diabetes and scuba diving

[Dr. Doug Ebersole]

Divers Alert Network had a symposium on diving and diabetes published in 2005. Here is the link:
http://www.diversalertnetwork.org/files/UHMS_DAN_Diabetes_Diving_2005_Workshop_Proceedings.pdf

The major concern with diving with diabetes is hypoglycemia (low blood sugar) and not hyperglycemia (high blood sugar). It is much better to start a dive with glucose levels a little above normal if you are diabetic. Certain agents such as insulin and glipizide are more likely to result in hypoglycemia than other agents such as metformin. Basically, if your blood sugars are well controlled and you check them before and after diving and you don't do prolonged or decompression or overhead diving where developing symptoms of hypoglycemia could be especially problematic you can dive recreationally safely. The diver with diabetes should carry some glucose with them that they could take in the event of symptoms and they and their buddy should have some sort of hand signal to communicate the diver is having symptoms of hypoglycemia. All of this being said, some dive operators may simply not let diabetics dive on their boats so it's good to check things out ahead of time.

Just my 2 cents from working with DAN -- as a cardiologist and NOT as an endocrinologist, however!

 

[NancyLynn]

Divers Alert Network had a symposium on diving and diabetes published in 2005. Here is the link:
http://www.diversalertnetwork.org/files/UHMS_DAN_Diabetes_Diving_2005_Workshop_Proceedings.pdf

The major concern with diving with diabetes is hypoglycemia (low blood sugar) and not hyperglycemia (high blood sugar). It is much better to start a dive with glucose levels a little above normal if you are diabetic. Certain agents such as insulin and glipizide are more likely to result in hypoglycemia than other agents such as metformin.

The problem with the guidelines is that they don't distinguish betweeen diabetics using agents that create a risk of hypoglycemic incidents and those that don't, and the guidelines recommend that every diabetic - even those at no more risk for hypoglycemia that people without diabetes - start the dive with 150 mg/dl blood glucose. Diabetes, in and of itself, does not create the risk for hypoglycemia - it is the additional insulin floating around (from insulin injections or from pancreatic secretions that are not triggered by food consumption - e.g. triggered by sulfonylureas) that creates the risk. Diabetics controlled by diet alone, or by diet + metformin have no more risk of hypoglycemic incidents than non-diabetics, yet are bound by the same guidelines. (By "bound" I mean that the doctors providing medical clearance are directed to ensure that the candidate "documents intent to follow protocol for divers with diabetes.")

I've seen a blood glucose number of 150 mg/dl no more than a dozen times since diagnosis a year ago. If I'm outside the normal range (140 mg/dl or above) it is because I've slipped up and had a meal higher in carbs than I intended.

I would never intentionally create a blood glucose level of 150 mg/dl. For one thing, it is noticeable to observant people around me when my blood glucose level exceeds 130 mg/dl. I am noticeably less attentive to what is going on around me, and mentally slower. That isn't a good thing at any time - and definitely a bad thing to intentionally induce at the start of a dive. For another, 140 mg/dl is the level at which chronic kidney disease and other disastrous side effects of diabetes begin. A recent study found that a large percentage of prediabetics (average below 137 mg/dl) already have undiagnosed chronic kidney disease. Yet the guidelines direct me to test my blood glucose 3 times before diving to ensure that it is 150 mg/dl or higher AND steady or rising.

The risk of having a hypoglycemic incident is absolutely an appropriate concern - it would be diastrous, and even if I were willing to risk my personal safety - the impact of dealing with the aftermath of a hypoglycemic incident on my buddy, divemasters, boat crew, etc would be monumental. But - imposing unhealthy and unnecessary elevated blood glucose levels on individuals who have never had a hypoglycemic incident and who are not taking medication that increases their likelihood above that of a person without diabetes is inappropriate, and discourages disclosure (or encourages unhealthy practices) by those of us with diabetes who are actually the least likely to have any hypoglycemic incidents.

{I have checked with DAN, and have been assured that the guidelines are not intended to be applied rigidly to people with diabetes well-controlled by diet and metformin who know how exercise impacts their blood glucose levels. My personal challenge, as a rule-follower, is that there is no formal (or even informal) exception to the guidelines for people in my circumstances.}

I will disagree a bit, though, about hyperglycemic incidents not being an issue. Even at 130, which is very very mildly hyperglycemic, my mental acuity suffers. The cutoff guidelines for a hyperglycemic hold on diving are set at 300. In my opinion (based on both personal experience - and experience with my spouse), that is well beyond the point at which elevated blood sugar impairs mental acuity and short term memory. It is not nearly as dramatic as a hypoglycemic incident - but it is at least the equivalent of having a beer before hitting the water.