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Endocrine and Metabolic Problems


Diabetes and Diving
The Thyroid and Diving
Chronic Adverse Effects of  Diving :
Genetic and Reproductive

Related Web Pages on Our Site
Dehydration, Diuretics and Diving

Nutrition and Diving
Physical Fitness and Sports Diving
Exercise, Diving and the Heart
Obesity and Diving

Diabetes and Diving

Diabetes Mellitus: Insulin dependent diabetics represent a gamut of severity; from the more brittle diabetic who should not dive to a less serious one which should not increase the hypoglycemia risk enough to exclude diving. The long-standing diabetic who has lost the normal defense mechanism against hypoglycemia should not dive. Newer methods for testing and steps to regulate blood sugar can eliminate the risk of hypoglycemia. As diabetics are more prone to coronary disease, a good physical examination, and exercise testing when indicated, can reduce the risk for a heart problem while diving.

Guidelines From DAN for Diabetics Who Want to Dive

DAN suggests that some diabetics may dive safely in controlled settings.

• Age ≥18 years (16 years if in special training program)

• Delay diving after start/change in medication
- 3 months with oral hypoglycemic agents (OHA)
- 1 year after initiation of insulin therapy

• No episodes of hypoglycemia or hyperglycemia requiring intervention from a third party for at
least one year

• No history of hypoglycemia unawareness

• HbA1c ≤9% no more than one month prior to initial assessment and at each annual review
- values >9% indicate the need for further evaluation and possible modification of therapy

• No significant secondary complications from diabetes

• Physician/Diabetologist should carry out annual review and determine that diver has good
understanding of disease and effect of exercise
- in consultation with an expert in diving medicine, as required

• Evaluation for silent ischemia for candidates >40 years of age
- after initial evaluation, periodic surveillance for silent ischemia can be in accordance with
accepted local/national guidelines for the evaluation of diabetics

• Candidate documents 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 >100 fsw (30 msw)
- durations >60 minutes
- compulsory decompression stops
- overhead environments (e.g., cave, wreck penetration)
- situations that may exacerbate hypoglycemia (e.g., 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 (BG) ≥150 mg·dL -1 (8.3 mmol·L -1 ), stable or rising, before entering the water
- complete a minimum of three pre-dive BG tests to evaluate trends
  60 minutes, 30 minutes and immediately prior to diving
- alterations in dosage of OHA or insulin on evening prior or day of diving may help

• Delay dive if BG
- <150 mg·dL -1 (8.3 mmol·L -1 )
- >300 mg·dL -1 (16.7 mmol·L -1 )

• Rescue medications
- carry readily accessible oral glucose during all dives
- have parenteral glucagon available at the surface

• If hypoglycemia noticed underwater, the diver should surface (with buddy), establish positive
buoyancy, ingest glucose and leave the water

• Check blood sugar frequently for 12-15 hours after diving

• Ensure adequate hydration on days of diving

• Log all dives (include BG test results and all information pertinent to diabetes management)

For full text see: Pollock NW, Uguccioni DM, Dear GdeL, eds. Diabetes and recreational diving:guidelines for the future. Proceedings of the UHMS/DAN 2005 June 19 Workshop. Durham, NC: Divers Alert Network; 2005.

The Diabetes and Diving Committee of the Council on Exercise of the American Diabetes Association notes that there are currently a substantial number of diabetics, in the United States and elsewhere, who dive.

Criteria for diving include:
good control of blood glucose levels
freedom from severe secondary complications of diabetes (eyes, kidneys, blood vessels)
an understanding of the relationship between the disease and exercise

Diabetics who shouldn't dive are those who:

have had a serious hypoglycemic episode within the past 12 months
have advanced secondary complications of the disease
have poor control of their blood sugar
are unaware of the early warning signs of hypoglycemia
lack insight into the relationship between diabetes and exercise

UKSDMC recommendations are similar, though more rigorous. A questionnaire must be filled out by the prospective diver, and a separate one completed by the diver's physician. In addition, BSAC has developed guidelines concerning what additional gear and supplies diabetic divers should carry, and proposes a pre- and post-dive plan in order to minimize risks.

The YMCA has an extensive protocol for diabetic scuba divers. It carefully differentiates the divers with mild diabetes and those with frequent changes in blood sugar levels and hypoglycemia.

Diving Programs for Diabetics
PADI Medical Checklist
Doc's Diving Page

DAN Articles on Diabetes & Diving
      Blood Glucose Response to Recreational Diving in Insulin-Dependent Diabetics
      DAN examines Diabetes Guidelines
Diabetes and Diving -- An article on current practices

Hyperbarics and Diabetes

Dermagraft For Diabetic Foot Ulcers
Dermagraft, a living human dermal replacement for the treatment of diabetic foot ulcers.

