Most diabetics know more about their disease than their doctors but I think an overview is necessary here.
Please forgive me if I am teaching my granny to suck eggs.
There are two types of diabetes.
Type I, insulin dependent diabetes develops rapidly in young people and results from a complete failure of the pancreas to produce any insulin. These patients must use insulin to keep them alive. These patients are also known as suffering from
Insulin
Dependent
Diabetes
Mellitus (IDDM).
The western world is suffering an epidemic of the second kind of diabetes, type II or
Maturity
onset
Diabetes. (MOD) caused by insulin resistance and associated with junk food and obesity and treated with diet and tablets at first.
Diabetes does not just affect blood sugar, it is a multisystem disease affecting the eyes, kidneys, heart and peripheral nerves. Diabetes is a common pre-cursor of ischaemic heart disease. The BSAC consider diabetes with any of these complications is an absolute contraindication to diving. They recommend referral to a medical referee for all diabetics and for other endocrine disorders and an annual dive medical is mandatory.
Diving with diabetes
No recreational scuba diving is risk free. The main additional risk of diving with diabetes is low blood sugar (a "hypo") with resulting unexpected loss of consciousness. But diving is still relatively safe for diabetics whose blood glucose levels are usually within the normal range, who don't have associated complications, and who record their blood glucose and precisely know how exercise affects it. There exist a subgroup of diabetics whose blood sugars are difficult to control or predict. These are commonly known as brittle diabetics and are obviously at greatest risk. This is the group who benefit most from the use of an insulin pump, as opposed to multiple daily injections.
Diving is not safe for people who don't meet the above criteria. Low blood sugar is not the only problem. High blood sugar will, due to too little insulin, cause an uncontrollable diuresis (urine production) leading to even more dehydration than the normal immersion diuresis which, we all know, increases the risks of DCI.
The following list describes in more detail situations in which diving is not safe for people with diabetes:
[*]It is unwise to dive if you are prone to impaired judgement, lack of physical coordination, or seizures during episodes of low blood sugar.
[*]You are very unwise to dive if you cannot sense the initial warning signs of a hypo or if you have recently had a hypo that required someone's help to recognise or treat it. A severe hypo can also cause permanent brain damage.
[*]Like any physical activity of over 4 METS , scuba diving will lower blood glucose levels so diving should be avoided if this level of exercise causes low blood glucose.
[*]HbA1c levels, give an idea of average blood glucose control over the preceding two to three months, but in my opinion HbA1c cannot be relied upon as an indication that a diabetic is safe to dive.. For example, three consecutive abnormal monthly blood glucose readings of 17,3 and 8 mmols will give an near normal average of 9.3 mmol and quite possibly a misleadingly normal HbA1c, when it is clear that this person is a brittle diabetic and at added risk.
[*]The complications of diabetes such as neuropathy (nerve damage), nephropathy (kidney disease), advanced retinopathy (eye disease), or ischaemic heart disease (heart problems) prohibit diving. It is almost a certainty that poor microcirculationwhich is the precipitating cause of these complications will hinder offgassing.
For your own safety, but to my mind more importantly the safety of others, it is imperative to talk about your diabetes with your dive buddy and dive marshal or instructor. You must explain what a hypo is, why it happens, what you can do to prevent it, how you can treat it and take a source of glucose and a glucagon injection with you on every trip. You should describe the signs of low blood sugar, especially those that would be apparent even underwater, such as shakiness, irritability, impatience, stubbornness, lack of coordination, and other strange behaviour.
Few scuba instructors and dive marshals know much about diabetes or the risks divers with diabetes face. You may find that some are not willing to accept the liability of taking a person with diabetes on a dive trip. This makes it tempting to avoid telling anyone that you have diabetes, but one only has to imagine that since the dive marshal doesn't know you have diabetes, he may plan a dive that's longer or more vigorous than you expected, which could lead to a hypo underwater. And, of course if you hide your diabetes, you will be unable to check your blood glucose level at the times you must.
I think diabetic divers would be wise to check their blood sugar as many as 12-15 times per day especially on a trip, thus learning how scuba diving and other forms of exercise affect their levels.
In spite of the risks of a slightly high blood glucose, preventing a hypo and being able to treat it properly are the most important considerations. Thus a highish level is wise pre-dive and it is important to do one check an hour before the dive, another 30 minutes before the dive, and a third just before entering the water to determine the trend and ensure it is not likely to fall to dangerously low levels. A stable pre-dive level of at least 8 mmol (180 mg/dl) is desired.
If the trend is downwards the dive must be aborted or postponed. A glucose-rich confection should be eaten and a further checks made to ensure blood glucose levels have returned to,and stay at, safe levels. It is also wise to make a note of what was eaten that day and keep these results, and that from an immediate post-dive check, with your dive log for future planning.
*All mechanical devices can fail and I consider
an insulin pump should not be used underwater as this will add to the risks of blood glucose falling to dangerous levels.
There are many sources of almost neat glucose to treat hypos. I prescribe Hypo-stop and glucagon for my own insulin dependent diabetics, none of whom dive. Honey in a plastic bottle or tube or icing sugar in a plastic tube with a screw top also works and it is wise that a source of glucose is also added to the first aid kit.
Obviously the dive must be called at any point if a diabetic or their buddy suspects a hypo.
This could be confused with narcosis and a very low threshold is recommended. Before the dive, make sure the buddy understands the added problems he faces, accepts the added responsibility and is willing to cut his dive short. It is wise to have a specific signal to instantly warn yourselves of a suspected hypo. Making an "L" with thumb and index finger is an unmistakable sign to use following which you must surface and take a minimum of 15 g glucose. In my opinion IDDM divers ought not to undertake technical diving because of this, but I suppose there is nothing to prevent a supply of glucose being taken on the dive to take immediately on surfacing.
Please take this as intended, an overview of the subject and is not aimed at any particular individual.
:doctor:
* edited on 12 /4/03
