Swimming and Type 1 Diabetes: Preparing Is Key to Enjoy the Water!

With summer just around the corner, there will be countless opportunities to go for a swim in pools, lakes, rivers, the sea, and even water parks.

But if you or your child have type 1 diabetes (T1D), this fun activity can raise questions, or even cause anxiety, which is why preparation is key.

What impact can swimming have on blood sugar? Will the sensor of your continuous glucose monitor (CGM) fall off? Can you even go swimming with an insulin pump?

If you’re asking yourself those questions, you’re in the right place.

Here’s what you need to know about swimming and T1D.

Blood sugar management

The impact of your swim on your blood sugar levels will depend on the water activity in question.

You (or your child) could use this time in the water to:

Do swimming laps. In that case, blood sugar levels could decrease, just like with any other low- to moderate-intensity exercise. When swimming in the sea, the waves can increase the intensity of the swim as well as your risk of low blood sugar. Conversely, your blood sugar could increase if you do activities such as interval-based swimming laps or water polo.

Relax or go for a leisurely swim. In that case, the risk that your swim will impact your blood sugar is low.

However, the heat can also play a role and lower blood sugar levels. So, you need to be extra cautious in very high temperatures.

If it’s your first swim with T1D, the stress of the new environment (water, waves) can sometimes increase blood sugar levels.

To properly assess the impact of swimming on blood sugar, the best solution remains to regularly check your levels before, during and after the activity. Planning the activity can also help you to implement strategies to limit its impact on blood sugar and avoid hypoglycemia. You can find several examples of strategies you can use in this article (in French only).

You can find the best strategy to limit the impact on your blood sugar through trial and error. Keeping a physical activity log where you write as much information as possible (e.g., blood sugar measurements, insulin doses, type of activity based on time of day) can be a good way to assess the strategies that you test out.

Continuous glucose monitors

If you or your child use a CGM (e.g., Dexcom, FreeStyle Libre), the sensor applied to the skin (and its transmitter, if applicable) can go in the water and stay in place during your swim. However, it’s possible for the device to fall off. To avoid this kind of problem, you can secure the sensor by using certain adhesive products under or over it (e.g., products listed here, Not Just a Patch dressings). Note that applying a dressing over the Dexcom transmitter is not recommended because this could lead to a loss of signal.

In the case of monitors that automatically transmit data (e.g., Dexcom, Guardian) and/or provide alerts (e.g., FreeStyle Libre 2), the water itself or the distance from the receiver can hinder data transmission. This loss of communication can prevent your CGM from displaying your blood sugar levels and triggering alerts.

See this table for more information on CGMs.

Insulin pumps

If you or your child use an insulin pump, the watertightness of the device varies according to the manufacturer. See this table with information from manufacturing companies, including watertightness, if applicable.

Pump with tubing (e.g., Medtronic, Tandem). Even when manufacturers say their pumps are waterproof, this very much depends on the condition of the pump (e.g., age, seal watertightness). In general, these companies will easily and quickly replace a pump in the event of problems, but having a non-working pump can be an extremely stressful situation. That’s why these pumps are considered more to be water-resistant (e.g., accidental fall in the water, drop of water on the pump). However, there are two strategies you can use to enjoy some water fun and preserve your peace of mind.

1. 1. Disconnecting the pump. This is the most recommended strategy. The catheter stays in place, but you remove the tubing and the pump (in theory, a cap needs to be placed at the end of the removed tubing for hygiene reasons). It is suggested not to disconnect the pump for more than two hours and to regularly check blood sugar (before/during/after). And don’t forget to reconnect the pump once your swim is over!
  2. Using a waterproof case. There are specially designed cases that can go in the water and keep their contents dry (e.g., Aquapac). These cases can also help to avoid sand coming into contact with the pump.

Pump without tubing. The pod (an insulin-containing wireless device that is applied to the skin) that is used with the Omnipod pump is waterproof. However, you need to make sure that the pod is securely in place. There are products that help the device stick to the skin. There are also dressings that can be applied over the pod (e.g., products listed here, Not Just a Patch dressings).

Since the pod contains insulin, you need to be cautious when swimming in very warm or very cold waters (e.g., spas), which could impact insulin efficacy. Don’t forget to change pods if you have any doubts.

Emergency kit

One thing cannot be overstressed: preparing is key for being able to face any possible situation.

In addition to carrying your blood sugar meter (capillary meter or CGM) and your insulin pens or pump, don’t forget to:

Bring some sugar (in case of hypoglycemia) and snacks.
Keep your insulin in a cool shaded place (especially in high heat). There are cases that can keep your insulin cool (e.g., FRIO, Glucology). If you’re unsure about its efficacy, change the insulin inside your pen or pump.
Bring the necessary supplies to change your CGM’s sensor and/or your pump’s catheter (or pod) in case it falls out.
Stay hydrated. The heat can lead to dehydration and can increase blood sugar. So, it’s important to drink plenty of water to prevent the risk of diabetic ketoacidosis.
Bring some sunscreen. This basic tip is important for avoiding sunburns, which can lead to blood sugar spikes due to the stress on the body.