Hyperbaric Oxygen Therapy
From the Undersea and Hyperbaric Medical Society, learn about a therapy known to help healing in the case of those with diabetes. Contact information available.

The Role of HBO Therapy in Diabetes
Just how does hyperbaric oxygen therapy relate to a diabetes ulcer or wound?  From Wound Care Consultants.

The Thyroid and Diving

The thyroid gland secretes thyroxin which is a hormone that helps control the rate at which we burn up carbohydrates (metabolic rate). Too much thyroxin causes hyperthyroidism (thyrotoxicosis) --- too little causes hypothyroidism (myxedema).

What a diver needs to be concerned with is his/her body's ability to function with the increased work load that hyperthyroidism places on your heart. Add to this increased workload the load of diving with heavy gear and your heart may not be able to handle it, in that the person with hyperthyroidism is prone to having attacks of paroxysmal atrial tachycardia or atrial fibrillation (episodes of rapid heart beating) that can leave the person unconscious or unable to function. This would be disastrous under water, even if you were just skin diving or snorkeling.

Atypical presentation, with cardiac or psychiatric symptoms, is common in men. Patients with thyroid ophthalmopathy frequently have difficulty in upward gaze. Corneal damage and optic neuropathy (inflammation of the optic nerve) can also occur.

Return to diving: Return to diving may be considered once the patient is euthyroid (normal thyroid level) on a stable dose of replacement medication if required. Patients with ophthalmopathy will need to be disqualified while undergoing treatment and may need to be disqualified permanently if treatment is unsuccessful. Mask damage to the eye is a strong possibility in these situations.

Data required for decision making: Endocrinology consultation, appropriate laboratory studies and ophthalmological consultation is also required if exophthalmos (protrusion of eyes) or other eye conditions are suspected. Annual confirmation of clinical and chemical euthyroid (normal) status is needed for continued diving.

Therapy: There are 3 main forms of therapy: medical treatment with methimazole or similar drugs; radioactive iodine; and surgery. Methimazole may cause side effects including vertigo and drowsiness, as well as agranulocytosis (bone marrow suppression). Diving is contraindicated in when their is bone marrow suppression due to the possibility of increased infections. Surgery is declining in popularity but may be the treatment of choice in females of childbearing age, because of the possibility of ovarian damage from the radioactivity. A small number of cases will require eye surgery.

Notes for consideration of the diver: Muscle pain, weakness and stiffness are the presenting symptoms in 25% of patients. Weakness and tremor can be mistaken for decompression accidents. Bulbar involvement can occur. With drug treatment, there is a 50% relapse rate, some cases relapsing early. With radioactive iodine, 10 to 15% of cases will be hypothyroid (low thyroid condition) within 2 years, and 50 to 60% will be hypothyroid within 20 years. A third of patients undergoing surgery will be hypothyroid within 10 years. Patients therefore have to review regularly for the rest of their lives. The complete remission rate (those that get well) after radioactive iodine is 86% with 60% developing myxedema (puffy swelling of low thyroid condition) after 10 years and a further 2-3% a year developing myxedema after that. Only 5% of patients with Graves' disease (hyperthyroidism) will have ophthalmopathy (protruding eyes). More than 50% of cases of exophthalmos (protruding eyes) will get better spontaneously  within 5 years with no other treatment than that of the underlying condition. Only 5% of patients will require eye surgery.

Nitrox Diving and the Thyroid

Nitrox is the mixture of increased amounts of oxygen in the breathing air of divers. Regular air is 20%; nitroz is mixed in 32%, 36% and higher. This allows for longer bottom times, reduced risks of decompression illness (less nitrogen) but also imposes a penalty of increased risk of oxygen toxicity. Certain drugs are sympathomimetic (mimicking the action of the sympathetic nervous system) and increase the metabolic rate, heart rate and rate at which O2 is utilized. Thyroid hormone, either Synthroid or thyroxin produced by the body or taken by mouth act in this manner. These drugs also have been found to increase the risk of oxygen seizures at shallower depths (pressures).
See Nitrox at http://www.scuba-doc.com/nitrox.htm or

For a good discussion of thyroid conditions, go to this web page

To my knowledge there have been no studies that have shown any increased risks to the person with hyperthyroidism, even untreated. However, the prudent person would certainly not dive if his thyroid functions were out of line --- just as he/she should not play tennis or handball or some other physical exercise until they were "euthyroid" (normal function of the gland). One month of treatment is not usually long enough to become euthyroid -- although I've had patients who have responded rapidly to medication. Your doctor should be the final arbiter in this matter.


One other symptom that you need to be aware of is exophthalmos (see above), or protrusion of the eyes. This can occur in one or both eyes in association with a high thyroid condition. If this is a prominent part of your illness, then you need to be concerned with mask squeeze and with irritation of the cornea.

