Quick answer: Many adults with type 2 diabetes swim or do water exercise, and a small body of research suggests it can lower HbA1c about as much as land exercise does. The same exercise guidelines apply in the water: about 150 minutes a week of moderate or harder activity, spread over at least three days. The main extra issues are low blood sugar if you take certain medicines, foot and skin checks, never swimming alone, and checking what your sensor or pump maker says about water. This is general education, not a personal exercise prescription.
Swimming rarely gets as much attention as walking or running, yet it comes up often when people with type 2 diabetes have sore knees, stiff hips, extra body weight, or a doctor who said, “find something easy on your joints.” This guide covers what the research actually shows, how swimming fits the exercise guidelines, how to protect your blood sugar and feet, what the makers of common sensors say about water, and how to build a sensible first month. It sits next to our guides on walking after meals, running, and strength training, and a companion guide on high-intensity interval training.
A note on where this comes from: Charles Kirkland is not a physician or a swim coach, and nothing here is a personal swimming result. After his own diagnosis, exercise changed from something he meant to get to into something he pays real attention to, and the realization that he does not have enough muscle mass is a big part of why. This guide is a summary of published sources, written so you can ask better questions of your own care team.
Why swimming deserves a look
Three reasons come up repeatedly in the sources we checked. First, water supports body weight, so swimming and water aerobics are low-impact. A set of exercise-prescription slides presented by Ronald Sigal in 2017, which summarize the 2016 American Diabetes Association position statement, suggest considering water-based exercise “if weight-bearing or arthritis limits physical activity.” Second, the same slides list swimming laps as an example of vigorous-intensity exercise and water aerobics as an example of moderate-intensity exercise, so the water can cover a wide range of effort. Third, a diabetes education site (diaTribe) notes that water aerobics can be made harder by adding repetitions, speed, or water-resistance equipment, which means the same pool can work for a beginner and for someone who is already fit.
There are real downsides too. Pools cost money or require a membership, travel takes time, and one of the news summaries of the aquatic research points out that access to a pool because of cost, availability, or distance can make water exercise hard to keep up. If a pool is not realistic for you, walking and strength training remain very reasonable options.
What the research shows
The most useful single source we found is a 2017 meta-analysis by Jordan Rees, Steven Johnson, and Normand Boulé in Acta Diabetologica (volume 54, pages 895 to 904). It pooled nine trials with 222 participants who did aquatic exercise for at least eight weeks. The exercise in the trials included walking or running in water, cycling, and water-based fitness classes, according to a news summary of the paper. The numbers below come from the Athabasca University record of the paper and the HCPLive news summary, not from the full text, which we could not open.
| Comparison | Change in HbA1c | What it means |
|---|---|---|
| Water exercise vs land exercise | -0.02 percentage points (95% CI -0.71 to 0.66) | No detectable difference between the two in these trials |
| Water exercise vs no-exercise comparison | -0.96 percentage points (95% CI -1.87 to -0.05) | Lower HbA1c with water exercise, with a very wide range |
| After water exercise vs before | -0.48 percentage points (95% CI -0.66 to -0.30) | A before-and-after drop with no comparison group |
Source: Rees, Johnson and Boulé, Acta Diabetologica 2017, as reported in the Athabasca University record and an HCPLive summary. Percentage points are absolute changes in HbA1c.
Several cautions belong right next to those numbers. The trials were small and short. A confidence interval that runs from -1.87 to -0.05 means the true effect could be anywhere from large to barely there. The HCPLive summary quotes the authors as saying many of the studies were small and short-term and that more research is needed to compare land and water exercise over longer periods. The two summaries also disagree on one detail: the Athabasca record says three trials compared water with land exercise, while the news summary says two did, so we describe the land-versus-water comparison without citing a trial count. The summaries report blood pressure, cholesterol, and triglyceride improvements in some participants after eight to twelve weeks, but they give no numbers for fasting glucose or weight, so we do not either.
The takeaway is modest and honest: in small trials, water exercise looked about as helpful for HbA1c as land exercise. It is not proof that swimming is better than walking, and it does not tell you what will happen to your own glucose. If you wear a CGM, reading your own data is the better test.
