Recreational diving and diabetes

I recently attended the annual Wilderness Medicine Society meeting in Colorado. There, Dr. Eric Johnson gave an informative presentation — Update in Dive Medicine — during which he reviewed guidelines for recreational diving for people with diabetes.

I am not a diver myself. Thus, until now, I have not given much thought to the subject. However, many of my patients are divers. Because most endocrinologists are not experts in diving medicine, I thought it would be helpful to review these guidelines:

Selection and surveillance:

Divers with diabetes should be aged 18 years and older (or 16 years and older if in a special training program).
Diving should be delayed after start/change in medication: 3 months with oral hypoglycemic agents; 1 year after initiation of insulin therapy.
No episodes of hypoglycemia or hyperglycemia requiring intervention from a third party for at least 1 year.
No history of hypoglycemia unawareness.
HbA1c of 9% or lower no more than 1 month prior to initial assessment and at each annual review.
No significant secondary complications from diabetes.
Diabetologist should carry out annual review and determine that diver has good understanding of disease and effect of exercise (with consultation with an expert in diving medicine, as required).
Consider evaluation for silent ischemia for candidates aged older than 40 years after initial evaluation and periodic surveillance.
Candidate should document intent to follow protocol for divers with diabetes and to cease diving and seek medical review for any adverse events during diving possibly related to diabetes.

Scope of diving:

Diving should be planned to avoid: depths greater than 100 feet of salt water; durations longer than 60 minutes; compulsory decompression stops; overhead environments such as caves and wrecks; situations that may exacerbate hypoglycemia such as prolonged cold and arduous dives.
Dive buddy/leader informed of diver’s condition and steps to follow in case of problem.
Dive buddy should not have diabetes.

Glucose management on the day of diving:

General self-assessment of fitness to dive.
Blood glucose of 150 mg/dL or greater stable or rising, before entering the water.
Complete a minimum of three pre-dive blood glucose measurements to evaluate trends 60 minutes, 30 minutes and immediately prior to diving.
Consider possible alteration in dosage oral hypoglycemic agents or insulin or evening prior or day of diving if necessary.
Delay dive if blood glucose is less than 150 mg/dL or greater than 300 mg/dL.
Rescue medications: carry readily accessible oral glucose during all dives; have parenteral glucagon available at the surface.
If hypoglycemia is noticed underwater, the diver should surface (with buddy), establish positive buoyancy, ingest glucose and leave the water.
Check blood glucose frequently for 12 to 15 hours after diving.
Ensure adequate hydration on days of diving.
Divers should log all dives (include blood glucoses and all information pertinent to diabetes management).

Unrecognized hypoglycemia while underwater is the greatest concern for divers with diabetes. However, with appropriate screening and monitoring, diving with diabetes appears to be safe. The Divers’ Alert Network collected data on 561 dives by 41 insulin-requiring divers from 1997 through 1999. There was no hypoglycemia or other adverse events during diving in divers with diabetes. There were 18 hypoglycemic episodes outside of diving.

For more information:

Pollock NW. Diabetes and recreational diving: guidelines for the future. Proceedings of UHMS/DAN 2005 June 19 Workshop. Durham, NC: Divers Alert Network; 2005.