Scuba Diving with Diabetes: Uses, Benefits, and Side Effects

Scuba diving with diabetes was effectively banned by major training agencies (PADI, NAUI, SSI) for decades because of fears about underwater hypoglycemia. That changed when the Divers Alert Network convened a 2005 workshop and published evidence-based guidelines that codified eligibility, pre-dive targets, and emergency response. Today, recreational diving with both type 1 and type 2 diabetes is widely available, with thousands of certified divers worldwide. This guide covers the DAN criteria, pre-dive glucose targets, signaling, pump considerations, and the differences between recreational and technical diving.

The DAN Guidelines in Brief

The 2005 DAN workshop and subsequent updates set out three categories of criteria:

• Selection criteria — who can dive at all
• Glucose management criteria — what glucose level is acceptable for a dive
• Operational criteria — what the dive itself must look like

Selection Criteria

Pre-Dive Glucose Protocol

1. Check glucose 60 minutes before the dive
2. Target: 150 to 300 mg/dL (8.3 to 16.7 mmol/L)
3. If below 150 mg/dL: ingest 15 to 30 grams of carb, recheck in 15 minutes
4. If above 300 mg/dL: do not dive — check ketones, address with insulin and fluids, postpone
5. Recheck at 30 minutes pre-dive
6. Recheck immediately before splash if a long surface interval
7. Glucose trend matters: a falling trend in target range may warrant a small pre-dive snack

Equipment and Signaling

• Glucose gel tubes in BC pocket — 2 tubes minimum, sealed and accessible underwater
• Bright dive flag or marker indicating “diabetic diver” on registration form (optional but common)
• Buddy briefed on the agreed hypoglycemia signal — typically a fist on top of the head or wrist tap
• “OK” signal exchange every 10 to 15 minutes during the dive
• Continuous glucose monitor (CGM) sensor on torso — sealed sensors (Dexcom G7, FreeStyle Libre 3) survive recreational depths; the transmitter signal does not transmit underwater but the historical data downloads at the surface
• Medical ID engraved on tank or BC strap

Insulin Pump Considerations

Most pump manufacturers do not approve underwater use:

• Tandem t:slim X2 — rated to 3 feet (1 m) for 30 minutes; not approved for diving
• Medtronic 770G / 780G — not waterproof for diving
• Omnipod (Insulet) — pod is rated to 25 ft (7.6 m) for 60 minutes; some divers wear at shallow depths off-label
• Ypsomed mylife YpsoPump — not approved for diving

The two practical approaches:

1. Disconnect pre-dive. Take a partial dose of long-acting insulin (Lantus or Tresiba) 24 hours pre-dive in a quantity equivalent to the basal that will be missed. Reconnect post-dive.
2. Suspend pre-dive. Short single dives — suspend the pump, leave it on (if pod) or remove it (if tubed), reconnect immediately on surface. Risk-acceptable for 30 to 45 minute dives in stable basal-pattern divers.

Risk-Sensitive Procedures

• No alcohol within 12 hours pre-dive
• Adequate sleep — fatigue worsens hypoglycemia perception
• Adequate hydration — dehydration affects decompression risk and glucose
• Surface interval glucose check between dives
• No diving after a recent insulin-dose change
• Conservative dive profile — no decompression stops on recreational dives
• Maximum depth typically 30 m / 100 ft for diabetes divers in many programs
• Diving with a properly briefed buddy, never solo

In-Water Hypoglycemia Response

1. Signal the buddy — fist on head
2. Buddy confirms and initiates ascent
3. Controlled ascent at normal rate (60 ft/min or slower per agency standards)
4. Safety stop completed if depth allows
5. At depth around 5 m / 15 ft, take glucose gel from BC pocket — inject into mouth around the regulator
6. Surface together
7. Oral fast-acting carb at the surface
8. Re-check glucose on the boat or shore
9. Do not dive again that day if a hypoglycemia event occurred underwater

Recreational vs Technical Diving

The DAN Examination Form

Before certification or charter operator clearance, divers with diabetes typically complete the DAN/UHMS Medical Examination Form including a diabetes-specific addendum. The form is reviewed by the dive operator’s medical advisor or a DAN-affiliated physician. It is updated annually or per the operator’s policy.

Common Logistical Tips

• Bring printed copies of the medical form on every trip — international charter operators may not have a translated version
• Letter from clinician describing diabetes management on letterhead helps clear airport security with insulin and needles
• Insulin storage on dive boats — request a fridge or bring a small FRIO wallet
• Time zone changes affect basal/long-acting insulin timing for dive vacation travel
• Glucagon should accompany the dive bag — usable on the surface only

Related Reading

For travel-temperature insulin storage planning see our piece on camping with diabetes. For physical activity planning generally see our marathon running with diabetes guide. For broader context on diabetes and complications relevant to dive eligibility see complications and related conditions and our overall treatment overview.

The Bottom Line

Recreational scuba diving with diabetes is a permitted activity under the well-established DAN Diabetes and Diving Guidelines, with thousands of safely certified divers using the framework worldwide. The non-negotiable elements are A1C under 9%, no severe hypoglycemia in the past 12 months, intact hypoglycemia awareness, ophthalmology clearance if any retinopathy exists, a pre-dive glucose target of 150 to 300 mg/dL, a briefed buddy with an agreed signal, and accessible glucose gel in the BC pocket. Insulin pumps are typically disconnected for the dive with a long-acting bridge. Technical and commercial diving carry additional restrictions. With clinician clearance and a careful protocol, diving is no more risky for a person with diabetes than for anyone else of similar fitness.