How much swimming counts toward the guidelines
The widely cited joint guidance from the American College of Sports Medicine and the American Diabetes Association, as summarized in the sources we could open, recommends at least 150 minutes a week of exercise at a moderate or greater intensity, spread over at least three days with no more than two days in a row without activity. It also recommends resistance exercise at least twice a week on non-consecutive days. A 2024 handbook from the Royal Australian College of General Practitioners (RACGP) repeats the 150-minute target and adds that prolonged sitting should be interrupted about every 30 minutes, a recommendation it grades as lower certainty than the exercise targets. Swimming alone does not cover strength work, so most plans pair it with strength training.
| Water activity | Typical intensity category | Notes |
|---|---|---|
| Water aerobics or a class | Moderate (example given in the Sigal slides) | Easier on joints; can be made harder with speed or resistance gear |
| Swimming laps | Vigorous (example given in the Sigal slides) | Pace and skill matter; a beginner may not reach this level for long |
| Water walking | Depends on speed and depth | A reasonable starting point for people returning to exercise |
| Open-water swimming | Varies | Extra safety issues; see the open-water section |
Intensity categories are a guide, not a promise. Your own effort level, fitness, and technique decide what a pool session feels like. A simple talk test works in the pool as it does on land: moderate effort usually means you can talk in short sentences but not sing.
The Sigal slides also say that people with low fitness, arthritis, or obesity can begin with very small amounts of activity, for example five minutes a day, and increase gradually. That advice fits swimming well: three short sessions a week of easy water walking is a legitimate beginning.
Low blood sugar and swimming: who needs to think about it
Low blood sugar during or after exercise is mainly a concern for people who take insulin or medicines that raise insulin levels, such as sulfonylureas. A 2010 summary of American Diabetes Association standards says hypoglycemia is rare in patients who are not treated with these drugs, and that people on insulin or insulin secretagogues should take additional carbohydrate if the pre-exercise glucose level is below 100 mg/dL. That summary is more than fifteen years old, so treat the number as an example of how guidance is framed, not as your personal target. The RACGP handbook says that if you use insulin or sulfonylureas, you should check your blood glucose before exercise and every 30 to 45 minutes during it, that delayed low blood sugar can occur up to 48 hours after exercise, and that you should carry a rapid-acting glucose source.
Diabetes UK adds swimming-specific points. Its swimming page says insulin sensitivity can stay higher for up to 48 hours after swimming, that swimming can also raise blood sugar in some people, and that if you take insulin or sulphonylureas you should talk to your healthcare team before swimming because your dose may need changing. We do not give any medicine-adjustment advice here. If you take these medicines, the dose and timing plan belongs to your prescriber.
Why does this matter more in the water? Because a low in a pool is not like a low on a sofa. Confusion and weakness in water can be dangerous. That is the reason nearly every source we checked says not to swim alone, to tell the lifeguard you have diabetes, and to consider wearing a medical ID. The diaTribe article recommends keeping a glucose meter, test strips, and snacks in a waterproof container, and a swim buddy or a group class is its preferred setup.
A pre-swim checklist
The Mayo Clinic article “Diabetes and exercise: When to monitor your blood sugar” (dated January 9, 2024) gives a framework many people use for exercise in general. It says to test 15 to 30 minutes before exercising if you take insulin or other medicines that can cause low blood sugar, to check every 30 minutes during long workouts, to check as soon as you finish, and then again over the next few hours. The thresholds below are from that page. They are written for people at risk of low blood sugar, so ask your care team which numbers apply to you.
| Pre-exercise glucose (mg/dL) | What Mayo says |
|---|---|
| Under 90 | May be too low to exercise safely; eat 15 to 30 g of carbohydrate or take 10 to 20 g of glucose |
| 90 to 124 | Take about 10 g of glucose before you exercise |
| 126 to 180 | Ready to exercise; glucose can rise with strength work or hard intervals |
| 182 to 270 | OK to exercise, with the same caution |
| Over 270 | Caution zone; check ketones first if that applies to you |
Mayo also says to stop exercising if your glucose is 70 mg/dL or lower or if you feel shaky, weak, dizzy, or confused, and not to exercise if you have needed help recovering from a serious low in the past 24 hours. It lists options for treating a low during exercise, including glucose tablets or gel, half a cup of juice, half a cup of regular soda, hard candy, or a tablespoon of sugar or honey, about 15 grams each time with a recheck after 15 minutes. Pool decks are not the place to figure this out for the first time. Plan where your fast carbs will be, and make sure they are within reach.
