Insulin pump and boat diving

[The Iceni]

DocVikingo once bubbled...
And the support for this assertion is?

Hi DocVikingo,

In my humble opinion if an insulin dependent diabetic needs a continuously adjustable supply of insulin, however it is controlled, he must be, almost by definition, a brittle diabetic.

This is a matter of risk reduction.

As you know apart from fasting any patient with IDDM can only reduce his blood sugar in two ways.

1. Exercise
   
2. Taking insulin
   [/list=1] Given that the metabolic rate during a normal dive is in excess of 4 METs the energy needed will be derived initially from blood glucose and subsequently from glycogen stores. I very much doubt there will be much gluconeogenesis/lipolysis unless blood sugars are dangerously high prior to the dive (producing ketoacidosis).
   
   Thus the only effective energy source will be the rapid-access carbohydrate stores in the body. As you know a patient with IDDM is unable to charge these stores from the blood glucose in the absence of insulin. In excess insulin, dangerously low blood sugars result from an excessive transfer of blood glucose INTO the cells that normally hold the glycogen stores - muscle and liver. Too high an insulin dose results therefore in dangerously low blood sugars.
   
   I do not believe you would dispute that "The main additional risk of diving with diabetes is low blood sugar (a "hypo") with resulting unexpected loss of consciousness. " In diabetes the aim is to control blood glucose to keep it above a level so low as to cause a hypo and below the level at which the long-term complications are more likely to develop, and these are generally thought to be mainly due to the direct local effects of excess glucose on cell membranes, particularly the capillaries which become leaky, forming fibrous plaques in the vascular walls.
   
   If control is good, and in my opinion no diabetic should dive if it is not, it would seem logical that any contribution to the long term damage caused by relatively high levels of blood glucose that could develop during a dive in which there is relatively too little insulin pales in comparison with the disastrous effects that could ensue should a diver have relatively too much insulin on board. My incident illustrates what can happen, and worse, to any diver who simply loses consciousness!
   
   As I am sure you know, even the rapid acting insulins have a relatively prolonged biological half-life, and without a large carbohydrate meal to replenish the body's glucose stores during its biologically active phase, the effect of insulin is to cause the absorbtion of blood glucose mainly into muscle and liver cells for glycogenesis, over several hours, resulting in a gradual reduction in blood glucose levels.
   
   When this glucose is also being used for aerobic work it is axiomatic that blood levels will be even more rapidly decreased.
   
   Thus is seems foolhardy to do anything that could further reduce blood glucose levels during a dive. Therefore to carry a device that continues to add insulin during a dive is to my mind unwise. In addition this is yet another item of equipment to fail and a massive bolus of insulin administered during a dive would be catastrophic, to say nothing about the risks of infection.
   
   I will restate

   . . .preventing a hypo and being able to treat it properly are the most important considerations. Thus . . 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.

   Most diabetics ought to know more about their disease than their doctors and this is particularly the case for diabetic divers.
   
   Brick Smith, describes his personal experiences from the perspective of someone who belives he knows his illness well and what works for him but I would not recommend this for every diabetic diver.
   
   That is my professional opinion.
   
   Best wishes. :doctor:

 

[BILLB]

Thanks to Dr. Paul Thomas, I now have a understandung of this disease from a diver's point of view with hard facts to support it.

I have nothing but sympathy for divers who want to continue to dive with diabetes. As with any diving activities, the at risk diver also place other divers at risk and this must be accounted for.

As an instructor, I have chosen not to enlist insulin dependant diabetics as students. I am not medically prepared to deal with many of the complications and the liabilities are simply overwhelming.

 

[JT2]

Great post Dr. Paul. While I disagree with you on a few things you stated in your post, I do however think it was a well written and informative post. While I realize that I am not a doctor, nor do I have any professional medical training outside of first aid, I am an insulin dependent Diabetic and have been for over 17 years now and I have been diving for a great many of those years so I believe I am somewhat qualified to debate this topic.

