Scuba Diving and T1D 

Glucose Levels:

• • Your glucose levels should generally be between 126–216 mg/dL (7–12 mmol/L) before you dive. If your glucose levels are out of this range, you may need to wait to dive until your glucose levels are back in range or not changing much.
  • Using a CGM can help you know and manage your glucose levels before and after diving. You won’t get glucose readings while diving, but you can usually see CGM readings within 5-10 minutes after coming out from the water. Check your glucose levels with a fingerstick glucose meter and compare it to your CGM readings before and after each dive. If you don’t use a CGM, keep a glucose meter and test strips nearby to check your glucose levels frequently.

Insulin Strategies:

• • Consider lowering your long-acting (basal) insulin dose by 10-20% the night before diving (if you typically take your long-acting insulin in the evening) to reduce the risk of low glucose levels while diving.

Carbs/Meals/Snacks:

• • If eating a meal before diving, try to have it more than 3 hours before diving, to lower insulin levels in your body. Eating earlier helps lower the risk of quick drops in glucose levels during the dive. You should also make sure to stay hydrated on the day of your dive.
  • Consider lowering mealtime (bolus) insulin, by around 25-75% if you plan on diving 1-2 hours after eating.
  • May need to eat more carbs (around 30 grams) before diving, without adding extra insulin for the carbs, to prevent low glucose levels.
  • Visit our Tips for Preventing and Treating Low Blood Glucose Levels During Exercise for more recommendations.

Plan Your Dive and Communicate with Your Buddy:

• • As a person with diabetes, you should always dive with a buddy who knows that you have diabetes. The buddy should not have diabetes. Make sure your buddy knows where your devices (especially your CGM reader/phone, injections, and glucose meter) and fast-acting carbs are after the dive.

Before a dive, agree on a special hand signal with your dive instructor or dive buddy if you start to feel low during the dive. You might make an “L” with your hand or tap your arm where your CGM sensor is. Like other dive pre-checks, plan to go over this before every dive. This signal should be different from other safety signals used while diving.

^{Jendle JH, Adolfsson P, Pollock NW. Recreational diving in persons with type 1 and type 2 diabetes: Advancing capabilities and recommendations.}

Glucose Levels During the Dive:

• • You will not be able to see your glucose levels during your dive, even if you wear a CGM because water blocks the Bluetooth connection.
  • Be aware that your usual signs of low blood glucose may not be the same while you are underwater. Diving is a physical activity and can be difficult, even if you are fit. Pay attention to how your body is feeling, and if you notice a fast change in body temperature, feel tired, or lose your coordination, these could be underwater signs that your glucose could be heading low.
  • Some people carry glucose supplies (such as glucose tablets, gels, fruit snacks) with them while diving. If it is safe, you can come up to the surface, take your carbs, then continue your dive.

Dive Time:

• • Most diving tips suggest not diving for more than 1 hour^[2].
  • As a new diver, you should plan to stick to this, because it helps you lessen your risk of lows. The longer you dive, the more activity it is, and the more likely you are to have lows.
  • As you get more experienced, you can plan for longer dives if you have stable glucose levels and do not tend to have lows during your 1-hour dives.

You may need more carbs before longer dives. You should still plan ahead and be ready to stop any dive where you feel low glucose, even if you planned for it to be a longer dive.

Glucose Levels:

• • Check your glucose levels as soon as you come out of the water and get your gear off.
  • If you are low or feel low, you should treat with carbs.

Insulin Strategies:

• • After your dive, you can resume your usual insulin management strategies.
  • Like any physical activity, pay attention to your glucose levels for the next 12-24 hours after you dive.

Log Dive Details:

• • It is a good idea to log your dive, your glucose data, insulin dosing changes, and any fast-acting carbs that you needed the day of the dive. This will help you track trends and make any needed changes or decisions for future dives. This should include the timing of any meals around the time of the dive so you can compare the actions you took before the dive (not just minutes before) that may have impacted your glucose levels during the dive.
  • For example, if you are not going low during dives and find yourself with higher glucose levels post-dive, you may be able to adjust your pre-dive carb intake (such as 20 grams to 15 grams) for the next dive.

Glucose Levels:

• • Your glucose levels should generally be between 126–216 mg/dL (7–12 mmol/L) before you dive. If your glucose levels are out of this range, you may need to wait to dive until your glucose levels are back in range or not changing much.
  • Using a CGM can help you know and manage your glucose levels before and after diving. You won’t get glucose readings while diving, but you can usually see CGM readings within 5-10 minutes after coming out from the water. Check your blood glucose with a fingerstick glucose meter and compare it to your CGM readings before and after each dive. If you don’t use a CGM, keep a glucose meter and test strips nearby to check your blood glucose levels frequently.

