Christopher Edge
Chair, UK Sports Diving Medical Committee
The ban on diving diabetics started in the mid-1970s, after an accident involving a diving diabetic. This diver had suffered from sudden onset decompression illness, but there was no evidence that his diabetic condition had contributed to this. Despite this, a complete ban was imposed on diving diabetics with the exception of those diabetics controlled by diet alone.
In the early 1990s, a further examination of the case and a review of the post-mortem results showed the presence of a patent foramen ovale (PFO, a hole-in-the-heart between the right and left atria) in the diabetic diver, which may or may not have contributed to this particular incident. Further, a survey was carried out on those diabetic divers who were still diving (despite the ban) and this showed that none of these diabetics had suffered from an increased incidence of decompression illness or, more importantly, suffered from hypoglycaemic attacks whilst diving. Therefore, in 1992, the British Sub-Aqua Club decided to readmit diabetics into the Club, provided that certain strict medical criteria were met.
To be allowed to dive, the diabetic must not only satisfy medical criteria, but he or she must take additional precautions when diving, both to ensure the well-being of him/herself and also the well- being of the diving buddy and the rest of the party of divers. These conditions are set out below.
The diver should not have any of the long-term complications of diabetes. The medical conditions apply equally to insulin-dependent and non-insulin-dependent diabetics. Although hypoglycaemia is a relatively uncommon complication in non-insulin-dependent diabetics the risks are not negligible and any potential diver should be using a short-acting anti-diabetic drug, if such medication is necessary. However, it does appear that non-insulin-dependent diabetics can generally exercise without fear of a deleterious metabolic response. The diving clubs in the U.K. (BSAC, SAA and SSAC) issue a common set of forms for the diabetic and his/her diabetologist to complete which ask if any of the following statements are true:
The diabetologist is also asked to comment whether in his/her opinion, the diabetic is in any way mentally or physically unfit to undertake the degree of strenuous exercise that scuba-diving demands. If the answer to any of these questions is "yes" then the diabetic would not normally be allowed to dive. An exception is normally made if the diabetic has only mild background retinopathy. The diabetic must undergo a complete physical examination on an annual basis and be passed as fit to dive by a physician with a special interest in scuba diving after reviewing the answers to the questions posed above. In addition, for diabetic divers over the age of 50, an exercise ECG is mandatory. Finally, a copy of the forms is sent to Dr. Chris. Edge in order that a database can be built up on the diabetic divers for future reference.
The diabetic should be prepared to give an annual lecture to his/her club on the problems associated with diabetes and diving. Practical illustrations of the administration of glucose and the measurement of blood glucose are also helpful. This allows the club members to gain experience, not only with the problems specific to diabetes, but also in the handling of emergencies in eneral.
It is advisable that diabetics dive only a maximum of twice per day, and not on more than three onsecutive days. This helps to avoid the build-up of an excessive tissue nitrogen load.
The dive itself can be divided into three parts: pre-dive, dive and post-dive. There are guidelines to follow for each of these three stages which are aimed to allow the diabetic diver, his/her buddy and the club to dive safely and enjoyably.
The diving diabetic should be as fit and mentally prepared to dive as his or her non-diabetic buddy. They should preferably be wearing at all times an SOS (Medic Alert) bracelet stating that the bearer is a diabetic and also a diver and that therefore the possibility of decompression illness must be considered should the diver be taken ill. The diabetic diver should be especially careful with regard to being adequately hydrated as there is some evidence that the level of hydration affects the chances of experiencing decompression sickness. The dive marshal should be aware that the subject is a diabetic and should also be informed of the profile of the dive (plan the dive and dive the plan). The diabetic diver's buddy should be a person who is either i) a regular diving partner and who is familiar with the diabetic and the problems he or she is likely to experience or ii) a trained medic or paramedic who is familiar with the problems of diabetics. Clearly, the buddy should not also be diabetic. The diabetic should carry with them on a dive a kit consisting of:
Diabetics should plan to carry glucose tablets or paste with them in a small waterproof casing or bag during the dive. The diving buddy must know the whereabouts of these tablets or paste and be able to gain access to it quickly in the event of an emergency. It is essential that there is at least one person in the dive party of the diabetic who is able to use and administer the glucose tablets and intramuscular injection of glucagon. Just prior to diving, it is sensible for the diabetic diver to ensure that he or she has a slightly higher than normal blood sugar level by consuming glucose in whatever form takes their preference (glucose tablets, barley sugar sweets etc.). Blood glucose should be measured at this time.
A diabetic diver should not dive deeper than 30 metres until a considerable experience of diving and its associated problems has been gathered by the Medical Committee. He or she should remain well within the tables or have more than 2 minutes no-stop time left on a dive computer.
On arrival back at the boat (or on shore if a shore-dive) the diabetic must check his/her glucose level and, if necessary, correct it in the appropriate manner. Any adverse symptoms or signs should be reported immediately either to the diving buddy or to the dive marshal and should not be passed off as merely "part of diving". The instructions to the diabetic diver and the diving officer are at pains to emphasise that the symptoms of low blood sugar may mimic those of neurological decompression illness or a gas embolism and vice-versa, e.g. confusion, unconsciousness, fits. In this situation, first aid therapy must be given to the diabetic casualty as though both conditions were present i.e. 100% oxygen and treatment for low blood sugar. In the event of there being an incident in the water or on the boat, the diabetic diver should be brought to the boat or shore as soon as possible. The blood glucose should be measured using the equipment in the diabetic emergency kit if this can be swiftly performed. Oral glucose should be administered to the subject with low blood sugar if conscious; otherwise, an intramuscular injection of glucagon (1 mg) should be given. Medical attention and recompression facilities should be sought as soon as possible.
Since November 1991, the Medical Committee has allowed more than eighty diabetic divers to dive. The age range is approximately 17-50. Both insulin-dependent and non-insulin-dependent diabetics are registered. Currently, there are three National Instructors (the highest teaching grade within the BSAC) who are registered. So far (February 1995) there have been no diving deaths attributable to diabetes and only two reported incidents of mild hypoglycaemia in the water (both incidents were on the surface and the divers reported feeling slightly light-headed; both were able to correct this using the glucose paste that they carried). As of March 1994, 702 person dives had been logged with 220 in the depth range 0-10 metres, 252 in the range 11-20 metres, 165 at 21-30 metres and 65 over 30 metres. 31 of these dives involved decompression stops.
The Medical Committee hopes that the standards set out above are such that adherence to them will allow certain diabetics to dive safely and enjoyably. The situation is kept under constant review, but so far appears to work reasonably well. The Committee has had enquiries about the standards from the U.S., Egypt, Denmark, Holland, Saudi Arabia, Australia and Cuba and it appears that several diving organisations may adopt them in the future.
Enquiries to:
Dr. C.J. Edge, The Stone Barn, Gravel Lane, Drayton, Abingdon, Oxon. OX14 4HY
Tel. +44-1235-529-888
e-mail: cjedge@vax.ox.ac.uk or edge_c@snd02.pcr.co.uk or 100117.3646@compuserve.com
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