Dr Paul Thomas once bubbled...

On no account should an insulin pump be used underwater as this will almost certainly reduce blood glucose to dangerous levels.

While I agree that an insulin pump should never be used while scuba diving my reasons for this statement differ from your above quote in that I feel there are too many things that could go wrong with the equipment which would cause serious problems for the user and the pump itself, however, saying that using an insulin pump underwater will almost certainly reduce blood glucose to dangerous levels is somewhat of a blanket, and misleading statement. If there was a pump made that was designed for underwater-at pressure use, and all of the other equipment and infusion set problems were solved and failproof, there is no reason why someone could not dive while wearing and using an insulin pump. I will follow that up by saying that the pump user would most definitely have to modify their basal rate and programed boluses just as they would if they were going to workout, jog, or do any other physical activity, but other than that it would be no different.
I would also like to back up some of the things you said such as always make sure and tell everyone you dive with what your situation is and never hide the fact that you are a diabetic as this could get you or them hurt. I would also strongly suggest that the diabetic diver have a regular dive buddy/buddies that they dive with since I do not feel that a simple briefing before the dive is enough information for someone to know what to do or what to look for if they know nothing about diabetes.

On a side note I have several years of very interesting and informative dive logs and glucose testing while diving that I have done with the help of many others who have helped me research diving with diabetes, and I have just recently sent them to DAN so that they may study the results in the on going research they are doing on diving with diabetes. I would be willing to share this information with any of the Doctors here on the board who are interested in seeing them and might want to study them as well.

PS. To anyone reading this, I Greatly respect the abilities and knowledge of Dr Paul Thomas and all of the other doctors on the scuba board and is not my intent to be argumentitive, as they have FAR Greater knowledge than I do and they are always looking out for everyones safety here on the board.

 

[DocVikingo]

To refocus, my last inquiry specifically addressed the assertion, "On no account should an insulin pump be used underwater as this will almost certainly reduce blood glucose to dangerous levels."

I am agreement with JT2 that this is, "... somewhat of a blanket, and misleading statement."

In my view, there is no necessary expectation that use of an insulin pump underwater would reduce blood glucose to worrisome levels. It would simply be a matter of titrating the delivery of insulin to a level appropriate to the anticipated degree of exertion. Physically active diabetics using insulin pumps make such adjustments on a routine basis, and with modern units extremely quickly & easily, I might add.

I submit that the raison d'être of these devices is to allow a person with diabetes to effectively deal with changing activity levels, varied schedules, changes in diet, and the like. It is my understanding that they do so quite well.

Concerns regarding mechanical failure & infection are, of course, separate matters, although requiring serious consideration.

As long as we're engaged, let's examine several more of your assertions:

1. "..if an insulin dependent diabetic needs a continuously adjustable supply of insulin, however it is controlled, he must be, almost by definition, a brittle diabetic."

This is not my perspective, nor do I suspect that of many diabetologists. Leaving aside the marvelous flexibility afforded by pump technology, modern science & medical thought are that very tight control of diabetes is in the best interests of all diabetics, not just "brittle" ones. Pumps go a long way in the consistent & harmonious fine-tuning of blood glucose levels, and avoid the often notorious unpredictability/variability of the long-acting insulin analogues as typically used in the interminable injection regimen.

2. "As I am sure you know, even the rapid acting insulins have a relatively prolonged biological half-life, ...."

The use of such insulin analogues is not a simple matter. Nonetheless, the reported elimination half-lives of some very rapidly acting insulins appropriate for use in pumps are on the order of 45-80 minutes, with durations of action of no more than 3-4 hours, depending on a number of factors.