Insulin Strategies:

• • Consider lowering your basal insulin rate by 50-80% around 1-2 hours before diving.
  • The goal is to try and start dives with low insulin on board (IOB) to reduce the risk of low glucose levels during dives.
  • Suspend and disconnect your insulin pump, including Pods (Omnipod), before diving. Reconnect your pump as soon as you can after diving to start insulin delivery and monitor glucose levels closely. These devices are not tested for deep water.

Carbs/Meals/Snacks:

• • If you eat a meal before diving, try to have it more than 3 hours before diving, to lower insulin levels in your body. Eating earlier helps lower the risk of quick drops in glucose levels during the dive. You should also make sure to stay hydrated on the day of your dive.
  • Consider lowering mealtime (bolus) insulin dose by around 25-33% if you plan on diving 1-2 hours after eating.
  • If you have low IOB and have not eaten in the last few hours, you may be able to have a small (around 10-15 grams) snack (such as fast-acting carbs or a low snack) before diving.
  • If you have high IOB, may want to take more carbs (such as 20-30 grams) before diving.
  • Visit our Tips for Preventing and Treating Low Blood Glucose Levels During Exercise for more recommendations.

Plan Your Dive and Communicate with Your Buddy:

• • As a person with diabetes, you should always dive with a buddy who knows that you have diabetes. The buddy should not have diabetes. Make sure your buddy knows where your devices (especially your CGM reader/phone, insulin pump, and glucose meter) and fast-acting carbs are for after the dive.
  • Before a dive, agree on a special hand signal with your dive instructor or dive buddy if you start to feel low during the dive. You might make an “L” with your hand or tap your arm where your CGM sensor is. Like other dive pre-checks, plan to go over this before every dive. This signal should be different from other safety signals used while diving.^{Jendle JH, Adolfsson P, Pollock NW. Recreational diving in persons with type 1 and type 2 diabetes: Advancing capabilities and recommendations.}

Glucose Levels During the Dive:

• • You will not be able to see your glucose levels during your dive, even if you wear a CGM because water blocks the Bluetooth connection.
  • Be aware that your usual signs of low glucose levels may not be the same while you are underwater. Diving is a physical activity and can be difficult, even if you are fit. Pay attention to how your body is feeling, and if you notice a fast change in body temperature, feel tired, or lose your coordination, these could be underwater signs that your glucose could be heading low.
  • Some people carry glucose supplies (such as glucose tablets, gels, fruit snacks) with them while diving. If it is safe, you can come up to the surface, take your carbs, and then continue your dive.

Dive Time:

• • Most diving tips suggest not diving for more than 1 hour ^[2].
  • As a new diver, you should plan to stick to this, because it helps you lessen your risk of lows. The longer you dive, the more activity it is, and the more likely you are to have lows.
  • As you get more experienced, you can plan for longer dives if you have stable glucose levels and do not tend to have lows during your 1-hour dives.
  • You may need more carbs before longer dives. You also should still plan and be ready to stop any dive where you feel low glucose, even if you planned for it to be a longer dive.

Glucose Levels:

• • Check your glucose levels as soon as you come out of the water and get your gear off.
  • If you are low or feel low, you should treat with carbs.

Insulin Strategies:

• • When you reconnect your pump, remember that you have been without insulin during (and likely before) the dive. If you take insulin to correct for a high glucose level after your dive, it will take around an hour before you start to see the peak insulin activity, so avoid taking multiple bolus insulin doses.
  • Like any physical activity, pay attention to your glucose levels for the next 12-24 hours after you dive.

Log Dive Details:

• • It is a good idea to log your dive, your blood glucose data, insulin dosing changes, and any fast-acting carbs that you needed the day of the dive. This will help you track trends and make any needed changes or decisions for future dives. This should include the timing of any meals around the time of the dive, so you can compare the actions you took before the dive (not just minutes before) that may have impacted your glucose levels during the dive.
  • For example, if you are not going low during dives and find yourself with higher glucose levels post-dive, you may be able to adjust your pre-dive carb intake (such as 20 grams to 15 grams) for the next dive.