Eating around a swim
Diabetes UK offers practical timing advice that many people find useful, with the caveat that it is general guidance and not a personal plan. It suggests leaving at least three to four hours after your last meal before swimming, and says a snack such as a cereal bar, fruit, or yogurt can be eaten one to two hours before if needed. For swims under an hour you usually do not need food, though a snack can help if you are at risk of lows. For longer, harder swims, over an hour, glucose sports drinks or gels can provide carbohydrate, though they will affect blood sugar, and getting out for a snack is often easier than eating in the pool. It also recommends eating carbohydrate and protein soon after swimming, and drinking water before, during, and after, because you do sweat in the water.
If you are not on a medicine that causes low blood sugar, you may not need any special pre-swim snack. If you are trying to lose weight, a snack may be unnecessary. Both choices are worth asking your care team about rather than guessing. For general food questions, see our diabetes food guide and the comparison of eating patterns.
Feet, skin, and the locker room
Pools bring wet floors, shared showers, and long stretches of soaked skin. The diaTribe article suggests lightweight water shoes in the pool and shower sandals in the locker room to reduce the risk of bruises, cuts, and athlete’s foot, and says to examine your feet after you leave the pool for cuts, bruises, or abrasions. Diabetes UK says to wear flip-flops in the shower and around the pool, to check your feet each time you swim for changes in color or sensation and for blisters, cuts, or ulcers, and to contact your healthcare team if a sore is not healing.
The 2010 ADA summary says moderate-intensity walking does not appear to increase foot ulcer risk, that people should wear proper footwear and examine their feet before and after each session, and that anyone with a foot injury or ulcer should avoid weight-bearing activity. Swimming is not weight-bearing in the same way, but a wound is still a wound: ask your clinician before swimming with an open sore, a blister, or a new cut, and if you have numbness in your feet, make the post-swim foot check a habit you never skip.
Eyes, heart, and other cautions
Some diabetes complications change which exercise is appropriate. The RACGP handbook says vigorous exercise is contraindicated for people with proliferative retinopathy, that exercise may be relatively contraindicated with peripheral neuropathy, recurrent falls, or uncontrolled hypertension, and that anyone who develops cardiovascular symptoms should moderate or stop activity and have the symptoms investigated. The 2010 ADA summary lists unstable proliferative retinopathy, severe neuropathy, and uncontrolled hypertension as examples of complications that might preclude certain activities, and says the pre-exercise evaluation should focus on identifying those complications rather than routine heart screening of people with no symptoms. Diabetes UK says you can swim with eye problems but to ask your healthcare team whether diving is safe for you.
Hard swimming sets, sprints, and holding your breath can all raise blood pressure and effort quickly. If you have retinopathy, high blood pressure, heart disease, or neuropathy, get clearance and guidance before you add vigorous swimming. Easy water walking and gentle water aerobics are different conversations than lap sprints.
Sensors, pumps, and water
Many people ask whether a continuous glucose monitor can go in the pool. The honest answer is that it depends on the product and its current instructions, and the instructions change. The table below summarizes what the makers’ own pages said when we checked on October 31, 2026. Always read the current instructions that came with your device.
| Sensor | Water statement on maker page | Practical note on that page |
|---|---|---|
| Stelo (Dexcom) | Can be wet while bathing, showering, or swimming; waterproof up to 8 feet (2.4 m) for up to 24 hours if properly installed | Phone may need to be within 20 feet; readings may stop in water; patch stays on longer if kept dry |
| Dexcom G7 | Described as waterproof for up to 24 hours at a depth up to 2.4 m on Dexcom’s UK page | Keep phone or receiver close; readings may drop out in water and the sensor sends stored data after you are back in range |
| FreeStyle Libre 3 Plus | Water-resistant in up to 1 meter (3 feet) of water; do not immerse longer than 30 minutes | Bluetooth performance may be affected underwater |
Sources: stelo.com FAQ, Dexcom UK FAQ page on getting the sensor wet, Abbott FreeStyle Libre 3 Plus water-resistance FAQ. We did not verify other sensors. The Dexcom page we read did not mention Stelo; the Stelo FAQ is its own page. Neither page stated an IP rating.