3. "I do not believe you would dispute that 'The main additional risk of diving with diabetes is low blood sugar (a "hypo") with resulting unexpected loss of consciousness. '"

My published article on diving & diabetes, which I have posted multiple times on this forum, most recently just 2 months ago in a thread in which your yourself participated---> http://www.scubaboard.com/showthread.php?s=&threadid=20876&highlight=diabetes+rodales, indicates that I would not dispute this. In fact, paragraph #3 of that piece reads: "For the diabetic diver, the most worrisome immediate risk is blood glucose falling to a level where hypoglycemia, or low blood sugar, is precipitated. This can result from events such as too much insulin, alcohol or exercise, or too little or improper eating. An episode can cause weakness, tremor, sweatiness or chilling, irritability, alterations or loss of consciousness, and convulsions."

Best regards.

DocVikingo

 

[ppo2_diver]

I agree with DocVikingo. I believe Dr. Thomas's definition of "brittle" diabetics is wrong. I have the same blood sugars and HA1C now than when I was on daily injections. The pump only freed me from having been tied to a daily regimine of when to wake up, when to eat, and how much to eat. The only benefit the pump gives me is that now I don't have those tight restrictions. In other words, it is more convienent for me to be on the pump. In the two years I've been on the pump, I have had ZERO low blood sugar reactions. This has allowed me to become a diver and enjoy other activities. Also, all insulin dependant diabetics need a continuouse supply of insulin. So according to Dr. Thomas all Type 1 diabetics are "brittle" diabetics?

I also disagree with instructors who will not teach diving to people with diabetes. The biggest rule I learned in my OW course was to dive within your means. I know my limitations as a diabetic and a diver. I have over 300 dives with 100 of those in overhead environments, and I have never had a problem with my disease. I dive within my means and I am overly cautious on the surface of what my blood sugars are. I am also currently a DiveMaster in training. It is my opinion that scuba diving professionals (instructors & DMs) need to be aware of these conditions to give the best, and safest, diving instructions possible to anyone who wants to participate in our great sport. They should just not know about diabetes, but allergies and asthma too. I am currently writting a paper on this very topic and I will be try to push it at Our Underwater World this month and to DAN and other training agencies once I have it completed. I'd be interested in hearing other opinions on this. JT2, I'm also interested in your research.


Duane

 

[The Iceni]

DocVikingo once bubbled...
Physically active diabetics using insulin pumps make such adjustments on a routine basis, and with modern units extremely quickly & easily, I might add.

I submit that the raison d'être of these devices is to allow a person with diabetes to effectively deal with changing activity levels, varied schedules, changes in diet, and the like. It is my understanding that they do so quite well.

Hi DocVikingo & JT2,

This is a very interesting discussion, which I suspect has left the majority of readers totaly confused. Please do not get me wrong I am the last person to refuse to dive with a diabetic but I do think it is important to minimise risks and legal liability.

I entirely accept much of what you say, and what JT2 posted. My worry is that this is a public forum and the average British diver tends to be rather too cavalier about all things medical and denial is a common feature, particularly in the younger newly diagnosed insulin dependent diabetics. Puberty is trauma enough.

Concerns regarding mechanical failure & infection are, of course, separate matters, although requiring serious consideration. . .

1. "..if an insulin dependent diabetic needs a continuously adjustable supply of insulin, however it is controlled, he must be, almost by definition, a brittle diabetic."

This is not my perspective, . . . Pumps go a long way in the consistent & harmonious fine-tuning of blood glucose levels, and avoid the often notorious unpredictability/variability of the long-acting insulin analogues typically relied upon in the interminable injection regimen.

Perhaps I overstated the case, but this is probably because our NHS will not yet provide insulin pumps to the average diabetic. They are wonderful devices but sadly are reserved for brittle cases.

2. "As I am sure you know, even the rapid acting insulins have a relatively prolonged biological half-life, ...."

The use of such insulin analogues is not a simple matter. Nonetheless, the reported elimination half-lives of some very rapidly acting insulins appropriate for use in pumps are on the order of 45-80 minutes, with durations of action of no more than 3-4 hours, depending on a number of factors.

