fluid more quickly through sweating and also through breathing. When there is a lack of fluids, blood sugar levels can rise because the glucose in the blood becomes more “concentrated". At the same time, physical activity or exercise can cause hypoglycemia.

Tip: Drink enough. Water or unsweetened drinks are best. Ideally, drink 1.5 to 2 liters daily, and more in hot weather. Watch for signs of dehydration: headaches, dizziness, difficulty concentrating, or dry skin.

3. Exercise and sports: good for blood sugar, but not without planning

In summer, many people are more active, whether swimming, hiking, or cycling. This is generally good, but increased activity can lead to hypoglycemia, especially in combination with heat. The DDG practical recommendations on diabetes and exercise state that heat and cold affect the interaction of insulin, glucose, and stress hormones, and that more frequent blood sugar checks are indicated in these cases [3]. The DDG Diabetes, Environment and Climate working group recommends scheduling exercise in hot weather for the early morning or late evening whenever possible [7].

Tip:

• Measure your blood sugar regularly before, during, and after exercising.
• Always carry fast-acting carbohydrates with you (e.g. dextrose or fruit juice; find out more in our guide to dextrose for hypoglycemia). In hot weather, hypoglycemia can be tricky because sweating, thirst, and exhaustion can also be caused by the heat [7].
• Hypoglycemia can easily go unnoticed while swimming. Dry your hands carefully before measuring your glucose [7].
• Also be aware of the after-effects. Hypoglycemia can occur several hours after exercising [3].

We offer hypo boxes for your fast-acting carbohydrates on the go, such as the Diabetes HYPO BOX large “Dont eat my Hypo Treats". You can also find more tips specifically on sports and diabetes in our detailed main article on sports.

4. Traveling with diabetes: preparation is everything

Different time zones, changes in eating habits, or unfamiliar physical activities can affect blood sugar levels. The risk of forgetting important items or exposing them to heat is also higher when traveling.

Tip:

• Take enough medication, meters, and accessories with you. It is better to have a little too much than too little.
• Keep everything in your hand luggage, including when traveling by plane. Insulin does not belong in the cargo hold because it can get very cold there, and insulin can lose effectiveness at low temperatures [8].
• For emergencies: ideally, a medical certificate in English confirming that you are carrying insulin and syringes in your hand luggage. diabetesDE provides a form for download [4]. Also bring a diabetes emergency ID card, copies of your medical certificates, and, if applicable, an international diabetes passport.
• Airport security screening: Manufacturers provide different guidance. Abbott writes that you can pass through metal detectors with the Freestyle Libre system, but should not expose it to certain full-body scanners (X-ray and millimeter-wave scanners) [9]. For the G7, Dexcom allows metal detectors and body scanners with Advanced Imaging Technology and advises asking for a visual inspection at the baggage scanner [10]. Check with your device manufacturer before your flight.

To make sure you really have all the items related to your diabetes with you on vacation, we recommend one of our travel bags. The advantage is that you can store everything together and do not have to search for anything. Feel free to browse our Diabetes Travel Bag category.

5. Do not neglect foot care when you have diabetes

In summer, you walk barefoot or in open shoes more often. This increases the risk of injuries, sunburn, or burns. Especially with diabetic neuropathy (reduced pain sensation, a possible late complication of diabetes), minor injuries can quickly go unnoticed. The DDG working group therefore advises against walking barefoot in hot weather [7]. diabetesDE recommends checking your feet daily for injuries or pressure points, because nerve damage often prevents you from feeling warning signs such as shoes that are too tight or a small stone in your shoe [5]. The term for this is diabetic foot syndrome, often simply called “diabetic foot.”

Tip (according to diabetesDE [5] and the DDG working group [7]):

• Wear protective footwear, including at the beach or pool.
• Check your feet daily for injuries or pressure points.
• After washing, apply a moisturizing cream to your feet. This prevents skin cracks that can serve as entry points for pathogens.
• Trim your nails with a nail file whenever possible and remove calluses with a pumice stone or callus file.
• After swimming, dry the spaces between your toes particularly well. The skin there is especially susceptible to fungal infections.

