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Condition: Diabetes mellitus (DM) is a disorder of the endocrine
system, manifested by one of two things: an insufficient production of insulin
or the resistance of the body's cells to the actions of insulin despite normal
or high levels. People with DM often have excessively high blood glucose (BG),
called hyperglycemia, or an excessively low BG, better known as hypoglycemia.
Diabetes mellitus itself has two major forms: Insulin-requiring diabetes
(IDDM, Type 1),* for which insulin must be given by injection to control blood
sugar levels; and non-insulin-dependent diabetes (NIDDM, Type 2), which may be
controlled by diet or by oral medications (oral hypoglycemic medications).
The main risk to the diver is the occurrence of hypoglycemia, that can
manifest itself as confusion, sweating, rapid heartbeat, unconsciousness and
even death. High blood sugar levels, or hyperglycemia, may also cause
unconsciousness, although this usually develops much more slowly than
hypoglycemia. Impaired consciousness underwater leads to almost certain death.
Although hypoglycemia occurs most commonly in Type 1, it can also occur in
individuals taking oral hypoglycemic medications. Hypoglycemia experienced
during a deep dive may be wrongly perceived as nitrogen narcosis.
Although hypo- or hyperglycemia can occur daily, other problems can develop
over the long term, in persons with diabetes. These maladies include:
retinopathy (alterations in visual acuity); disorders of the kidneys; coronary
artery disease; and changes in the nervous system, including abnormal nervous
conduction and atherosclerosis, that can cause poor circulation in the limbs.
Fitness and Diving: Divers with diabetes are at risk of sudden loss of
consciousness. This carries the ultimate risk of drowning and implies additional
risks for their dive buddies. Individuals with diabetes, however well the
diabetes is controlled, should not be deemed as fit to dive without restriction.
Those who meet certain criteria can dive provided they dive in accordance with
detailed, specific procedures (See Diabetes & Diving: Current practices
demonstrate that many with diabetes do take the plunge; By Guy de Lisle Dear,
M.B., FRCA, Alert Diver, January / February 1997). Divers with diabetes should
be examined periodically for complications of their disorder that may disqualify
them on the grounds of additional risk.
Medication Used in Treatment: Sulphonylureas (drugs that posses
hypoglycemic action) such as glipizide, glibenclamide, chlorpropamide and
tolbutamide may interact with numerous other drugs used to lower BG.
- Biguanides (metformin) may cause self-limited (gastrointestinal side effects
and may cause problems* in individuals with renal, liver or heart diseases.
- Acarbose (an alpha-glucosidase inhibitor) is also used in conjunction with
other agents when the more simple sulphonureas do not work adequately to control
blood glucose. Insulin acts to lower BG. In general, diving with diabetes is not
recommended. An additional consideration: insulin requirements may change
substantially with demands of exercise and diving.
There is a small risk of lactic acidosis which is markedly increased by any
condition that reduces metformin clearance (acute or chronic renal impairment)
or compromises oxygen delivery and predisposes to tissue hypoxia (acute or
chronic respiratory or cardiovascular insufficiency) in persons with renal,
liver or heart diseases.
Additional Information:
- Diabetes.com -- www.diabetes.com/
- The National Institute of Diabetes and Digestive and Kidney Diseases or
(NIDDK) -- www.niddk.nih.gov/
- Diabetes & Diving: Current practices demonstrate that many with diabetes
do take the plunge -- How safe is it? by Guy de Lisle Dear, M.B., FRCA, DAN
Assistant Medical Director, Alert Diver, January/February 1997.
Note: The acronym IDDM actually stands for the older term insulin-dependent
diabetes mellitus, although the newer term for this condition is termed
insulin-requiring diabetes mellitus, and is still represented as IDDM. The
diabetes community currently is in transition between nomenclatures.
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