Now we get to the crux of the matter. It seems to me that the risks (of using a pump duiring a dive) outweigh the benefits at this time. JT2 clearly knows his body and his illness well and, like Brick Smith, is well placed to make an informed decision. I suspect this is not always the case. By far the most important feature is for the diabetic diver to convince himself, the dive marshal and his buddy that he has done all in his pwer to prevent a hypo when underwater and a series pre-dive tests would appear mandatory. In his article you referenced, Brick Smith admitted to suffering a hypo at the end of a dive. It is just as well he was on the surface.

Thank you for confirming my understanding of the bioavailability of insulin. The average duration of a scuba dive is unlikely, greatly to exceed an hour. It therefore seems logical for even a diabetic who uses a pump to go without adding more insulin during the actual dive - with its attendant risks - since even the rapid acting insulins already in the body will still be biologically active long after the dive has finished. It would be a very simple matter for that diver to give himself a bolus dose of the insulin missed on his dive (via his pump) immediately on de-kitting in order to maintain overall control on that particular day.

I still feel the considerable short term risks greatly outweigh any longer term benefits of using the pump underwater but I am no diabetologist and thankfully I am not an insulin dependent diabetic diver.

Bill B has highlighted some of the problems diabetics face.

One factor that has been overlooked is how the courts or life insurance companies might react if a diver suffered a hypo during a dive in which he was using a pump underwater. Glycaemic control is important but I wonder if this has been fully thought through. A dive is not at all the same as a cross-country run or a gym workout.

I still feel extreme caution is advised, and for the average diabetic diver I believe my approach is a sensible one.

Kind regards,

 

[DocVikingo]

To refocus on the particular assertions that you initially adduced, and with which I took issue:

1. "On no account should an insulin pump be used underwater as this will almost certainly reduce blood glucose to dangerous levels."

You now state that you entirely accept much of what I have said as regards the accuracy of this assertion, which is that there is no necessary expectation that use of an insulin pump underwater would reduce blood glucose to worrisome levels.

Good, as I feel that the position is cogent, as seemingly does JT2.
You go on to say that your actual worry here is that since "... this is a public forum and the average British diver tends to be rather too cavalier about all things medical and denial is a common feature, particularly in the younger newly diagnosed insulin dependent diabetics."

This strikes me as a rather different concern than the originally cited assertion, although I suspect that it has merit.

2. "..if an insulin dependent diabetic needs a continuously adjustable supply of insulin, however it is controlled, he must be, almost by definition, a brittle diabetic."

I agree that perhaps you overstated the case, but in any event would argue that the policies of your NHS regarding paying for insulin pumps really should not be a consideration in the definition of a brittle diabetic. As you know, such decisions are heavily influenced by non-medical factors.

3. "As I am sure you know, even the rapid acting insulins have a relatively prolonged biological half-life, ...."

You have responded with, "The average duration of a scuba dive is unlikely, greatly to exceed an hour. It therefore seems logical for even a diabetic who uses a pump to go without adding more insulin during the actual dive - with its attendant risks - since even the rapid acting insulins already in the body will still be biologically active long after the dive has finished. It would be a very simple matter for that diver to give himself a bolus dose of the insulin missed on his dive (via his pump) immediately on de-kitting in order to maintain overall control on that particular day."

I do not disagree with this position. However, it appears to me to be somewhat different than the argument you put forth in original support of the assertion, which was, "... without a large carbohydrate meal to replenish the body's glucose stores during its biologically active phase, the effect of insulin is to cause the absorbtion of blood glucose mainly into muscle and liver cells for glycogenesis, over several hours, resulting in a gradual reduction in blood glucose levels."

All of this is not to minimize your concern with and the seriousness of decisions on whether or not to dive with diabetes.

However, your comment that the discussion thus far may have left the majority of readers confused well may be true. It is because of this possibility that I strongly urge it be clearly, tightly & consistently reasoned, and arguments compellingly bolstered and carried to their logical end points. Hopefully, others will do a better job of this than I.