You can find a care cream for legs and feet from us, for example, in the Diarin leg and foot cream.

Conclusion: Getting through summer safely with diabetes, with planning and mindfulness

Getting through summer with diabetes is manageable if you keep a few things in mind. Heat, fluid balance, physical activity and good preparation make all the difference. And even if summer brings one challenge or another: With a little planning, summer remains what it should be: sunshine, warmth and vacation.

Frequently asked questions about diabetes and heat

Is blood sugar higher in summer?

This can happen, but it does not have to. Whether blood sugar rises or falls in hot weather depends on several factors. High blood sugar in hot weather is possible if insulin has been stored too warm and loses effectiveness [2], or in cases of dehydration. Alcohol and caffeine can additionally lead to water loss and blood sugar fluctuations in hot weather [7]. At the same time, insulin can work significantly faster in warm skin, and physical activity can more easily lead to low blood sugar [7]. That is why the DDG working group recommends measuring more frequently in hot weather [7].

Does insulin work differently in hot weather?

Yes, this can happen. When insulin is injected into warmed skin, the skin has increased blood flow, and the insulin reaches the bloodstream more quickly. According to the DDG Diabetes, Environment and Climate working group, its effects may then begin significantly faster, and adjustments to the insulin dose are not uncommon [7]. Talk to your diabetes team about this.

Related topics

• Ice cream with diabetes: How many carbohydrates are in a scoop, soft serve and sorbet.
• Gifts for people with diabetes: What goes down well and what is better left on the shelf.
• Diabetes socks and why they matter: What non-binding socks can do for sensitive feet.
• Low-carb sweets for people with diabetes: Chocolate, gummy bears and cookies with few countable carbohydrates.

Sources

1. Richter B, Bongaerts B, Metzendorf M-I. Thermal stability and storage of human insulin. Cochrane Database of Systematic Reviews 2023, Issue 11. Art. No.: CD015385. DOI: 10.1002/14651858.CD015385.pub2. Available at: cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015385.pub2.
2. Heinemann L, Braune K, Carter A, Zayani A, Krämer LA. Insulin Storage: A Critical Reappraisal. Journal of Diabetes Science and Technology 2021;15(1):147–159. Available at: pmc.ncbi.nlm.nih.gov/articles/PMC7783014.
3. Esefeld K, Kress S, Behrens M, Zimmer P, Stumvoll M, Thurm U, Gehr B, Halle M, Brinkmann C. Diabetes, sport, and exercise. Diabetologie und Stoffwechsel 2023;18(Suppl 2):S314–S323. Practical recommendations of the German Diabetes Association. Available at: DDG Practical Recommendations for Sport 2023 (PDF).
4. diabetesDE, German Diabetes Aid. Medical certificate for air travel and border controls. Form for download. Available at: diabetesde.org/aerztliche-bescheinigung-fuer-flugreisen-und-grenzkontrollen.
5. diabetesDE, German Diabetes Aid. Give your feet special attention. Available at: diabetesde.org [Zugriff: 14.09.2026].
6. European Medicines Agency (EMA). NovoRapid: Summary of Product Characteristics, section 6.4 Special precautions for storage. Available at: ema.europa.eu (PDF) [accessed: 14.09.2026].
7. German Diabetes Association, Diabetes, Environment & Climate Working Group. Information on general conduct for people with diabetes in hot weather. As of 20.08.2024. Available at: ddg.info (PDF) [accessed: 14.09.2026].
8. diabinfo.de, the diabetes information portal. Traveling with diabetes. Available at: diabinfo.de [Zugriff: 14.09.2026].
9. Abbott. FreeStyle Libre: Frequently asked questions about traveling. Available at: freestylelibre.de [Zugriff: 14.09.2026].
10. Dexcom. Can I wear the Dexcom G7 during airport security screening or while flying? Available at: dexcom.com [Zugriff: 14.09.2026].

Note: This article is a collection of practical tips and does not replace medical or nutritional advice. For detailed questions about insulin storage (e.g., specific manufacturer specifications for individual insulin variants), contact your pharmacy or the manufacturer. For questions about therapy adjustments related to heat, exercise, or changes in time zones, contact your diabetes care team.