See Eye problems

Chronic Adverse Effects of Diving on Genetics and Reproduction


In a study which was funded by the U.K. Departmentof Energy (Fox et al, 1984) blood was taken from more than 150 divers and an equal number of control subjects. Of 77 compressed air divers and 76 mixed gas divers, 6 had a few heavily damaged cells. The health risks imposed by these abnormal cells is unknown but the damage they contain is, in most cases, so extreme that they are likely to die at mitosis. No such cells were found in the controls.

This type of finding was unexpected and, because of such low numbers, no correlation was possible with the many associated occupational factors that were also studied. The aberrations observed were typical of those induced by ionizing radiation and were present in air divers as well as mixed gas divers.

In addition, changes have been reported in lymphocytes and heat shock protein expression in divers in the UHMS publication, Undersea and Hyperbaric Medicine.

Undersea Hyperb Med 2000 Spring;27(1):37-41
Hyperbaric stress during saturation diving induces lymphocyte subset changes and heat shock protein expression.

Matsuo H, Shinomiya N, Suzuki S

Department of Microbiology, National Defense Medical College, Tokorozawa, Japan.

To clarify the cellular responses and biochemical markers of hyperbaric stress, we investigated heat shock protein (hsp) expression and subset changes of human peripheral blood lymphocytes during saturation diving. Five healthy male subjects underwent a 39-day saturation dive to the maximal storage pressure of 4.1 MPa [400 meters of sea water (msw)]. During the saturation dive, lymphocyte subset changes were detected using a flow cytometer, and increased expressions of hsp 72/73 and hsp 27 were observed by Western blot analysis. Lymphocyte subset changes included a decrease in CD4:CD8 ratio and in the fraction of CD4+ T cells as well as an increase in NK cells, especially during the 400-msw bottom phase. An increased expression of hsp 27 compared to hsp 72/73 was obvious, especially during the hold period at 100 msw. These results suggest that changes in lymphocyte subsets and hsp expression are useful markers for stress responses during saturation diving. These changes may also be useful for testing the barotolerance of divers for saturation diving.
Other references to lymphocyte suppression and diving are located at

Shinomiya N, Suzuki S, Hashimoto A, Oiwa H.
Effects of deep saturation diving on the lymphocyte subsets of healthy divers.
Undersea Hyperb Med. 1994 Sep;21(3):277-86.

There are also many other possible long-term effects such as subfertility in animals (Hawley et al, 1986), an effect recently studied in man and reported in the International Journal of Andrology.

Int J Androl 2000 Apr;23(2):116-20
Impact of a deep saturation dive on semen quality.

Aitken RJ, Buckingham D, Richardson D, Gardiner JC, Irvine DS

MRC Reproductive Biology Unit, 37 Chalmers Street, Edinburgh EH3 9ET, Scotland. jaitken@mail.newcastle.edu.au

The demonstration dive 'Aurora' has provided an opportunity to study the impact of extreme hyperbaric conditions on male fertility. This operation involved a 33-day diving programme during which divers were exposed to a maximum pressure of 4.6 Mega Pascals (Mpa) for 7 days. At days - 4, + 27, + 34, + 82 and + 263 relative to the initiation of the dive, semen samples were analysed to determine the quality of spermatogenesis and the functional competence of the spermatozoa. A dramatic fall in semen quality was observed in association with the dive and by day + 82 the potential fertility of the men was seriously compromised as evidenced by oligoasthenoteratozoospermic semen profiles and the poor fertilizing potential of the spermatozoa. These studies indicate, for the first time, that the severe hyperbaric conditions associated with deep saturation dives have a profound effect on male reproductive function.

Diving and fertility

Few areas of military activity seem to generate as much myth and legend as diving. It is a common belief that male divers offspring tend to be female, and the mechanism for this is often quoted as a hyperbaric effect on testicular perfusion. In an unpublished study, Edmonds conducted a retrospective review of Royal Australian Navy divers offspring. Of 240 offspring, 122 were conceived before diving activities, the remaining 118 after the divers received their diving qualifications. Edmonds further divided these groups into air divers and oxygen divers and generated 2 contingency tables that were analysed by chi2 test. There was no significant difference between the groups and no support for the hypothesis that divers have a propensity to female offspring (Edmonds, quoted by Commander Robyn Walker, personal communication)

ADF Health
Vol 2 September 2001

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 Ernest Campbell, MD, FACS All Rights Reserved.

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Home > Endocrine and Metabolic Problems

Medline || Bookstore || Conferences || Email Us || Contact Us || Glossary || Links || Scuba Clinic Forum  || Tenfootstop Weblog || FAQ