Best regards.

DocVikingo

 

[The Iceni]

I did find a thread where someone wore his MiniMed pump to a depth of 20 feet and the thing broke open.

'spensive!

 

[JT2]

BILLB once bubbled...
As an instructor, I have chosen not to enlist insulin dependant diabetics as students. I am not medically prepared to deal with many of the complications

Good for you BILLP, I think it is a very responsible decision that you have made based on your abilities. I am as everyone here probably knows by now a diabetic diver and have been for many years, I do not however feel that instructors should accept diabetic students if they are not very familiar with the disease and how it is treated, and I also do not think that it is reasonable to expect all instructors to be able to safely teach diabetics. The YMCA has a program for diabetic divers and I suspect at least one or two others will follow their lead.

Dr Paul Thomas once bubbled...
In my humble opinion if an insulin dependent diabetic needs a continuously adjustable supply of insulin, however it is controlled, he must be, almost by definition, a brittle diabetic.

In a healthy non-diabetic body does the pancreas not deliver a contiuously adjusted supply of insulin as needed??? Isn't this the idea behind the insulin pump?? I can almost guarantee you that almost ANY insulin dependent, not just "brittle" diabetics could more closely control their glucose levels with an insulin pump than with injections. There are reasons that an insulin dependent diabetic may not want to wear a pump, such as cost and inconvenience just to name a couple. I for one have worn an insulin pump and found it to be too cumbersome and always in the way because of my very active lifestyle(I was always bumping it into things or ripping out the infusion set). I have taken a different approach to diabetes treatment than most people in that I take my insulin on a sliding scale and use primarily short acting insulin(TypeR). I basically check my glucose levels 6-10 times a day and take insulin according to what my glucose levels are, and I have found I can maintain very tight control that way as well as have a lot more flexibility when I eat my meals and do my exercising. Flexibility is something that I must have since I am a salesman and I never know how many hours a day I may have to work or when I am going to get to eat.

jhnsndn once bubbled...
I am currently writting a paper on this very topic and I will be try to push it at Our Underwater World this month and to DAN and other training agencies once I have it completed. I'd be interested in hearing other opinions on this. JT2, I'm also interested in your research.

I would be happy to share some of my research with you for this paper, but the last thing I want is someone trying to mimick some of my dive profiles or some of the things I have done in my research on this topic. All diabetics are different and in my opinion must have excellent control of their glucose levels in and be very knowledgable of the disease and theirselves before ever attempting to signing up for a dive class. If you would like to hear more about my research jhnsndn feel free to PM me.

 

[The Iceni]

JT2 once bubbled...
In a healthy non-diabetic body does the pancreas not deliver a contiuously adjusted supply of insulin as needed??? Isn't this the idea behind the insulin pump?? I can almost guarantee you that almost ANY insulin dependent, not just "brittle" diabetics could more closely control their glucose levels with an insulin pump than with injections.

I couldn't agree more JT2!

As is so often the case we seem to have wandered well away from answering the quesion the original poster made and have got ourselves bogged down into argueing the toss over minutiae and confusing the issue to no good purpose.

I have no doubt that before long we will have automaticaly controlled pumps that will calculate the body's insulin needs on a minute to minute basis but we are not there yet. My hope for the future is the promising possibility of islet cell transplants. This has the considerable benefit of "curing" the patient and freeing them from dependence on a machine to keep them alive and healthy in much the same way that kidney transplants free patient from dialysis.

May I quote from my original post, just to set the record straight?

. . . 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.

You also posted.

There are reasons that an insulin dependent diabetic may not want to wear a pump, such as cost and inconvenience just to name a couple. I for one have worn an insulin pump and found it to be too cumbersome and always in the way because of my very active lifestyle (I was always bumping it into things or ripping out the infusion set).

Isn't scuba diving pretty active?

My concerns are not confined to endocrinology alone. I have therefore edited my original post to highlight this.