Three practical takeaways. First, Bluetooth does not travel well through water, so a phone left on the deck may lose the sensor while you swim; Dexcom’s page says the sensor keeps collecting data and sends it when you are back in range, but you may miss alerts in the meantime. That matters if you rely on alarms for lows. Second, the adhesive is usually the weak point, not the sensor. The Stelo page says the patch stays on longer if kept dry, and the Dexcom page says to pat the patch dry after swimming and to rinse after sea or river water. See our guide to CGM adhesive and overpatch tips if edges lift. Third, saunas and steam rooms are a separate matter: the Dexcom page says they may exceed 42 degrees Celsius and 90 percent humidity and that regular heat exposure may weaken the adhesive.
If you use an insulin pump, both diaTribe and Diabetes UK say to ask your healthcare team whether it is safe to disconnect it while swimming and to check with the manufacturer about water and chlorine resistance. We do not give pump advice here. For using a CGM during exercise in general, see exercising with a CGM, and for the broader picture, how to read your CGM data.
Open water, cold water, and heat
Diabetes UK suggests open-water swimmers use supervised venues or clubs rather than wild swimming, never swim where signs advise against it, avoid stagnant water, weirs, and locks, and check their feet before and after entering the water or wear aqua shoes. It adds that cold water raises glucose use and can trigger stress hormones that raise blood sugar, that endorphins can mask the symptoms of a low, so extra care is needed if you take medicine that can cause lows, and that wetsuits can help with cold and protect diabetes equipment. It also recommends acclimatizing gradually with short first sessions.
Pools can be warm and humid, hot tubs hotter still. The sources we read give no tub-specific guidance, and the Libre 3 Plus page does not address hot tubs or saunas. Ask the manufacturer or your clinician before wearing a sensor in one.
A first month, with the arithmetic
The plans below are examples built so you can see how minutes add up against the 150-minute target. They are not prescriptions. Each session is counted at its full length, including easy portions.
| Stage | Example week | Weekly minutes |
|---|---|---|
| Starter | 3 sessions of 20 minutes of water walking or easy water aerobics | 60 |
| Building | 2 sessions of 30 minutes of water aerobics plus 1 session of 20 minutes of easy laps | 80 |
| Target | 3 sessions of 30 minutes of steady swimming plus 2 sessions of 30 minutes of water aerobics | 150 |
| Target plus strength | The target week plus 2 strength sessions of 30 minutes | 210 total, of which 150 is aerobic |
Notice that the Starter week is 60 minutes, which is 40 percent of the 150-minute target. That is fine as a place to start. The Sigal slides say to begin small and build gradually. Each stage could last a few weeks, not a few days, and the right pace depends on your fitness, joints, and medicines.
Which scenario sounds like you
Prediabetes
If you have prediabetes, swimming is one more way to reach the weekly activity target, especially if joints or weight make running unappealing. Nothing in the sources we checked says swimming is better than other activity for prediabetes, so choose what you will actually keep doing.
Type 2 diabetes, no glucose-lowering medicine that causes lows
For people not on insulin or sulfonylureas, the 2010 ADA summary says low blood sugar from exercise is rare. The foot, skin, safety, and eye and heart points still apply. Check with your clinician before starting if you have any complication.
Type 2 diabetes on insulin or a sulfonylurea
This is the clinician-first group. Ask about your plan for lows before you swim: what to check, when, what to eat, and what to do afterward, including up to a day or two later. Never swim alone, tell the lifeguard, and wear ID. Do not adjust any dose on the basis of this article.
CGM users
A CGM can show a trend before, during, and after a swim, but water can interrupt the signal, and the sensor can misread when pressed or heated. Treat what you see as information to bring to your clinician, not as a rule. Our post-meal glucose tracker is a simple way to log what happens around a swim.
Common mistakes
- Swimming alone, or without telling anyone you have diabetes.
- Leaving fast carbs in the car or locker instead of within reach.
- Skipping the post-swim foot check, especially with numbness.
- Assuming the sensor will stay connected without the phone nearby.
- Going hard in the first session because the water feels easy.
- Treating a low with a snack bar that is slow to absorb, when fast carbohydrate is needed first.
- Ignoring a sore, blister, or cut because pool water feels clean.
- Counting only swimming and forgetting strength work.
