Swimming is terrifically healthy and boasts many benefits for people with diabetes.
But diabetes does make swimming a little bit more complicated, especially if you use insulin. Swimmers with diabetes need to be mindful of the risk of hypoglycemia, and need to know how exactly to care for all of the electronic devices they use to manage their condition. This article has the details.
Swimming is Fantastic Exercise
There’s no doubt about it: Swimming is a superb exercise option for people with (or without) diabetes. The health benefits of swimming are almost too numerous to list. As Everyday Health details, swimming is associated with, among other things:
Improved mood and better sleep
In addition, swimming is associated with several health effects of special relevance to people with diabetes:
A 2021 study found that regular swimming resulted in comprehensive metabolic improvements, including better blood pressure, cholesterol, blood glucose, and body fat.
A 2019 study found that a swimming intervention alleviated insulin resistance and improved chronic inflammation.
A 2020 study found that swimming can improve blood sugar control.
Swimming is incredibly good for your body and is recommended for people of every age, fitness level, and shape.
Swimming and Diabetes Complications
Swimming is an especially good option for people with chronic pain, mobility challenges, or diabetic neuropathy, due to its low-impact nature.
The buoyancy of the water relieves pressure on the feet and may reduce the risk of injury to the lower extremities. Additionally, the water’s resistance provides gentle resistance training, which can help strengthen muscles, improve balance, and enhance overall coordination, addressing some of the challenges associated with diabetes. And aquatic aerobics can be great for many of the same reasons. Put it all together: Swimming is a great way to enjoy the benefits of exercise while minimizing the risk of injury.
Safe Swimming and Hypoglycemia
Swimming presents one unique hazard to people with diabetes — the threat of hypoglycemia. Everyone with diabetes that takes insulin or sulfonylureas is considered at risk. If you experience severe low blood sugar in the water, it could create a drowning hazard. And the act of swimming, both the fatigue of exercise and the unusual aquatic environment, can help mask the symptoms of hypoglycemia. As such, swimmers will need to take special precautions:
First, pay extra attention to your blood sugar levels, both before and during swimming. That may mean taking multiple extended breaks to get out of the pool and use a glucose meter, or to dry off your hands to check your continuous glucose monitor readings on your smartphone.
If you know that you tend to go low during exercise, consider starting your swim with your blood sugar a little higher than usual, or plan to consume some carbohydrates midway through your swimming session. If you use an insulin pump, you could reduce your basal rates 30-90 minutes before starting. If your insulin pump is waterproof and can stay attached during your exercise, you may want to set a temporary lower basal rate or use “exercise mode.”
You should always have a source of fast-acting carbohydrates accessible, ideally right at the pool’s edge.
Consider letting the lifeguard know that you have diabetes so that they can keep an eye on you. A medical alert bracelet is another wise choice. If disaster strikes and you experience a hypo that you cannot treat yourself, you’ll get the care you need far more quickly if paramedics know that you have diabetes.
Like other forms of exercise, you can ensure steadier blood sugar levels by swimming in the morning (before you’ve eaten breakfast and taken rapid insulin).
Finally, you’ll need to be clear about the capabilities of your electronic diabetes devices.
Swimming and Continuous Glucose Monitors
The leading continuous glucose monitors (CGMs) are water-resistant:
The FreeStyle Libre can be submerged up to 3 feet deep for up to 30 minutes.
Dexcom can be submerged up to 8 feet deep for up to 24 hours.
Medtronic’s Guardian Connect can be submerged up to 8 feet deep for up to 30 minutes.
Many users swim with their CGMs without the slightest problem. Others worry that their CGM is even less water-resistant than advertised — the resistance ratings are for still water, not for splashy water — and decide to cover their sensors. There’s an array of armbands, patches, and tapes available on the internet that are intended to protect a CGM sensor from water.
However, your CGM may not work very well during a swim. Water impedes the Bluetooth signal that your CGM uses to communicate with a receiver or a smartphone, significantly shortening its range. If you’re at the opposite end of the pool as your device, you can’t expect new blood sugar measurements to get through. Even if you stay within a few yards, the water could block the signal.
In short, you might not get new CGM readings until you leave the pool, which means that you cannot rely on your device’s low blood sugar alarm function while swimming.
Swimming and Insulin Pumps
Insulin pumps vary in their water resistance ratings. Here are some of the more popular options available in America:
The Omnipod 5 is rated as waterproof for depths up to 25 feet for up to 60 minutes.
The Tandem t:slim X2 is rated as water-resistant for depths of up to 3 feet deep for up to 30 minutes, however, the manual advises that the pump should not be worn while swimming, or even in a hot tub.
The Medtronic MiniMed 780G system is rated as waterproof at depths of up to 12 feet for up to 24 hours.
The new iLet Bionic Pancreas is rated as waterproof at depths of up to 12 feet for up to 30 minutes.
Be sure to check the manufacturer’s instructions for your specific model.
If you’re required to disconnect your insulin pump before getting into the water, you should be prepared with an understanding of the risks involved with completely stopping insulin delivery. This technique is commonly used by athletes with type 1 diabetes, but it always carries a risk of rising blood sugars and even diabetic ketoacidosis. If you have a very long swimming session planned, our community manager Julie De Vos recommends reconnecting to your pump every hour and delivering a bolus.
Please discuss your options with your healthcare provider.
Open Water Swimming
Swimming in open water — the open ocean, large lakes, or anywhere else that you’re far away from a place to rest — requires extreme caution. Developing hypoglycemia (or ketoacidosis) far from shore could quickly become a life-threatening situation.
With the right preparation, just about anything is possible. Paul Spurway, a long-distance outdoor swimmer with diabetes, helped author a detailed guide to swimming safely in open water, offering ideas on carbohydrate intake, insulin usage, and electronic diabetes devices. He spoke to our friends at diaTribe about his experience.
When he’s racing, Paul is accompanied by support boats that can help monitor his blood sugar and distribute sugar when necessary. Most of us don’t have that opportunity when we’re swimming casually at the beach. Going out far from shore, without sugar or the ability to monitor glucose, can be very dangerous.