Glucose Levels:

• • Your glucose levels should generally be between 126–216 mg/dL (7–12 mmol/L) before you dive. If your glucose levels are out of this range, you may need to wait to dive until your glucose levels are back in range or not changing much.
  • Using a CGM can help you know and manage your glucose levels before and after diving. You won’t get glucose readings while diving, but you can usually see CGM readings within 5-10 minutes after coming out from the water. Check your glucose levels with a fingerstick glucose meter and compare it to your CGM readings before and after each dive.

Insulin Strategies:

• • • Consider setting a higher glucose target around 1-2 hours before diving.
    • The goal is to try and start dives with low insulin on board (IOB), to reduce the risk of low glucose levels during dives.
    • Suspend and disconnect your insulin pump, including Pods (Omnipod), before diving. Reconnect your pump as soon as you can after diving to start insulin delivery and monitor glucose levels closely. These devices are not tested for deep water.

Carbs/Meals/Snacks:

• • If you eat a meal before diving, try to have it more than 3 hours before diving, to lower insulin levels in your body. Eating earlier helps lower the risk of quick drops in glucose levels during the dive. You should also make sure to stay hydrated on the day of your dive.
  • Consider lowering mealtime (bolus) insulin dose by around 25-33% if you plan on diving 1-2 hours after eating.
  • If you have low IOB and have not eaten in the last few hours, you may be able to have a small (around 10-15 grams) snack (such as fast-acting carbs or a low snack) before diving.
  • If you have high IOB, may want to take more carbs (such as 20-30 grams) before diving. However, be aware that a large snack may lead to a rise in glucose levels and increase automated insulin delivery by the system before diving.
  • Visit our Tips for Preventing and Treating Low Blood Glucose Levels During Exercise for more recommendations.

Plan Your Dive and Communicate with Your Buddy:

• • As a person with diabetes, you should always dive with a buddy who knows that you have diabetes. The buddy should not have diabetes. Make sure your buddy knows where your devices (especially your CGM reader/phone, insulin pump, and glucose meter) and fast-acting carbs are for after the dive.
  • Before a dive, agree on a special hand signal with your dive instructor or dive buddy if you start to feel low during the dive. You might make an “L” with your hand or tap your arm where your CGM sensor is. Like other dive pre-checks, plan to go over this before every dive. This signal should be different from other safety signals used while diving.

^{Jendle JH, Adolfsson P, Pollock NW. Recreational diving in persons with type 1 and type 2 diabetes: Advancing capabilities and recommendations.}

Glucose Levels During the Dive:

• • You will not be able to see your glucose levels during your dive, even if you wear a CGM because water blocks the Bluetooth connection.
  • Be aware that your usual signs of low blood glucose may not be the same while you are underwater. Diving is a physical activity and can be difficult, even if you are fit. Pay attention to how your body is feeling, and if you notice a fast change in body temperature, feel tired, or lose your coordination, these could be underwater signs that your glucose could be heading low.
  • Some people carry glucose supplies (such as glucose tablets, gels, fruit snacks) with them while diving. If it is safe, you can come up to the surface, take your carbs, and then continue your dive.

Dive Time:

• • Most diving tips suggest not diving for more than 1 hour ^[2].
  • As a new diver, you should plan to stick to this, because it helps you lessen your risk of lows. The longer you dive, the more activity it is, and the more likely you are to have lows.
  • As you get more experienced, you can plan for longer dives if you have stable glucose levels and do not tend to have lows during your 1-hour dives.
  • You may need more carbs before longer dives. You also should still plan and be ready to stop any dive where you feel low glucose, even if you planned for it to be a longer dive.

Glucose Levels:

• • Check your glucose levels as soon as you come out of the water and get your gear off.
  • If you are low or feel low, you should treat with carbs.

Insulin Strategies:

• • When you reconnect your pump, remember that you have been without insulin during (and likely before) the dive. If you take insulin to correct for a high glucose level after your dive, it will take around an hour before you start to see the peak insulin activity, so avoid taking multiple bolus insulin doses.
  • Like any physical activity, pay attention to your glucose levels for the next 12-24 hours after you dive.

Log Dive Details:

• • It is a good idea to log your dive, your glucose data, insulin dosing changes, and any fast-acting carbs that you needed the day of the dive. This will help you track trends and make any needed changes or decisions for future dives. This should include the timing of any meals around the time of the dive, so you can compare the actions you took before the dive (not just minutes before) that may have impacted your glucose levels during the dive.
  • For example, if you are not going low during dives and find yourself with higher glucose levels post-dive, you may be able to adjust your pre-dive carb intake (such as 20 grams to 15 grams) for the next dive.