Myth versus fact
| Common belief | What the sources support |
|---|---|
| Swimming does not count as real exercise. | Laps and water aerobics are listed as vigorous and moderate examples in the Sigal slides. |
| Swimming beats every other exercise for blood sugar. | The meta-analysis found no difference from land exercise in HbA1c in a few small trials. |
| Water exercise cannot cause low blood sugar. | Sources describe low blood sugar risk with insulin or sulfonylureas, with delayed effects. |
| All sensors are fully waterproof. | Makers state different depths and time limits, and their pages change. |
| Chlorine disinfects any cut, so feet are safe. | Sources still tell people to check feet after every swim and wear water shoes. |
Questions for your clinician or dietitian
- Which of my medicines can cause low blood sugar with exercise, and what is my plan if I swim?
- What glucose numbers should I use before, during, and after a swim?
- Do I have any eye, nerve, kidney, or heart condition that limits how hard I should swim?
- Is it safe for me to swim with my sensor or pump, and what do I do if the signal drops?
- How should I check and care for my feet around pool use?
Frequently asked questions
Is swimming good for type 2 diabetes?
A 2017 meta-analysis of nine small trials found HbA1c fell after at least eight weeks of aquatic exercise and was not different from land exercise. The trials were small and short, so the evidence is modest.
How often should I swim?
Guidelines call for at least 150 minutes a week of moderate or harder activity over at least three days. Starting with 20-minute sessions and building up is a common approach. Ask your clinician what is right for you.
Can swimming cause low blood sugar?
It can in people who take insulin or sulfonylureas. Sources describe delays of hours up to one or two days after exercise. Talk with your care team about your plan, and never swim alone.
Should I eat before swimming?
Diabetes UK suggests leaving three to four hours after a meal and a light snack one to two hours before if needed. Whether you need one depends on your medicines, so ask your clinician.
Can I wear my CGM in the pool?
Stelo and Dexcom say their sensors can get wet; Abbott says Libre 3 Plus is water-resistant to 1 meter for up to 30 minutes. Check the current instructions for your device, and expect signals to drop out underwater.
What about my insulin pump?
Sources say to ask your healthcare team whether disconnecting is safe and to check the manufacturer about water and chlorine resistance. We do not give pump advice.
Is water aerobics enough?
Water aerobics is listed as a moderate-intensity example, so enough sessions can count toward the 150-minute target. Adding strength work two or more days a week is also recommended.
Is swimming safe with neuropathy?
Sources advise foot checks after every session and water shoes, and say neuropathy may limit some exercise. Ask your clinician before starting if you have numbness or foot problems.
Can I swim with eye problems?
Diabetes UK says yes in many cases but to check whether diving is safe. Vigorous exercise is contraindicated with proliferative retinopathy according to an Australian handbook, so ask your eye doctor first.
Is open-water swimming okay?
Diabetes UK recommends supervised venues, checking your feet, and extra care because cold water and endorphins can affect glucose and mask lows. Start with short sessions and a buddy.
Sources checked
- Rees, Johnson and Boulé, Aquatic exercise for adults with type 2 diabetes: a meta-analysis, Acta Diabetologica 2017 (Athabasca University record)
- HCPLive, Aquatic exercise equals land exercise for blood sugar levels in T2D patients (2017)
- Mayo Clinic, Diabetes and exercise: When to monitor your blood sugar (Jan 9, 2024)
- Diabetes UK, Swimming when you have diabetes (undated page)
- diaTribe, Swimming and water aerobics (undated page)
- Sigal, How to Prescribe Exercise for Almost Anyone, slides presented Feb 18, 2017 (summarizing the 2016 ADA position statement)
- RACGP, Management of type 2 diabetes handbook: Physical activity (recommended as of Nov 14, 2024)
- Patient Care Online, Diabetes: Exercise Guidelines (Nov 10, 2010; summarizes ADA 2010 standards)
- Stelo, Can I get my Stelo Glucose Biosensor wet?
- Dexcom UK, Can I get my Dexcom sensor wet?
- Abbott, FreeStyle Libre 3 Plus sensor water resistance details
Limits of this guide: PubMed and PubMed Central were not reachable, so studies are described from summaries. Several guideline sources are old or undated, and sensor water ratings change with each product update. The exercise guideline figures we cite come from secondary summaries, not the original ADA documents.
About the author: Charles Kirkland is the founder of Metabolic Clarity Labs and author of The Journey Back. He is not a physician. This is general education, not a medically reviewed treatment plan.
Sources checked October 31, 2026. Discuss personal decisions with a qualified clinician. Do not start, stop, or change prescribed treatment based on this article.
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