All of us tend to take normal, good health very much for granted and probably never give it a second thought; that is until we enroll in an activity to which certain restrictions may be attached. Recreational scuba diving in the UK is one such sport.
Many of you will be familiar with the UK Sport Diver Medical Form and know that it makes recommendations and gives guidelines regarding the conditions with which a person may or may not pursue the sport of recreational scuba diving. Diabetes mellitus (DM) is one of the conditions listed on the medical form.
Diabetes mellitus is present in about 3% (2.5% known, 0.5% unknown) of the UK population. It is characterised by excessive thirst, polyuria and a high fasting blood glucose. The current treatment for DM may be diet, oral administration of tablets or insulin injection. Administration of tablets (particularly those with a long half-life) or of insulin, without adequate intake of glucose, may lead to low blood sugar, altered thinking, fits, coma, and death within a short period of time.
Hypoglycaemia (low blood sugar) may be treated by the oral administration of glucose (either in solid or liquid form) if the patient is conscious, or by the intramuscular injection of glucagon. It is this risk of hypoglycaemia occurring in a situation in which administration of glucose or glucagon is delayed, thus leading to unconsciousness and death in the diver with DM, that has caused most of the scuba-diving agencies throughout the world to ban diabetics from the activity of scuba-diving. There is also the risk to the diving buddy from having to rescue a hypoglycaemic diver from under the water or on the surface. The odd case has been reported in which the symptoms of decompression illness presenting in the diabetic diver have been confused with the symptoms of hypoglycaemia, and this has lead to a delay in recompression therapy for the affected diver, resulting in permanent spinal paralysis in one particular case.
During the course of the last decade, several advances have been made in the treatment of DM, such as the development of small, portable glucometers that allow fast and accurate measurements of blood glucose to be made by the diabetic themselves, and the use of rapidly acting insulin in portable pen-like syringes, thereby allowing more frequent and accurate dosing with insulin. In 1991 these advances caused the BSAC, the SAA and the SSAC to revise their past policies, which was that of refusing to allow diabetic people to dive.
The current recommendations now are that certain well-controlled diabetic persons, without long-term complications of DM, are allowed to dive provided that they are able to pass a medical test of fitness, the consultant diabetologist or practitioner in charge of the diabetic person has reviewed his/her medical results, and a medical referee from one of the three diving agencies has passed the diabetic person as fit to dive and completed the UK Sport Diver Medical Form.
So - how many UK recreational divers suffer from DM? Calculating how many active recreational divers there are in the UK is difficult, but if it is assumed that there are approximately 90,000 it could be argued that there is a theoretical upper limit to the number of divers with DM in the UK of >2,700 and a lower limit which could be as high as 500. At present there are no data on the total numbers of divers with DM.
And this is where the current DDRC Diving and Diabetes study enters the scene. In order to be able to substantiate the claim, "that it is safe for divers with well-controlled DM to scuba dive", there is a vital need to gather more information concerning diving and DM. The only way this can be achieved is from divers with DM! In the past the DDRC have conducted controlled trials in the recompression chambers with divers who suffer from DM.
Drs Phil Bryson and Chris Edge examined the effect of a single simulated dive in a dry hyperbaric chamber at 3.7 ATA compared to a control simulated dive at 1 ATA on both diabetic and normal divers. No adverse events were recorded in that study by either control or diabetic divers. The Divers Alert Network (DAN) in the USA is also attempting to collect data on the subject of diving and DM. In 1991 a questionnaire pilot study was initiated by Dr Chris Edge which demonstrated the benefit of gathering long term data from people with DM who wish to, or already, scuba dive. Because it was apparent that much valuable data could be gathered from this study, the project was expanded in 1995, and it is now run from the DDRC, Plymouth, UK.
The study takes the form of a questionnaire which is administered, on an annual basis, to those diabetic divers who wish to dive. It is unique because it is the only study, to our knowledge, currently being conducted where data is being gathered from divers doing "real life" diving as opposed to controlled chamber dives or monitored sea dives over a one or two week period. Although the study has over 200 divers on the data base (18% females and 82% males), this is less than the number expected, assuming the numbers given above, though one has to take into account the effect of the pre 1991 rulings preventing divers with DM to dive in the past.
Dialogue with dive school operators and dive clubs has confirmed that some divers with diabetes are reluctant to make themselves known to the project and/or submit themselves for an annual medical believing that they may be prevented from diving in the future. The message the DDRC study urgently needs to get across is that this is not the case. Only with many diabetic divers taking part will it be feasible to prove to the sceptics that divers with well-controlled DM can dive as safely as divers not suffering from DM.
On a positive note the DDRC has already published some preliminary findings with the study attracting much interest amongst the diving research fraternity. The number of divers joining the study increases every year with a wide age range, currently 18 to 69 and an equally wide range of experience, from novice divers to "old bold divers" with more than 1,500 dives under their belts!
So please, in order to promote safer diving, an awareness of the implications of diving and diabetes and to help us gather as much data as possible, we hope if you suffer from DM and dive, or you know of any diver with DM, and you or they are not in the study that you will contact:
DDRC, Hyperbaric Medical Centre, Tamar Science Park, Derriford Rd, Plymouth, Devon, UK. Phone +44 (0) 1752 209999 Fax +44 (0)1752 209115 and enroll.
NOTE: Scuba Diving and Diabetes is a DDRC project headed up by Dr Chris Edge with Dr Phil Bryson, Dr Alex Gunby & Marguerite St Leger Dowse.